黄建峰
Jianfeng Huang
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收稿日期: 2017-09-16
接受日期: 2018-03-27
网络出版日期: 2018-03-20
版权声明: 2018 《生物多样性》编辑部 版权所有.《生物多样性》编辑部
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摘要
榕-传粉榕小蜂系统是研究动植物专性互惠共生关系的经典体系。早期形态学研究认为它们之间遵循一对一原则, 即1种榕树只有1种榕小蜂为其传粉, 而1种传粉榕小蜂也只能在1种榕树上繁殖后代。然而随着研究的深入, 报道了越来越多非一对一共生关系的案例, 尤其是隐存种的发现, 打破了一对一原则在榕-传粉榕小蜂系统中的普适性。非一对一共生关系包括多种传粉者共现于1种宿主榕树和多种榕树共享1种传粉者两种情况, 有各自不同的发生机制和规律。本文从形态学描述阶段、多学科综合证据阶段和传粉榕小蜂隐存种的发现3个阶段综述了榕-传粉榕小蜂非一对一共生关系的研究进展, 并对其所引发的科学问题进行了探讨。多种传粉者共现于1种宿主榕树的情况, 使得榕小蜂的种间杂交成为可能; 而多种榕树共享1种传粉者, 为宿主榕树的种间杂交提供了机会。然而, 杂交事件的检出率却很低, 暗示存在明显的生殖隔离。另外, 传粉者共现和共享传粉者两种情况在不同性系统榕树上的发生率和发生机制存在明显差异, 暗示不同性系统榕树的宿主专一性不同。大量小蜂隐存种的发现, 引发了对其成种机制、共现机制的研究, 以及对小蜂生物多样性的重新评估, 并给人工控制实验的开展带来了新的问题。每个榕-传粉榕小蜂组合都具有其独特的协同进化历史, 为研究动植物间的协同进化机制和规律提供了丰富素材。对榕-传粉榕小蜂专性互惠共生关系的形成、维持和打破机制开展综合研究, 才能充分认识该系统, 也有助于认识动植物间的协同进化过程和规律。
关键词：
Abstract
The fig-fig-pollinating wasp symbiosis provides a model system for investigating the mutualistic interaction between plants and animals. A simple one-to-one rule was proposed to describe the highly specialized reciprocal relationships between figs and their species-specific pollinating fig wasps based on the initial studies: each fig tree species is obligatorily pollinated by one fig wasp species, and each wasp species can only reproduce in one fig species. With the deepening of research, however, increasing cases of breakdown in species-specificity have been reported, especially the reveal of cryptic pollinating fig wasp species progressively weaken the universality of one-to-one rule in fig-fig-pollinating wasp symbiosis. The documented cases of breakdown in the one-to-one rule were divided into two types, including copollinator and pollinator sharing, which have their own different mechanisms. Pollinator sharing is pollination of different species of Ficus by the same pollinator, while copollinator is the co-occurrence of more than one species of pollinators in one host fig. Here, the research progress on the breakdown of one-to-one rule is presented in three stages, i.e. morphological description, multidisciplinary evidence and discovery of cryptic pollinating wasp species. Some future challenges and research prospects resulted from the breakdown of one-to-one rule are outlined. Copollinators may lead to the interspecific hybridization between pollinator species, while pollinator sharing may result in the hybridization of host figs. Nonetheless, the hybridization in fig-fig-pollinating wasp symbiosis is very rare and suggests a strong level of reproductive isolation. Furthermore, the incidence and pattern of pollinator sharing and copollinator are differentiated in dioecious and monoecious figs, which suggests a differentiated host-specificity. The identification of cryptic species triggers the research of its speciation and co-occurrence, as well as the reassessment of pollinator biodiversity. Failing to recognize cryptic species also will limits the effectiveness of the controlled experiment in fig-fig-pollinating wasp symbosis. Each pair of fig and pollinating wasp possesses its distinctive coevolutionary history, and there are more than 750 pairs across the globe, which provide rich materials to explore the coevolutionary process and mechanism between plants and animals. The integrated study of formation, maintenance and breakdown mechanisms of the host-specificity will contribute to the understanding of fig-fig-pollinating wasp mutualism, and the coevolutionary process and mechanism between plants and animals.
Keywords：
协同进化塑造着种间关系, 影响着生态系统的结构和功能及其动态。榕树及其传粉榕小蜂构成的互惠共生系统(以下简称榕-传粉榕小蜂系统)早在7,500万年前就已建立, 是动植物间最紧密的协同进化关系之一(Cruaud et al, 2012)。榕树是榕属(Ficus)植物的总称, 隶属于桑科, 全球约750种(Berg, 1989)。榕树有乔木、灌木、攀援藤本等丰富的生活型, 占据雨林中的乔木层、灌木层、藤本层(Harrison, 2005), 一些榕树还具有气根、板根、绞杀、独木成林、老茎生花等独特现象。榕树为多种动物提供了食物和栖息地, 被公认为热带雨林的关键类群(许再富, 1994; Shanahan et al, 2001)。
所有的榕树均具隐头花序, 隐头花序也被称为榕果, 其顶部有一个由苞片组成的苞片口, 是榕果与外界交流的唯一通道(Janzen, 1979)。这种特殊结构使得榕树需要依赖专性的传粉榕小蜂才能完成有性生殖; 同时隐头花序也为传粉榕小蜂提供产卵、繁衍后代的场所。从高达数十米的大乔木到低矮的匍匐藤本, 榕树都依赖大小只有1-3 mm、成虫期只有1-2天的专性传粉榕小蜂传粉, 两者在形态、生理、生态、行为等方面都达到了高度适应。这种相互依赖、不可或缺的关系被Wiebes (1963)用“一对一”原则(one-to-one rule)来描述。该原则被认为在榕-传粉榕小蜂系统中具有普适性, 即1种榕树只有1种传粉榕小蜂为其传粉, 而1种传粉榕小蜂也只能在1种榕树上繁殖后代。这种高度专性互惠共生关系的形成和维持成为一个自然之谜, 吸引了众多国内外学者去探索。然而, 对这种一对一关系的质疑一直存在。随着技术和研究方法的革新, 发现了越来越多打破一对一原则的案例, 包括多种传粉者共现于1种宿主榕树和多种榕树共享1种传粉者两种情况。正如其他新观点、新理论的出现一样, 榕-传粉榕小蜂系统非一对一共生关系的观点也经历了早期的反对和质疑、实验的反复验证, 再到最后被接受三个阶段。
早在1886年, Müller就记录了多种榕树共享传粉榕小蜂Blastophaga brasiliensis的情况(Müller, 1886)。Grandi (1916)报道了小蜂Eupristina saundersi为印度境内菩提树(F. religiosa)传粉的情况, 但同时也发现菩提树还存在另一种传粉小蜂, 即分布于马来西亚(Mayr, 1885)、印度、斯里兰卡(Grandi, 1922; Joseph, 1953; Johri & Konar, 1955)和以色列(Wiebes, 1963)的Platyscapa quadraticeps。后来的学者认为Grandi (1916)的报道在宿主鉴定方面存在错误, 因为E. saundersi的雄虫发现于F. retusa var. nitida (Wiebes, 1963; Rasplus, 1996)而非菩提树。Grandi (1927)还报道了菲律宾群岛分布的F. ulmifolia和F. heterophylla共享传粉者Blastophaga browni的情况, 但进一步研究发现菲律宾群岛并没有F. heterophylla分布, 最初被认为是F. heterophylla的标本均属于F. ulmifolia (Wiebes, 1963)。基于形态特征描述榕-传粉榕小蜂非一对一共生关系的报道还很多, Wiebes (1963)总结了打破一对一原则的案例, 认为这些案例基本上都源于宿主或传粉榕小蜂种类鉴定错误, 并不可信。
一年之后, Wiebes (1964)报道了Ceratosolen arabicus和C. galili两种小蜂共现于非洲榕树植物F. sycomorus的情况。其中C. arabicus是有效传粉者, 为F. sycomorus主动传粉; 而C. galili有发达的花粉筐, 但无花粉刷, 缺乏主动传粉行为, 是一种只寄生不传粉的欺骗者(Galil & Eisikowitch, 1968, 1969)。C. galili能独自占据F. sycomorus一半以上的榕果, C. arabicus独占榕果的比率相对较低, 而两者共现的榕果约占13%。但C. galili繁殖的后代数量比C. arabicus少, 而且个体较小, 这可能是C. galili进化为欺骗者所付出的代价(Compton et al, 1991)。基于Cytb基因开展的研究显示宿主转移(host shift)是C. galili进化为欺骗者的机制(Kerdelhué et al, 1999)。进一步研究发现, 虽然传粉者C. arabicus和欺骗者C. galili分布区重叠, 但两者在生理和行为上有显著差异: C. arabicus成虫期寿命较长, 耐高温、干旱和饥饿的能力强, 并在白天飞行寻找接受期榕果; 而C. galili抗逆能力差, 在夜晚飞行活动, 恶劣的气候和环境条件对这类欺骗者的影响比对传粉者更大(Warren et al, 2010)。这种欺骗者类似于非传粉的寄生榕小蜂, 与传粉榕小蜂在功能、生理、生态等多方面存在分化。类似的情况也存在于高榕(F. altissima) (Peng et al, 2008, 2010)和小叶榕(F. microcarpa) (Martinson et al, 2014)。Boucek等(1981)认为Ellsabethiella stuckenbergi、Alfonsiella brongersmai和A. longiscapa共现于F. thonningii的情况可能也是类似的机制。
Ramírez (1970a)报道了小蜂Pegoscapus mariae存在于F. tuerckheimii和F. jimenezi两种榕树的情况。但F. jimenezi的成熟榕果中只发现了其专性传粉者P. jimenezi的后代, 未发现P. mariae小蜂后代, 说明P. mariae虽然能够进入F. jimenezi榕果, 但不能成功繁殖。另外, Ramírez (1970b)在委内瑞拉境内一株榕树F. turbinata上发现, 5%的榕果被其他非专性传粉榕小蜂拜访, 并能成功繁殖小蜂后代、产生种子, 但种子不能萌发, 而其专性传粉者拜访的榕果所产生的种子具有100%的萌发率。上述两例打破一对一原则的现象, 只是由于传粉者偶然的误访, 并不能成功繁殖小蜂后代或产生可育的宿主种子, 并未真正打破一对一原则。
由于早期研究基于形态和野外观察, 有时还存在鉴定错误(Grandi, 1916, 1927); 或因凭证标本丢失而不能核实(Wiebes, 1963); 或因自然界偶然发生传粉榕小蜂误访, 但不能产生小蜂后代和可育种子(Wiebes, 1970a, b); 或因共现的传粉榕小蜂中只有1种为宿主传粉, 而其他种类为不传粉的寄生者或欺骗者(Galil & Eisikowitch, 1968, 1969)等, 所以打破一对一原则的观点并未得到普遍认可。
首例被学者们广泛接受的传粉者打破一对一原则的实例报道于1985年。分布于非洲中西部加蓬地区的榕树F. ottoniifolia有2种传粉榕小蜂, 即Courtella camerunensis和C. gabonensis。它们都具花粉筐, 能为宿主主动传粉, 并产生可育种子和小蜂后代; 两者同域分布, 甚至能生存于同一榕果(Michaloud et al, 1985)。但它们的生境偏好不同: C. camerunensis偏爱郁闭的雨林生境, 此生境中57%的F. ottoniifolia榕果被其独占, 只有20%的榕果被C. gabonensis独占; 而C. gabonensis偏爱开阔生境(例如农田或村落边), 其中68%的榕果被其独占, 只有6%的榕果被C. camerunensis独占; 在过渡的森林边缘地带, 榕果中2种小蜂的数量呈现此消彼长的格局; 但从雨林向开阔生境过渡的过程中, 榕果中C. camerunensis小蜂数量显著减少, 而C. gabonensis数量缓慢增加(Michaloud et al, 1985, 1996)。但无论在哪种生境中, 同一株榕树上几乎都存在2种小蜂, 并且23-26%的榕果有2种小蜂(Michaloud et al, 1996)。Michaloud等(1985, 1996)还报道了Ceratosolen capensis、C. flabellatus和C. silvestrianus共现于非洲榕树F. sur的情况。3种小蜂均能够为F. sur主动传粉, 并产生种子和小蜂后代(Kerdelhué et al, 1997)。其中, C. capensis为非洲大陆南部和东北部分布的F. sur传粉, C. flabellatus和C. silvestrianus为非洲西至中东部的F. sur传粉。在非洲西部, C. flabellatus和C. silvestrianus可存在于同株榕树, 但几乎不共现于同一榕果。从更大范围来看, 非洲西部喀麦隆境内海拔较高的Buea、Bamenda高地以及Monts Mandara地区的F. sur只有C. silvestrianus为其传粉(Michaloud et al, 1996)。生境偏好和异域分布能够有效避免种间竞争, 这可能是上述两个案例发生传粉者共现的重要机制。基于此, Michaloud等(1996)提出了异域成种(allopatric speciation)和宿主转移2个途径或假说来解释传粉者共现现象。
随着3部关于榕-传粉榕小蜂系统专著的发表(Wiebes & Compton, 1990; Berg & Wiebes, 1992; Wiebes, 1994), 越来越多打破一对一原则的案例被报道。例如, Berg和Wiebes (1992)发现在非洲的105种榕树中, 24种存在非一对一共生关系; Wiebes (1994)在亚洲和澳洲分布的175种榕树中, 发现11种打破一对一原则的案例。Rasplus (1996)进一步指出, 在已知的榕-传粉榕小蜂组合中, 约有13%的组合不符合一对一原则, 其中非洲17%的榕树种类具有至少2种传粉榕小蜂, 约15%的小蜂物种存在于2种或2种以上的宿主榕树; 这个比例在澳大拉西亚地区分别为13%和7%。Cook和Segar (2010)总结了142种雌雄同株榕树的研究, 发现其中45种存在多种传粉者, 比例高达32%。
相对而言, 共享传粉者的案例比较少见(Rasplus, 1996)。木瓜榕(F. auriculata)和苹果榕(F. oligodon)共享传粉榕小蜂Ceratosolen emarginatus的情况很早就被提及(Wiebes, 1963), 它们和海南榕(F. hainanensis)以及北碚榕(F. beipeiensis)均属于木瓜榕复合体(F. auriculata complex), 不少学者对它们的分类地位存在疑问(Corner, 1965; Berg & Corner, 2005), 最新的分子证据建议把它们合并为一个种(Zhang et al, 未发表数据)。Rasplus (1996)报道了小蜂Ellsabethiella socotrensis为索科特拉岛、埃塞俄比亚和沙特阿拉伯境内的F. vasta, 以及肯尼亚和赞比亚境内的F. wakefieldii传粉的情况; 后来发现该种小蜂还为非洲南部的F. natalensis传粉(Cornille et al, 2011)。Cornille等(2011)还发现F. natalensis与F. burkei共享小蜂E. stuckenbergi, 并发现这2种榕树的接受期榕果能够释放高度相似的化学挥发物, 这被认为是吸引小蜂发生宿主转移从而为2种宿主传粉的重要机制。异形花榕(F. heterostyla)和肉托榕(F. squamosa)为2种分布于亚洲热带大陆的雌雄异株榕树, 刘桂香(2013)①(①刘桂香 (2013) 榕树与传粉榕小蜂非一对一关系演化的生态学机制. 硕士学位论文, 中国科学院大学, 北京)和Liu等(2015)发现分布于我国西双版纳地区的异形花榕和肉托榕共享1种未描述的传粉榕小蜂新种Ceratosolen sp.。该种小蜂能够为2种榕树主动传粉, 并成功繁殖小蜂后代。2种榕树在西双版纳地区虽同域分布, 但偏爱生境不同。肉托榕为小灌木, 偏爱生长于水流两岸或裸露于水面的岩石缝中, 雨季洪水期常被浸泡于流水中, 水流传播被认为是其种子的主要传播方式(Pothasin et al, 2016); 异形花榕为小乔木, 偏爱生长于次生林边缘和道路两旁。物候调查发现, 肉托榕结果期集中在干季, 雌雄株均在3月达到结果高峰; 分布于河流边的肉托榕在雨季的7-9月会淹没于洪水中, 不结果。异形花榕种群全年都有树结果, 7月份达到结果高峰, 2-3月结果量最少。这种互补的结果物候被认为是传粉榕小蜂在同域分布的2种榕树之间发生宿主转移的重要原因(刘桂香, 2013①; Liu et al, 2015)。
与早期随机性很强的基于野外观察和形态分类不同, Michaloud等(1985)的研究开启了综合植物学、昆虫学、分类学、生物化学、生态学、物候学等多学科证据来研究非一对一共生关系的新局面。越来越多的案例和证据使得学者们开始逐渐接受打破一对一原则的真实存在, 但质疑的声音仍在。例如, Wiebes (1994)仍然质疑传粉者共现现象, 指出更深入的分类学研究也许会证明具有2种或多种传粉者的榕树其实应该被进一步划分为2个或多个种或者亚种、变种等, 在榕树种或者种以下水平有各自专一的传粉者。
分子遗传标记技术的发展给榕树和传粉榕小蜂共生关系研究带来了革命性改变。理论上讲, 如果榕树和传粉榕小蜂之间存在严格的协同成种(cospeciation)和种水平上的一对一协同进化关系, 那么两者在系统发育树上应表现为一一对应的关系。然而事实并非如此。虽然早期的分子系统学研究(Herre et al, 1996; Machado et al, 2001; Weiblen, 2001; Weiblen & Bush, 2002)显示, 榕树与传粉榕小蜂具有较一致的系统发生关系, 但这些研究往往以少数甚至1个物种代表1个组或亚组, 忽略了高级分类阶元可能不是单系的问题(Rønsted et al, 2008); 以及仅用1个个体代表1个物种, 忽略隐存种的存在(Su et al, 2008)。例如, Su等(2008)通过对每个物种进行多样本采集而开展的系统发育研究发现了非一对一共生关系的存在。Cruaud等(2012)对全球范围内收集的近200个榕-传粉榕小蜂物种开展的分子系统学研究, 发现了大量宿主转移和重复成种事件。然而, 对一对一原则更为严竣的挑战来自于种群遗传学的研究和大量传粉榕小蜂隐存种的发现。
关于传粉榕小蜂隐存种的报道最早可追溯到Molbo等(2002)的研究。他们从巴拿马多株榕树植物F. obtusifolia上收集了800个小蜂样本, 它们在形态上都属于Pegoscapus hoffmeyeri, 而微卫星(simple sequence repeats, SSRs)数据支持存在2个P. hoffmeyeri隐存种。之后, Molbo等(2003)又对分布于巴拿马运河附近的8种榕树植物的传粉小蜂进行了采样, 发现来自于同种榕树的不同小蜂个体均属于同一形态种(morphospecies), 且均属于Pegoscapus属, 支持一对一原则; 而核基因微卫星数据分析显示, 其中4个形态种均存在2个隐存种; 线粒体基因COI分析显示, 同一形态种下不同隐存种之间的遗传分化大(4.2-6.6%)。结合COI的变异速率推算, 这些隐存种早在1.5-5.1百万年之前就已形成。同时, 还检测到榕树植物F. obtusifolia的2个小蜂隐存种之间存在低频率的杂交, 但未发现回交和基因渗入信号。高达50%的发生率显示隐存种的出现并非偶然, 至少在Pegoscapus属中具有普遍性。值得一提的是, 该研究在作为外类群的小蜂Tetrapus americanus中也检测到了隐存种, 而Tetrapus属被认为是传粉榕小蜂中最原始的类群(Machado et al, 2001; Weiblen, 2001; Weiblen & Bush, 2002; Cruaud et al, 2010), 暗示隐存种反复出现于榕-传粉榕小蜂系统的协同进化历史中。同时, COI数据还显示, 有些形态种(例如F. obtusifolia的传粉者P. hoffmeyeri)的2个隐存种为姊妹种关系, 暗示它们起源于同一宿主; 而另外一些形态种(例如F. popenoei的传粉者P. gemellus)的2个隐存种明显不为姊妹种, 表明其中1个隐存种必然来自于宿主转移。P. gemellus的1个隐存种被F. popenoei和F. bullenei共享的现象, 也进一步支持了宿主转移的存在, 但可能还处于宿主转移早期阶段(Molbo et al, 2003), 导致它在2个宿主间未出现明显的形态分化。
通过对澳洲东部沿海18个自然分布点和美国圣地亚哥1个引种点的F. rubiginosa传粉榕小蜂开展研究, Haine等(2006)发现形态上属于Pleistodontes imperialis的小蜂样本, 在Cytb基因树上形成4个独立分支(Clades 1-4)。分支间遗传分化(9-17%)远大于分支内分化(0-7%), 而形态上能够明显区分的Pleistodontes属下种间的遗传分化为10-26%, 支持4个不同分支为4个隐存种, 并表现为姊妹种关系, 它们在4.4-7.1百万年前发生物种分化。Clade 1广布于整个分布区, 也是唯一出现在引种区的类型; Clade 2限于昆士兰北部Townsville地区, Clade 3限于昆士兰北部, Clade 4广布于昆士兰。昆士兰境内的多数采样点均发现有2个或以上的隐存种。所有样本均检测到Wolbachia感染, 为3个Wolbachia菌系(W1-3)。Clade 3被菌系W1感染, Clade 1, 2, 4同时被W2和W3感染。Wolbachia感染和地理隔离一定程度上促进了传粉榕小蜂的物种分化, 但难以解释昆士兰地区不同隐存种的分化和共现机制。在Haine等(2006)基础上, Darwell等(2014)进行了更广泛的采样, 发现了第5个P. imperialis隐存种。Sutton等(2017)进一步综合COI和Cytb基因以及核基因微卫星数据, 对Townsville地区的P. imperialis种群开展了研究。结果支持该地区存在3个隐存种, 其中13%的榕果有2个或全部3个隐存种。虽然检测到几个疑似杂交个体, 但未发现基因渗入证据, 显示共现的隐存种之间存在明显的生殖隔离。Moe和Weiblen (2010)在亚洲热带至澳洲北部采集了6种榕树的传粉榕小蜂样本, 发现同种榕树不同分布区采集的小蜂样本均属于同一形态种。然而, COI数据显示6个形态种内均存在隐存种, 不同的隐存种有各自独立的分布区, 表明异域成种可能是其隐存种分化的重要机制。
国内学者对榕小蜂隐存种也开展了相关研究。Lin等(2011)对台湾岛分布的棱果榕(F. septica)传粉榕小蜂Ceratosolen bisulcatus进行了样本采集, 根据体表颜色将其分为黑色和黄色两类, 黑色类型广布于台湾岛, 而黄色类型只发现于台湾岛南部。南部采样点中, 两类小蜂共现于27%的榕果, 黑色和黄色各独占38%和35%的榕果。而COI数据显示小蜂分化为3个强烈支持的单系分支, 黄色类型为1支, 黑色类型分化为2支, 2支之间遗传分化较大(7.2%), 明显属于2个隐存种。核基因微卫星数据也支持3个分支之间存在显著分化(Lin et al, 2011)。Sun等(2011)从海南和福建不同分布点的9株小叶榕上采集了67个小蜂样本, 它们在形态上均属于Eupristina verticillata, 而COI和ITS2序列支持存在3个隐存种。三者分布区没有明显隔离, 但其中2个隐存种分别被不同的Wolbachia菌系感染, 第3个隐存种未被感染。分子钟推算显示, 2种Wolbachia菌系的分化时间要早于对应的2种小蜂隐存种的分化时间, 暗示Wolbachia感染可能诱导了小蜂的分化(Sun et al, 2011)。Chen等(2012)对分布于中国东南部的薜荔(F. pumila var. pumila)传粉者Wiebesia pumilae进行了研究, 发现形态上归于W. pumilae的样本显著地分化为3个分支, 分支间COI基因的遗传分化(7.2- 11.6%)远大于分支内分化(0.6-0.8%), 符合根据条形码COI划分为不同物种的标准(Hebert et al, 2003, 2004), 但宿主榕树植物却没有相应的分化。不同隐存种在邻接分布区存在同株共现现象, 但几乎不能共现于同一榕果, 从大的范围上来看, 表现为隔离分布格局(Chen et al, 2012; 刘敏, 2014), 生殖隔离明显, 未出现隐存种杂交情况(Liu et al, 2014)。进一步研究发现同域分布的不同W. pumilae隐存种之间存在物候分化, 特别是后代小蜂在羽化和飞出榕果的时间上存在分化, 这可能是其共现和生殖隔离的重要机制(Liu et al, 2014)。Yang等(2015)对西双版纳热带雨林地区1.5 km2范围内15种榕树的传粉榕小蜂进行了样本采集, COI和28S序列分析显示垂叶榕(F. benjamina)、青藤公(F. langkokensis)和鸡嗉子榕(F. semicordata)各自的小蜂形态种均包含2个隐存种。Yang等(2015)进一步采用整合分析(meta-analysis), 综合已发表数据, 对119对榕-传粉榕小蜂组合(89组雌雄同株种类, 30组雌雄异株种类)进行分析, 结果显示其中41种榕树存在多种传粉者, 其发生率在雌雄同株(31.5%)和雌雄异株榕树(43.3%)之间无显著差异。然而共现于雌雄异株榕树的不同传粉者之间均表现为姊妹种关系, 这一比例在雌雄同株榕树中仅为32.1%, 暗示榕树的性系统不同, 其传粉者共现现象的发生机制也不同。据此Yang等(2015)提出: 雌雄异株榕树的不同传粉者主要来自于重复成种, 而雌雄同株榕树的不同传粉者多来源于宿主转移。
共现的不同传粉者之间在不同的榕-传粉榕小蜂组合中进化出了不同的受精前隔离机制, 包括地理隔离(Michaloud et al, 1996; Haine et al, 2006; Moe & Weiblen, 2010; Chen et al, 2012)、行为隔离(Galil & Eisikowitch, 1968, 1969; Warren et al, 2010)、生态隔离(Michaloud et al, 1996; Chen et al, 2012)、生理隔离(Haine, 2006; Sun et al, 2011)等。虽然共现的隐存种小蜂之间有疑似杂交个体被检出, 但未发现基因渗入信号(Molbo et al, 2003; Sutton et al, 2017), 暗示还存在明显的受精后隔离, 但受精后的隔离机制还需要更深入的研究。
共享传粉者现象可能导致不同宿主间的杂交和基因渐渗, 但在不同榕-传粉榕小蜂组合中表现不同。例如, 在一些案例中未检测到榕树杂交信号(Ramírez, 1970b), 而在另外一些案例中检测到了杂交信号和杂交种(Parrish et al, 2003; Tsai et al, 2015), 显示不同榕树类群之间存在不同程度的生殖隔离。目前对榕树种间杂交的研究很少, 对其种间存在的生殖隔离机制也不清楚。共享传粉者的不同宿主榕树如何维持自身遗传的独立性, 以及宿主的种间杂交和基因渐渗, 必将成为未来重要的研究方向。
小蜂隐存种的大量出现, 开启了对包括隐存种的成种机制、共现机制的研究以及生物多样性的重新评估, 同时对榕小蜂控制实验的开展也带来了新的问题。同一株甚至同一榕果内发现不同隐存种, 说明传粉榕小蜂与宿主之间并非同时发生分化并协同成种, 其具体成种机制应该更为复杂。共现于同一榕果的不同隐存种在形态功能上高度相似, 关系近缘, 占据相似的生态位, 对其共现机制的研究也必然成为未来研究的重要方向之一。有研究(Zhang & Hanski, 1998; Zhang et al, 2004)提出“性比率选择”共存机制, 来解释这种隐存种的疑似共存现象, 对物种共存进行了理论探讨。该理论综合考虑种群的数量动态和进化动态, 只要求稀有种的性比率比常见种更偏雌, 而不需要任何形式的生态位分化, 但还未得到验证, 最大的困难在于难以确定共现的不同隐存种是否占据同一生态位。同时, 小蜂隐存种的高频率出现也提醒我们: (1)仅仅1个或少数几个小蜂样本不能代表整个榕-传粉榕小蜂系统; (2)榕小蜂和其他昆虫的物种多样性可能被严重低估(Cook & Rasplus, 2003; Bruno & Cardinale, 2008; Cook & Segar, 2010)。此外, 隐存种的存在表明, 仅采用形态特征进行物种鉴定具有很大的局限性, 这对开展人工控制实验带来了诸多困难。榕-传粉榕小蜂组合适合开展人工控制实验, 用于检验生态学、进化生物学等学科的重要理论, 而隐存种的存在可能会降低这些控制实验的有效性(Bickford et al, 2007), 须引起注意。
榕树有雌雄同株和雌雄异株之分, 早期研究发现传粉者共现多发生于雌雄同株榕树(Cook & Segar, 2010), 然而这些研究集中在只有雌雄同株榕树分布的美洲和非洲地区, 存在抽样不平衡的问题。后来对亚洲分布的雌雄异株榕树开展研究, 同样发现了传粉者共现现象(Lin et al, 2011; Chen et al, 2012; Yang et al, 2015), 其发生率在雌雄同株和雌雄异株榕树之间并无显著差异, 但发生机制存在差异(Yang et al, 2015)。而共享传粉者的报道较少, 主要发生于雌雄同种榕树, 在雌雄异株榕树上的发生率较低(Cook & Segar, 2010; Moe et al, 2011)。在已报道的25例共享传粉者案例中, 有17例发生于雌雄同株榕树, 是雌雄异株榕树的2倍(Wachi et al, 2016)。雌雄异株榕树的不同传粉者多为姊妹种关系, 且具有更低的共享传粉者发生率, 暗示雌雄异株榕树传粉者的宿主专一性要高于雌雄同株榕树传粉者。Yang等(2015)提出了2个假设来解释这种现象: (1)雌雄异株榕树具有更强的受精前隔离机制, 主要表现在传粉者对雌雄异株榕树物种的榕果挥发物具有更高区分度; (2)雌雄异株榕树传粉者发生宿主识别错误需要付出更高的适合度代价(fitness cost)。因此, 宿主转移事件不太容易发生于雌雄异株榕树, 但还需要更多的研究进行验证。未来对榕果挥发物、传粉榕小蜂的化学感受器(主要是触角)以及气味结合蛋白、化学感受蛋白等在榕-传粉榕小蜂系统中的演化机制和规律开展研究, 对于认识其共生关系的专性程度和进化具有重要意义。
本文分3个阶段综述了榕-传粉榕小蜂系统非一对一共生关系的研究进展, 并对未来研究进行了展望。虽然一对一原则在某些榕-传粉榕小蜂组合中依然适用, 但研究的深入、技术的革新以及数据的积累, 逐步打破了一对一原则的普适性。一对一和非一对一共生关系同时存在, 表明严格和发散两种协同进化模式并存于榕-传粉榕小蜂系统(陈艳等, 2010)。通过对榕树及其传粉者一对一共生关系的建立、维持以及打破机制的综合研究才能让我们越来越接近这对生死相依的物种间关系的真相。榕树与其传粉者之间的协同进化并不是严格、同步的简单重复过程。每一个榕-传粉榕小蜂组合都有其独特性, 都有各自特有的协同进化机制。750余种榕树意味着750余种协同进化关系的变体, 为研究进化生物学的一些基本问题和理论提供了优良的实验模型和丰富的素材。全球丰富多彩的生物类型是生物协同进化的结果, 通过对榕-传粉榕小蜂系统开展研究, 对探讨动植物之间的种种协同作用, 正确认识生物界内在的关系具有重要意义; 对包括具有专一性协同作用的丝兰-丝兰蛾、算盘子-头细蛾等体系, 以及自然界普遍存在发散性协同作用的生物类群之间的种种相互关系都具有重要的参考价值。
作者声明没有竞争性利益冲突.
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The taxonomic challenge posed by cryptic species (two or more distinct species classified as a single species) has been recognized for nearly 300 years, but the advent of relatively inexpensive and rapid DNA sequencing has given biologists a new tool for detecting and differentiating morphologically similar species. Here, we synthesize the literature on cryptic and sibling species and discuss trends in their discovery. However, a lack of systematic studies leaves many questions open, such as whether cryptic species are more common in particular habitats, latitudes or taxonomic groups. The discovery of cryptic species is likely to be non-random with regard to taxon and biome and, hence, could have profound implications for evolutionary theory, biogeography and conservation planning.
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The fig wasp fauna of the receptacles of Ficus thonningii (Hymenoptera, Chalcidoidea) .URL 摘要
THE FIG WASP FAUNA OF THE RECEPTACLES OF FICUS THONNINGII (HYMENOPTERA, CHALCIDOIDEA) by Z. BOUCEK 1 ), A. WATSHAM 2 ) and J. T. WIEBES 3 ) With 158 text-figures and four colour-plates Abstract Records and descriptions of the chalcids reared from the receptacles of Ficus thonningii Bl. (burkei (Miq.) Miq., petersii Warb.) mainly in Zimbabwe-Rhodesia, among which the following new species: Camarothorax brevimucro Boucek, spec, nov.; equicollis Boucek, spec, nov.; longimu-cro Boucek, spec. nov. — Crossogaster odorans Wiebes, spec. nov. — Eurytoma ficusgallae Boucek, spec. nov. — Ficomila Boucek, gen. nov., type-species Ficomila curtivena Boucek, spec, nov.; gambiensis (Risbec) Boucek, comb. nov. from Decatoma. — Otitesella tsamvi Wiebes, spec. nov. — Ormyrus flavipes Boucek, spec, nov.; subconicus Boucek, spec, nov.; watshami Boucek, spec. nov. — Philotrypesis parca Wiebes, spec. nov. — Syceurytoma Boucek, gen. nov., type-species Syceurytoma ficus Boucek, spec. nov. — Sycophila flaviclava Boucek, spec, nov.; kestraneura (Masi) Boucek, comb. nov. from Decatoma; modesta Boucek, spec, nov.; naso Boucek, spec, nov.; punctum Boucek, spec, nov.; sessilis Boucek, spec. nov. — Sycoryctes hirtus Wiebes, spec, nov.; remus Wiebes, spec. nov. — Sycoscapter cornutus Wiebes, spec. nov. — Sycotetra Boucek, gen. nov., type-species Sycotetra serricornis Boucek, spec. nov. — Watshamiel-la Wiebes, gen. nov., type-species Watshamiella alata Wiebes, spec. nov. — The following known species are recorded from the receptacles of Ficus thonningii: Alfonsiella brongersmai Wiebes; longiscapa Joseph. — Elisabethiella stuckenbergi (Grandi). — Phagoblastus barbarus Grandi. — The following new species and combinations originate from other localities: Camarothorax africanus (Wiebes) Boucek, comb. nov. from Sycobia (ex Ficus cf. eriobotryoides K. & B., Sierra Leone); imerinensis (Risbec) Boucek, comb. nov. from Callimomus (Malagasy); orientalis (Wiebes) Boucek, comb. nov. from Sycobia (ex Ficus reflexa Thunb., Aldabra). — Ormyrus chevalieri (Risbec) Boucek, comb. nov. from Monobaeus; decaryi (Risbec) Boucek, comb. nov. from Tribaeus. — Sycophila, new combinations, all from Decatoma: aethiopica (Silvestri) Boucek; cassinopsisi (Risbec) Boucek); nigrofasciata (Risbec) Boucek; ruandensis (Risbec) Boucek; rubra (Risbec) Boucek; xiphigaster (Risbec) Boucek. — Watshamiella infida Wiebes, spec. nov. (ex. Ficus religiosa L., Sri Lanka); salifera (Wiebes) Wiebes, comb. nov. from Sycoscapteridea (ex Ficus stupenda Miq. , North Borneo). A key is given to the chalcids associated with the receptacles of F. thonningii, irrespectively whether coming from evidently galled ones or not. The species having a closer association with the fig, especially the pollinators, are also mentioned in the introductory description of the fig cycle and the chalcid wasp fauna of the best studied species of Ficus are reviewed. *) Commonwealth Institute of Entomology, c/o British Museum (Natural History), London, England. 2 ) St. Ignatius College, Salisbury, Zimbabwe-Rhodesia. 3 ) c/o Rijksmuseum van Natuurlijke Historie, Raamsteeg 2, Leiden, The Netherlands (requests for reprints to be sent to this address). 149
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Cascading effects of predator richness .https://doi.org/10.1890/070136 URL [本文引用: 1] 摘要
Biologists have long known that predators play a key role in structuring ecological communities, but recent research suggests that predator richness - the number of genotypes, species, and functional groups that comprise predator assemblages - can also have cascading effects on communities and ecosystem properties. Changes in predator richness, including the decreases resulting from extinctions and the increases resulting from exotic invasions, can alter the composition, diversity, and population dynamics of lower trophic levels. However, the magnitude and direction of these effects are highly variable and depend on environmental context and natural history, and so are difficult to predict. This is because species at higher trophic levels exhibit many indirect, non-additive, and behavioral interactions. The next steps in predator biodiversity research will be to increase experimental realism and to incorporate current knowledge about the functional role of predator richness into ecosystem management.
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| [7] |
Fig trees at the northern limit of their range: The distributions of cryptic pollinators indicate multiple glacial refugia .https://doi.org/10.1111/j.1365-294X.2012.05491.x URL PMID: 22335780 [本文引用: 4] 摘要
Abstract Climatic oscillations during the last few million years had well-documented effects on the distributions and genomes of temperate plants and animals, but much less is known of their impacts on tropical and subtropical species. In contrast to Europe and North America, ice-sheets did not cover most of China during glacial periods, and the effects of glacial cycles were less dramatic. Fig trees are a predominantly tropical group pollinated by host-specific fig wasps. We employed partial mitochondrial COI (918090003bp) and nuclear ITS2 (462090003bp) gene sequences to investigate the genetic structure and demographic histories of the wasps that pollinate the subtropical Ficus pumila var. pumila in Southeastern China. Deep genetic divergence in both mitochondrial (7.2-11.6%) and nuclear genes (1.6-2.9%) indicates that three pollinator species are present and that they diverged about 4.72 and 6.00090003Myr bp. This predates the Quaternary ice ages, but corresponds with the formation of the Taiwan Strait and uplifting of the Wuyi-Xianxia Mountains. The three pollinators have largely allopatric distribution patterns in China and display different postglacial demographic histories. Wiebesia spp. 1 and 2 occupy, respectively, the northern and southern regions of the mainland host range. Their populations both underwent significant postglacial spatial expansions, but at different times and at different rates. Wiebesia sp. 3 is largely restricted to northern islands and shows less evidence of recent population expansion. Their mainly allopatric distributions and different demographic histories are consistent with host plant postglacial expansion from three distinct refugia and suggest one mechanism whereby fig trees gain multiple pollinators. 0008 2012 Blackwell Publishing Ltd.
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Species-specificity and coevolution of figs and their pollinating wasps .https://doi.org/10.3724/SP.J.1003.2010.001 URL [本文引用: 1] 摘要
共生体系的长期维持引发了一系列进化问题,特别是共生双方的相互适应、协同进化成为进化理论的一大挑战.榕和传粉榕小蜂是目前所知的专性最强的共生体系之 一,两者异常丰富的物种组成以及宿主多样的生活型为以上问题的研究提供了理想的体系.早期认为榕与其传粉小蜂间均为狭义协同进化,一对一原则在该体系中具 有普适性.然而近年来发现越来越多的例外,特别是宿主转移现象在某些地区、某些榕属类群中的普遍存在,使榕及其传粉小蜂间严格的物种专一性及协同进化发生 在物种水平的观点受到质疑,最近提出了一个新的协同进化模式来解释榕与其传粉小蜂的对应关系.榕与传粉小蜂间的进化模式说明两者问既有狭义的协同进化,也 有发散协同进化关系,从而导致它们之间物种专一性不同.目前,两种协同进化模式在该系统中的相对重要性仍存在很大争议,不同地区、不同榕属类群中两者的物 种专一性程度和产生原因可能有很大差异,榕与传粉榕小蜂系统的复杂性决定了不能将某些地区和某些类群的结论简单扩展,有关该体系协同进化主导模式的正确评 判有待于对不同地区和不同榕属类群对应传粉小蜂的物种组成、来源方式,以及共生双方的系统发生关系进行更广泛、更深入的研究.
榕-传粉榕小蜂间的专一性与协同进化 .https://doi.org/10.3724/SP.J.1003.2010.001 URL [本文引用: 1] 摘要
共生体系的长期维持引发了一系列进化问题,特别是共生双方的相互适应、协同进化成为进化理论的一大挑战.榕和传粉榕小蜂是目前所知的专性最强的共生体系之 一,两者异常丰富的物种组成以及宿主多样的生活型为以上问题的研究提供了理想的体系.早期认为榕与其传粉小蜂间均为狭义协同进化,一对一原则在该体系中具 有普适性.然而近年来发现越来越多的例外,特别是宿主转移现象在某些地区、某些榕属类群中的普遍存在,使榕及其传粉小蜂间严格的物种专一性及协同进化发生 在物种水平的观点受到质疑,最近提出了一个新的协同进化模式来解释榕与其传粉小蜂的对应关系.榕与传粉小蜂间的进化模式说明两者问既有狭义的协同进化,也 有发散协同进化关系,从而导致它们之间物种专一性不同.目前,两种协同进化模式在该系统中的相对重要性仍存在很大争议,不同地区、不同榕属类群中两者的物 种专一性程度和产生原因可能有很大差异,榕与传粉榕小蜂系统的复杂性决定了不能将某些地区和某些类群的结论简单扩展,有关该体系协同进化主导模式的正确评 判有待于对不同地区和不同榕属类群对应传粉小蜂的物种组成、来源方式,以及共生双方的系统发生关系进行更广泛、更深入的研究.
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Studies on Ceratosolen galili, a non-pollinating Agaonid fig wasp .https://doi.org/10.2307/2388305 URL [本文引用: 1] 摘要
The African fig tree Ficus sycomorus is host to two species of agaonid fig wasps, Ceratosolen arabicus and C. galili. Our studies of C. galili in southern Africa confirm that it does not actively pollinate the figs of F. sycomorus, although some accidental pollination takes place. The absence of pollination behavior in C. galili raises questions about the reasons why other agaonids pollinate the figs and thereby maintain the fig-fig wasp mutualism. C. galili larvae did not suffer elevated mortality rates when developing in unpollinated flowers and the only potential "cost" of not pollinating that we detected was that adult female C. galili were smaller than those of C. arabicus that developed on the same tree.
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Mutualists with attitude: Coevolving fig wasps and figs .https://doi.org/10.1016/S0169-5347(03)00062-4 URL [本文引用: 1] 摘要
The intimate mutualism between fig wasps and figs has long captivated biologists, and new phylogenies are now uncovering its evolutionary history. Fig-pollinating wasps evolved just once, but fig parasitism has evolved repeatedly and convergently. Figs and their pollinators appear to have co-speciated considerably, but not invariably, because the famous one-to-one rule of specificity is often broken. Some key traits of figs and pollinators show impressive correlated evolution, but the resolution of conflicts that threaten the stability of the mutualism remains controversial.
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| [11] |
Speciation in fig wasps .https://doi.org/10.1111/een.2010.35.issue-s1 URL [本文引用: 3] |
| [12] |
Check-list of Ficus in Asia and Australasia, with keys to identification . |
| [13] |
Floral volatiles, pollinator sharing and diversification in the fig-wasp mutualism: Insights from Ficus natalensis, and its two wasp pollinators (South Africa) .https://doi.org/10.1098/rspb.2011.1972 URL PMID: 22130605 [本文引用: 1] 摘要
Combining biogeographic, ecological, morphological, molecular and chemical data, we document departure from strict specialization in the fig-pollinating wasp mutualism. We show that the pollinating wasps Elisabethiella stuckenbergi and Elisabethiella socotrensis form a species complex of five lineages in East and Southern Africa. Up to two morphologically distinct lineages were found to co-occur locally in the southern African region. Wasps belonging to a single lineage were frequently the main regional pollinators of several Ficus species. In South Africa, two sister lineages, E. stuckenbergi and E. socotrensis, pollinate Ficus natalensis but only E. stuckenbergi also regularly pollinates Ficus burkei. The two wasp species co-occur in individual trees of F. natalensis throughout KwaZulu-Natal. Floral volatile blends emitted by F. natalensis in KwaZulu-Natal were similar to those emitted by F. burkei and different from those produced by other African Ficus species. The fig odour similarity suggests evolutionary convergence to attract particular wasp species. The observed pattern may result from selection for pollinator sharing among Ficus species. Such a process, with one wasp species regionally pollinating several hosts, but several wasp species pollinating a given Ficus species across its geographical range could play an important role in the evolutionary dynamics of the Ficus-pollinating wasp association.
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| [14] |
Laying the foundations for a new classification of Agaonidae (Hymenoptera: Chalcidoidea), a multilocus phylogenetic approach .https://doi.org/10.1111/j.1096-0031.2009.00291.x URL [本文引用: 1] 摘要
A phylogeny of the Agaonidae (Chalcidoidea) in their restricted sense, pollinators of Ficus species (Moraceae), is estimated using 4182 nucleotides from six genes, obtained from 101 species representing 19 of the 20 recognized genera, and four outgroups. Data analysed by parsimony and Bayesian inference methods demonstrate that Agaonidae are monophyletic and that the previous classification is not supported. Agaonidae are partitioned into four groups: (i) Tetrapus, (ii) Ceratosolen + Kradibia, (iii) some Blastophaga + Wiebesia species, and (iv) all genera associated with monoecious figs and a few Blastophaga and Wiebesia. The latter group is subdivided into subgroups: (i) Pleistodontes, (ii) Blastophaga psenes and neocaledonian Dolichoris, (iii) some Blastophaga and Wiebesia species, and (iv) Platyscapa, all afrotropical genera and all genera associated with section Conosycea. Eleven genera were recovered as monophyletic, six were para- or polyphyletic, and two cannot be tested with our data set. Based on our phylogeny we propose a new classification for the Agaonidae. Two new subfamilies are proposed: Tetrapusiinae for the genus Tetrapus, and Kradibiinae for Ceratosolen + Kradibia. Liporrhopalum is synonymized with Kradibia and the subgenus Valisia of Blastophaga is elevated to generic rank. These changes resulted in 36 new combinations. Finally, we discuss the hypothesis of co-speciation between the pollinators and their host species by comparing the two phylogenies.漏 The Willi Hennig Society 2009.
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An extreme case of plant-insect co-diversification: Figs and fig-pollinating wasps .https://doi.org/10.1093/sysbio/sys068 URL PMID: 22848088 [本文引用: 1] 摘要
It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent phylogenetic comparisons have supported this model of diversification for both insect herbivores and specialized pollinators. An exceptional case where contemporaneous plant-insect diversification might be expected is the obligate mutualism between fig trees (Ficus species, Moraceae) and their pollinating wasps (Agaonidae, Hymenoptera). The ubiquity and ecological significance of this mutualism in tropical and subtropical ecosystems has long intrigued biologists, but the systematic challenge posed by >750 interacting species pairs has hindered progress toward understanding its evolutionary history. In particular, taxon sampling and analytical tools have been insufficient for large-scale cophylogenetic analyses. Here, we sampled nearly 200 interacting pairs of fig and wasp species from across the globe. Two supermatrices were assembled: on an average, wasps had sequences from 77% of 6 genes (5.6 kb), figs had sequences from 60% of 5 genes (5.5 kb), and overall 850 new DNA sequences were generated for this study. We also developed a new analytical tool, Jane 2, for event-based phylogenetic reconciliation analysis of very large data sets. Separate Bayesian phylogenetic analyses for figs and fig wasps under relaxed molecular clock assumptions indicate Cretaceous diversification of crown groups and contemporaneous divergence for nearly half of all fig and pollinator lineages. Event-based cophylogenetic analyses further support the codiversification hypothesis. Biogeographic analyses indicate that the present-day distribution of fig and pollinator lineages is consistent with a Eurasian origin and subsequent dispersal, rather than with Gondwanan vicariance. Overall, our findings indicate that the fig-pollinator mutualism represents an extreme case among plant-insect interactions of coordinated dispersal and long-term codiversification. [Biogeography; coevolution; cospeciation; host switching; long-branch attraction; phylogeny.].
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Molecular species delimitation of a symbiotic fig-pollinating wasp species complex reveals extreme deviation from reciprocal partner specificity .https://doi.org/10.1186/s12862-014-0189-9 URL PMID: 4172794 [本文引用: 1] 摘要
Background Symbiotic relationships have contributed to major evolutionary innovations, the maintenance of fundamental ecosystem functions, and the generation and maintenance of biodiversity. However, the exact nature of host/symbiont associations, which has important consequences for their dynamics, is often poorly known due to limited understanding of symbiont taxonomy and species diversity. Among classical symbioses, figs and their pollinating wasps constitute a highly diverse keystone resource in tropical forest and savannah environments. Historically, they were considered to exemplify extreme reciprocal partner specificity (one-to-one host-symbiont species relationships), but recent work has revealed several more complex cases. However, there is a striking lack of studies with the specific aims of assessing symbiont diversity and how this varies across the geographic range of the host. Results Here, we use molecular methods to investigate cryptic diversity in the pollinating wasps of a widespread Australian fig species. Standard barcoding genes and methods were not conclusive, but incorporation of phylogenetic analyses and a recently developed nuclear barcoding gene (ITS2), gave strong support for five pollinator species. Each pollinator species was most common in a different geographic region, emphasising the importance of wide geographic sampling to uncover diversity, and the scope for divergence in coevolutionary trajectories across the host plant range. In addition, most regions had multiple coexisting pollinators, raising the question of how they coexist in apparently similar or identical resource niches. Conclusion Our study offers a striking example of extreme deviation from reciprocal partner specificity over the full geographical range of a fig-wasp system. It also suggests that superficially identical species may be able to co-exist in a mutualistic setting albeit at different frequencies in relation to their fig host???s range. We show that comprehensive sampling and molecular taxonomic techniques may be required to uncover the true structure of cryptic biodiversity underpinning intimate ecological interactions.
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On the pollination ecology of Ficus sycomorus in East Africa .https://doi.org/10.2307/1934454 URL [本文引用: 3] 摘要
Pollination and seed setting in ficus sycomorus have been investigated in East Africa. Ficus sycomorus is monoecious, each fig bearing both male and female flowers. Inside the figs 6 sycophilous wasps develop: Ceratosolen arabicus, Ceratosolen galili and sycophaga sycomori (primary sycophiles), and Apocrypta sp., Eukoebelea sp. and Sycoryctes sp. (secondary sycophiles). The structure and behavior of these wasps and their bearing on pollination and seed productionare studied. Ceratosolen arabiacus is the legitimate pollinator of Ficus sycomorus. It oviposits chiefly into short-styled female flowers, thus ensuring seed setting in the long-styled ones. It is a mutualistic symbiont of the fig. Sycophaga sycomori oviposits into both short- and long-styled flowers, and does not cause seed setting. It is a competitor of Ceratosolen, but a parasite of the fig. Eukoebelea, Apocrypta and Sycoryctes are inquilines, making use of galls induced by the activity of the primary sycophiles. They do not interfere with seed production in pollinated flowers not occupied by Ceratosolen or Sycophaga.
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| [18] |
Further studies on the pollination in Ficus sycomorus L. (Hymenoptera, Clacidoidea, Agaonidae) . |
| [19] |
Gli Agaonini (Hymenoptera Chalcididae) raccolti nell’Africa occidentale dal Prof. F. Silvestri . |
| [20] |
Identification of some fig insects (Hymenoptera) from the British Museum (Natural History) .https://doi.org/10.1017/S0007485300045387 URL [本文引用: 1] 摘要
Through the kindness of my friend Dr. James Waterston, the Authorities of the British Museum have sent me for examination a certain number of preparations containing some fig insects from various parts of the world. One of the species in this material,Otitesella digitata, Westw., has already been studied and figured by me in a recent paper;* some of the others are dealt with below.
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Hyménopteres sycophiles récoltés aux iles Philippines par CF Baker, I. Agaonini . |
| [22] |
Deep mtDNA divergences indicate cryptic species in a fig-pollinating wasp .https://doi.org/10.1186/1471-2148-6-83 URL PMID: 1626083 [本文引用: 3] 摘要
Background Figs and fig-pollinating wasps are obligate mutualists that have coevolved for ca 90 million years. They have radiated together, but do not show strict cospeciation. In particular, it is now clear that many fig species host two wasp species, so there is more wasp speciation than fig speciation. However, little is known about how fig wasps speciate. Results We studied variation in 71 fig-pollinating wasps from across the large geographic range of Ficus rubiginosa in Australia. All wasps sampled belong to one morphological species ( Pleistodontes imperialis ), but we found four deep mtDNA clades that differed from each other by 9鈥17% nucleotides. As these genetic distances exceed those normally found within species and overlap those (10鈥26%) found between morphologically distinct Pleistodontes species, they strongly suggest cryptic fig wasp species. mtDNA clade diversity declines from all four present in Northern Queensland to just one in Sydney, near the southern range limit. However, at most sites multiple clades coexist and can be found in the same tree or even the same fig fruit and there is no evidence for parallel sub-division of the host fig species. Both mtDNA data and sequences from two nuclear genes support the monophyly of the " P. imperialis complex" relative to other Pleistodontes species, suggesting that fig wasp divergence has occurred without any host plant shift. Wasps in clade 3 were infected by a single strain (W1) of Wolbachia bacteria, while those in other clades carried a double infection (W2+W3) of two other strains. Conclusion Our study indicates that cryptic fig-pollinating wasp species have developed on a single host plant species, without the involvement of host plant shifts, or parallel host plant divergence. Despite extensive evidence for coevolution between figs and fig wasps, wasp speciation may not always be linked strongly with fig speciation.
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| [23] |
Figs and the diversity of tropical rainforests .https://doi.org/10.1641/0006-3568(2005)055[1053:FATDOT]2.0.CO;2 URL [本文引用: 1] 摘要
Ficus(Moraceae) is arguably one of the most important plant genera in lowland tropical rainforests. A brief review of tropical florulas also demonstrates thatFicusis the only ubiquitously diverse genus in lowland rainforests. Monoecious hemiepiphytic figs, constituting independent radiations in each tropical biome, make up a significant proportion of species everywhere, but in Asia dioecious figs have diversified into a variety of niches, making the assemblages of this region especially speciose. Pioneer attributes have endowed figs with tremendous evolutionary flexibility, while long-range seed dispersal ensures that a high proportion of the regional species pool is represented in local assemblages. Large numbers ofFicusspecies are able to coexist because many are extremely rare as a result of limited recruitment opportunities, which limits competition. They are nevertheless able to breed at low densities because they possess an efficient, long-range pollination system. These factors are likely to be important in the diversity of other plant groups in the tropics.
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| [24] |
Barcoding animal life: Cytochrome c oxidase subunit 1 divergences among closely related species .https://doi.org/10.1098/rsbl.2003.0025 URL PMID: 12952648 [本文引用: 1] 摘要
Abstract With millions of species and their life-stage transformations, the animal kingdom provides a challenging target for taxonomy. Recent work has suggested that a DNA-based identification system, founded on the mitochondrial gene, cytochrome c oxidase subunit 1 (COI), can aid the resolution of this diversity. While past work has validated the ability of COI sequences to diagnose species in certain taxonomic groups, the present study extends these analyses across the animal kingdom. The results indicate that sequence divergences at COI regularly enable the discrimination of closely allied species in all animal phyla except the Cnidaria. This success in species diagnosis reflects both the high rates of sequence change at COI in most animal groups and constraints on intraspecific mitochondrial DNA divergence arising, at least in part, through selective sweeps mediated via interactions with the nuclear genome.
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| [25] |
Identification of birds through DNA barcodes .[本文引用: 1] 摘要 |
| [26] |
Molecular phylogenies of figs and their pollinator wasps .https://doi.org/10.1111/j.1365-2699.1996.tb00014.x URL [本文引用: 1] 摘要
We collected and analysed nucleotide sequence and protein electrophoretic data on order to estimate phylogenies of figs and fig-pollinating wasps at several taxonomic scales. The relatively conserved chloroplast gene coding rbCl allowed the estimation of the taxonomic position of Ficus relative to other genera within the Moraceae. Further, in conjuction with chloroplast tRNA spacer genes, rbcL sequences allowed the partial resolution of the phylogenetic associations of fig species from different parts of the world with representatives from all the recognized subgenera of Ficus. The phylogeny of the corresponding wasp species that pollinate most of those taxa was estimated using mitochondrial COI-COII and 12S ribosomal genes. At a fine scale, the phylogenies of species within two subgenera of figs growing in Panama (Urostigma, and Pharmacosyceae) were estimated by using protein electrophoretic data. The phylogeny of the corresponding pollinator wasp species was estimated using COII sequence data. Althouth we need to extend the taxa sampled and augment the molecular database, the host and pollinator phylogenies show a high degree of congruence and the results support the predominance of strict-sense co-evolution between figs and their pollinator wasps at both global and fine scales.
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| [27] |
How to be a fig .https://doi.org/10.1146/annurev.es.10.110179.000305 URL [本文引用: 1] |
| [28] |
A contribution to the morphology and embryology of Ficus religiosa Linn . |
| [29] |
Contributions to our knowledge of fig insects (Chalcidoidea: parasitic Hymenoptera) from India. IV. Descriptions of three new and records of four known species of Agaonini . |
| [30] |
Molecular phylogeny of the Ceratosolen species pollinating Ficus of the subgenus Sycomorus sensu stricto: Biogeographical history and origins of the species-specificity breakdown cases .https://doi.org/10.1006/mpev.1998.0590 URL [本文引用: 1] |
| [31] |
Active pollination of Ficus sur by two sympatric fig wasp species in West Africa .https://doi.org/10.1111/j.1744-7429.1997.tb00007.x URL [本文引用: 1] 摘要
Abstract ABSTRACT Ceratosolen silvestrianus and C. arabicus are two species of agaonine fig wasps that co-occur in the figs of Ficus sur in West Africa. Our work in the Ivory Coast shows that both are active pollinators, and that they may be found together in the same syconia. In our study area, C. silvestrianus is much more abundant than C. flabellatus . We found no competitive effect for oviposition sites on C. silvestrianus , and hypothesize that habitat preferences allow the coexistence of two sympatric active pollinators in the same Ficus host in the Ivory Coast. RESUMEN En Afrique de I'Ouest, deux espéces d'hyménoptéres Agaoninae, Ceratosolen silvestrianus et C. flabellatus , sont associées à Ficus sur Notre étude en C00re d'Ivoire a montré que toutes dew pollinisent activement, et peuvent se développer ensemble au sein d'une même figue. Dans notre lieu de récolte, C. silvestrianus est bien plus abondant que C. fibellatus . Nous n'avons pas mis en évidence pour C. silvestrianus , de co04t liéá la compétition avec C. flabellatus . La présence de deux pollinisateurs actifs sur un même site pourrait être due á I'existence d'une mosa07que d'habitats différents, abritant chacun préférentiellement une des deux espéces.
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| [32] |
The lack of pollinator specificity in a dioecious fig tree: Sympatric fig-pollinating wasps of Ficus septica in Southern Taiwan .https://doi.org/10.1111/j.1744-7429.2010.00686.x URL [本文引用: 2] 摘要
ABSTRACT Although species specificity between fig trees and their pollinators has been considered a classic example of obligate mutualism, increasing exceptions to the one-to-one relationship suggest that multiple pollinator species per fig host species may be a pervasive phenomenon. Based on both mitochondrial DNA and microsatellite analyses, we found three putative pollinator species ( Ceratosolen spp.) associated with Ficus spetica in southern Taiwan, two of which, that differ in color, routinely coexist within single figs. These three pollinators are substantially divergent from the pollinator of F. spetica in New Guinea, implying that wasp diversity may be highly underestimated when the one-to-one rule is assumed. Our findings not only provide the first case of coexistence of pollinators within single figs on a shared dioecious Ficus host, but also an ideal system to investigate interspecific competition and sex allocation, especially when coexisting pollinators are visually distinguishable by their colors.
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| [33] |
Complementary fruiting phenologies facilitate sharing of one pollinator fig wasp by two fig trees .https://doi.org/10.1093/jpe/rtv022 URL [本文引用: 1] 摘要
Aims Most pollinator fig wasps are host plant specific, with each species only breeding in the figs of one fig tree species, but increasing numbers of species are known to be pollinated by more than one fig wasp, and in rare instances host switching can result in Ficus species sharing pollinators. In this study, we examined factors facilitating observed host switching at Xishuangbanna in Southwestern (SW) China, where Ficus squamosa is at the northern edge of its range and lacks the fig wasps that pollinate it elsewhere, and its figs are colonized by a Ceratosolen pollinator that routinely breeds in figs of F. heterostyla. Methods We recorded the habitat preferences of F. squamosa and F. heterostyla at Xishuangbanna, and compared characteristics such as fig size, location and colour at receptive phase. Furthermore, the vegetative and reproductive phenologies in the populations of F. squamosa and F. heterostyla were recorded weekly at Xishuangbanna Tropical Botanical Garden for 1 year. Important Findings Ficus squamosa is a shrub found near fast-flowing rivers, F. heterostyla is a small tree of disturbed forest edges. Although preferring different habitats, they can be found growing close together. Both species have figs located at or near ground level, but they differ in size when pollinated. Fig production in F. squamosa was concentrated in the colder months. F. heterostyla produced more figs in summer but had some throughout the year. The absence of its normal pollinators, in combination with similarly located figs and partially complementary fruiting patterns appear to have facilitated colonization of F. squamosa by the routine pollinator of F. heterostyla. The figs probably also share similar attractant volatiles. This host switching suggests one mechanism whereby fig trees can acquire new pollinators and emphasizes the likely significance of edges of ranges in the genesis of novel fig tree-fig wasp relationships.
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| [34] |
Divergence and Comparative Phylogeography of Ficus pumila and Its Pollinating Wasps (Wiebesia spp.) .薜荔(Ficus pumila)及其传粉小蜂(Wiebesia spp.)的分化与比较亲缘地理学 . |
| [35] |
Competitive exclusion among fig wasps achieved via entrainment of host plant flowering phenology .https://doi.org/10.1371/journal.pone.0097783 URL PMID: 4029822 摘要
Molecular techniques are revealing increasing numbers of morphologically similar but co-existing cryptic species, challenging the niche theory. To understand the co-existence mechanism, we studied phenologies of morphologically similar species of fig wasps that pollinate the creeping fig (F. pumila) in eastern China. We compared phenologies of fig wasp emergence and host flowering at sites where one or both pollinators were present. At the site where both pollinators were present, we used sticky traps to capture the emerged fig wasps and identified species identity using mitochondrial DNA COI gene. We also genotyped F. pumila individuals of the three sites using polymorphic microsatellites to detect whether the host populations were differentiated. Male F. pumila produced two major crops annually, with figs receptive in spring and summer. A small partial third crop of receptive figs occurred in the autumn, but few of the second crop figs matured at that time. Hence, few pollinators were available to enter third crop figs and they mostly aborted, resulting in two generations of pollinating wasps each year, plus a partial third generation. Receptive figs were produced on male plants in spring and summer, timed to coincide with the release of short-lived adult pollinators from the same individual plants. Most plants were pollinated by a single species. Plants pollinated by Wiebesia sp. 1 released wasps earlier than those pollinated by Wiebesia sp. 3, with little overlap. Plants occupied by different pollinators were not spatially separated, nor genetically distinct. Our findings show that these differences created mismatches with the flight periods of the other Wiebesia species, largely 鈥榬eserving鈥 individual plants for the resident pollinator species. This pre-emptive competitive displacement may prevent long term co-existence of the two pollinators.
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| [36] |
Phylogenetic relationships, historical biogeography and character evolution of fig-pollinating wasps .https://doi.org/10.1098/rspb.2000.1418 URL [本文引用: 2] |
| [37] |
Relative investment in egg load and poison sac in fig wasps: Implications for physiological mechanisms underlying seed and wasp production in figs .https://doi.org/10.1016/j.actao.2013.07.009 URL [本文引用: 1] 摘要
61We measured relative investment in poison sac (ps) and eggs in 15 fig wasp species.61Relative investment in ps was less in pollinator than in non-pollinator wasps.61Relative investment in ps was usually higher active pollinators than in the passives.61We suggest one general mechanism accounts for mutualism stability of figs and wasps.
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| [38] |
Feigenwespen. Verhandlungen der Zoologisch-Botanischen Gesellschaft in Wien , |
| [39] |
Exceptions to the one : one relationship between African fig trees and their fig wasp pollinators: Possible evolutionary scenarios .https://doi.org/10.1111/j.1365-2699.1996.tb00013.x URL [本文引用: 5] 摘要
Abstract. The mutualistic breeding system involving fig trees (Moraceae, Ficus ) and fig wasps (Hymenoptera, Chalcidoidea, Agaoninae) would appear so specialized that one may wonder at the evolutionary processes that could be responsible for the existence of about 750 species-specific associations. In this paper we present data concerning two cases of species specificity breakdown between African fig trees and fig wasps. We then analyse the possible evolutionary scenarios which could be responsible, as well as the possible evolutionary outcomes of the observed situations. Our analyses range in scale from continental to habitats, and fig crops to individual figs (syconia). Habitat shifts and ecological barriers seem to be the more likely explanations for the evolution of novel fig tree-fig wasp associations, but sympatric and parapatric scenarios cannot be ruled out.
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| [40] |
The co-occurrence of two pollinating species of fig wasp and one species of fig. Proceedings of the Koninklijke Nederlandse Akademie van Wetenscahppen, |
| [41] |
Pollinator sharing in dioecious figs (Ficus: Moraceae) .https://doi.org/10.1111/j.1095-8312.2011.01669.x URL [本文引用: 1] 摘要
Abstract As one of the most specialized pollination syndromes, the fig ( Ficus )鈥揻ig wasp (Agaonidae) mutualism can shed light on how pollinator behaviour and specificity affect plant diversification through processes such as reproductive isolation and hybridization. Pollinator sharing among species has important implications for Ficus species delimitation and the evolutionary history of the mutualism. Although agaonid wasp pollinators are known to visit more than one host species in monoecious figs, pollinator sharing has yet to be documented in dioecious figs. The present study investigated the frequency of pollinator sharing among sympatric, closely-related dioecious figs in Ficus sections Sycocarpus and Sycidium . Molecular and morphological species identification established the associations between pollinating agaonid wasp species and host fig species. Cytochrome oxidase I was sequenced from 372 Ceratosolen pollinators of Ficus section Sycocarpus and 210 Kradibia pollinators of Ficus section Sycidium . The association between fig species and morphologically distinct clades of pollinator haplotypes was predominantly one-to-one. In Ceratosolen , six of 372 pollinators (1.5%) visited fig species other than the predominant host. No pollinator sharing was detected between the two Sycidium host species, although a rare hybrid shared Kradibia pollinators with both parental species. These findings point to low rates of pollinator sharing among closely-related dioecious fig species in sympatry, and perhaps lower rates than among monoecious figs. Such rare events could be evolutionarily important as mechanisms for gene flow among fig species. Differences in rates of pollinator sharing among fig lineages might explain the conflicting phylogenetic patterns inferred among monoecious figs, dioecious figs, and their respective pollinators.漏 2011 The Linnean Society of London, Biological Journal of the Linnean Society , 2011, 103 , 546鈥558.
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| [42] |
Molecular divergence in allopatric Ceratosolen (Agaonidae) pollinators of geographically widespread Ficus (Moraceae) species .https://doi.org/10.1603/AN10083 URL [本文引用: 1] 摘要
Speciation in pollinating seed predators such as fig wasps (Hymenoptera: Agaonidae) is likely to have been influenced by a combination of ecological and geographical isolating mechanisms, but recent molecular analyses of fig wasps have focused on pollinator specialization as the main factor driving speciation. This study investigates the contribution of geographic modes of speciation such as dispersal, vicariance, and isolation by distance. We sampled haplotypes of mitochondrial cytochrome oxidase I from Ceratosolen pollinators of six geographically widespread Australasian fig (Moraceae: Ficus) species, including four species spanning Wallacea. Phylogenetic analysis investigated the extent of host conservatism and host switching accompanying divergence in Ceratosolen Geographically widespread Ceratosolen showed deep intraspecific divergence exceeding or comparable to divergence between named sister species. Maximum parsimony and Bayesian analyses supported species monophyly in five of six cases, whereas results for a sixth species were equivocal. Bayesian divergence time estimation suggested dispersal across Wallacea during the Miocene epoch, after the collision of Australian and Asian continental plates. Cryptic species were evident in all six focal taxa. Because the deep mitochondrial divergence within these taxa is regionally distributed, allopatric divergence provides a simple explanation for the existence of these cryptic lineages pollinating widespread fig species. We found little evidence of divergence accompanied by host switching. The ancient origin of cryptic and geographically isolated species suggests that long-distance dispersal may be rare in Ceratosolen and that host associations are generally conserved during range expansion.
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| [43] |
Species-diagnostic microsatellite loci for the fig wasp genus Pegoscapus .https://doi.org/10.1046/j.1471-8286.2002.00268.x URL 摘要
Abstract To obtain tools for the estimation of inbreeding and assignment of offspring to matrilines, we developed 13 microsatellite loci from the fig wasps that pollinate Ficus obtusifolia . Based on morphological studies, it was thought that a single species ( Pegoscapus hoffmeyeri ) pollinated this fig.However, our data revealed the presence of two coexisting cryptic species. Several diagnostic microsatellite markers may be used to distinguish these two cryptic species. The new microsatellites can be used across a wide range of fig-pollinating wasp species for both evolutionary and population genetic studies.
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| [44] |
Cryptic species of fig-pollinating wasps: Implications for the evolution of the fig-wasp mutualism, sex allocation, and precision of adaptation .https://doi.org/10.1073/pnas.0930903100 URL PMID: 12714682 [本文引用: 2] 摘要
Fig-pollinating wasps have provided model systems for developing and testing theories of the evolution of mutualism, sex allocation, and precision of adaptation. With few exceptions, previous studies have assumed one species of pollinator wasp per host fig species. Here we report genetic data demonstrating the coexistence of previously undetected cryptic fig wasp species in at least half of the host fig species surveyed. The substantial mitochondrial sequence differences (4.2-6.1%) imply old divergences ( approximately 1.5-5.1 million years ago) among these species. Furthermore, some cryptic species pairs seem to be sister taxa, whereas others clearly are not, indicating both long-term coexistence on shared hosts and the colonization of novel fig species. These findings undermine the prevalent notion of strict one-to-one specificity between cospeciating figs and their pollinators, thereby challenging existing theory concerning the evolution and stability of mutualisms. Moreover, the incorporation of the genetic information significantly improves the fit of the observed sex ratios to predictions of local mate-competition theory, further strengthening support for sex allocation theory and the precision of adaptation.
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| [45] |
Feigenwespen . |
| [46] |
Genetic evidence for natural hybridization between species of dioecious Ficus on island populations .https://doi.org/10.1111/btp.2003.35.issue-3 URL [本文引用: 1] |
| [47] |
The reproductive success of Ficus altissima and its pollinator in a strongly seasonal environment: Xishuangbanna, Southwestern China .https://doi.org/10.1007/s11258-009-9690-4 URL [本文引用: 1] 摘要
Fig trees (Ficus spp.) are of great ecological significance, producing fruits that are fed on by more birds and mammals than any other plants in the tropics. They are pollinated by host-specific pollinator fig wasps (Hymenoptera, Agaonidae), and their fruit phenology and reproductive success are, therefore, modulated by symbiotic fig wasps. However, there are few studies focusing on the variation of Ficus reproductive success in strongly seasonal environments. We examined the phenology and reproductive success of Ficus altissima growing in a highly seasonal climate towards the northern limit of the range of fig trees in Xishuangbanna, China. Leaf production occurred at irregular intervals throughout the year, with new leaves and syconia initiated together, producing between three and seven crops over a 3-year period. Syconia were produced in synchronous crops with asynchrony between trees. The syconia produced more seeds than pollinators, and those syconia with more seeds also produced more pollinators. Reproductive success (measured as the number of seeds and pollen-carrying agaonid females produced by each syconium) varied greatly between seasons. It was highest for crops that matured during the cooler, relatively dry periods from February to March and October to November, and was lowest during the summer months from April to August. This variation corresponded to small differences in the number of flowers in the syconia, but was mainly driven by large seasonal differences in the relative abundance of non-pollinating fig wasps.
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| [48] |
Co-occurrence of two Eupristina species on Ficus altissima in Xishuangbanna, SW China . |
| [49] |
Seasonality of leaf and fig production in Ficus squamosa, a fig tree with seeds dispersed by water .https://doi.org/10.1371/journal.pone.0152380 URL PMID: 4807038 [本文引用: 1] 摘要
The phenology of plants reflects selection generated by seasonal climatic factors and interactions with other plants and animals, within constraints imposed by their phylogenetic history. Fig trees (Ficus) need to produce figs year-round to support their short-lived fig wasp pollinators, but this requirement is partially de-coupled in dioecious species, where female trees only develop seeds, not pollinator offspring. This allows female trees to concentrate seed production at more favorable times of the year.Ficus squamosais a riparian species whose dispersal is mainly by water, rather than animals. Seeds can float and travel in long distances. We recorded the leaf and reproductive phenology of 174 individuals for three years in Chiang Mai, Northern Thailand. New leaves were produced throughout the year. Fig production occurred year-round, but with large seasonal variations that correlated with temperature and rainfall. Female and male trees initiated maximal fig crops at different times, with production in female trees confined mainly to the rainy season and male figs concentrating fig production in the preceding months, but also often bearing figs continually.Ficus squamosaconcentrates seed production by female plants at times when water levels are high, favouring dispersal by water, and asynchronous flowering within male trees allow fig wasps to cycle there, providing them with potential benefits by maintaining pollinators for times when female figs become available to pollinate.
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| [50] |
Taxonomic and biological studies of neotropical fig wasps (Hymenoptera: Agaonidae) .https://doi.org/10.5962/bhl.part.9196 URL 摘要
Abstract Thesis (M.A.)--University of Kansas, Entomology, 1969. Includes bibliographical references (leaves 65-67).
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| [51] |
Host specificity of fig wasps (Agaonidae) .https://doi.org/10.1111/evo.1970.24.issue-4 URL [本文引用: 1] |
| [52] |
The one-to-one species-specificity of the Ficus-Agaoninae mutualism: How casual? In: The Biodiversity of African Plants (eds van der Maesen LJG, van der Burgt XM, van Medenbach de Rooy JM), pp . |
| [53] |
Reconstructing the phylogeny of figs (Ficus, Moraceae) to reveal the history of the fig pollination mutualisms .https://doi.org/10.1634/stemcells.2008-0642 URL [本文引用: 1] 摘要
Figs (Ficus, Moraceae) constitute one of the largest genera of flowering plants with ca. 750 species worldwide. While the extraordinary mutualism between figs and their pollinating wasps has received attention for decades, we are only just beginning to reconstruct the phylogeny of both partners, a necessary framework for addressing a variety of questions concerning the evolution of mutualism. H...
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| [54] |
Fig-eating by vertebrate frugivores: A global review .[本文引用: 1] 摘要 |
| [55] |
Breakdown of the one-to-one rule in Mexican fig-wasp associations inferred by molecular phylogenetic analysis .https://doi.org/10.1634/stemcells.2008-0642 URL [本文引用: 1] 摘要
The interaction between figs (Ficus spp., Moraceae) and fig-pollinating wasps (Chalcidoidea, Agaonidae) is one of the most species-specific cases of mutualism, and is a model system for studying coevolution and cospeciation between insects and plants. To test the specificity-breakdown hypothesis, we performed a phylogenetic analysis using mitochondrial COI gene sequences of Mexican fig-pollinat...
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| [56] |
Comparisons of host mitochondrial, nuclear and endosymbiont bacterial genes reveal cryptic fig wasp species and the effects of Wolbachia on host mtDNA evolution and diversity .https://doi.org/10.1186/1471-2148-11-86 URL [本文引用: 2] |
| [57] |
Local coexistence and genetic isolation of three pollinator species on the same fig tree species .https://doi.org/10.1038/hdy.2016.125 URL PMID: 28074845 [本文引用: 1] 摘要
An official journal of the Genetics Society, Heredity publishes high-quality articles describing original research and theoretical insights in all areas of genetics. Research papers are complimented by News & Commentary articles and reviews, keeping researchers and students abreast of hot topics in the field.
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| [58] |
A breakdown of obligate mutualism on a small island: An interspecific hybridization between closely related fig species (Ficus pumila and Ficus thunbergii) in Western Japan .https://doi.org/10.4236/ajps.2015.61014 URL [本文引用: 1] 摘要
Ficus (Moraceae) is a well-known group with specific pollination mutualisms, and hybridization is considered to be rare. Here, we report the presence of interspecific hybrids between Ficus pumila L. and F. thunbergii Maxim. on Okinoshima, a small island offshore of Shikoku, western Japan. AFLP (amplified fragment length polymorphism of genomic DNA) data suggested that more than one-fourth of individuals of morphological F. pumila were assigned as intermediate genotypes, suggesting hybrids. The hybridization between the two species was introgressive and unidirectional from F. thunbergii to F. pumila. The findings of this study, combined with other previous reports, suggest that the breakdown of mutualistic systems can occur in isolated populations such as those on islands.
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| [59] |
Genome-wide sequence data suggest the possibility of pollinator sharing by host shift in dioecious figs (Moraceae, Ficus) .https://doi.org/10.1111/mec.13876 URL PMID: 27706883 [本文引用: 1] 摘要
Abstract The obligate mutualism of figs and fig-pollinating wasps has been one of the classic models used for testing theories of co-evolution and cospeciation due to the high species-specificity of these relationships. To investigate the species-specificity between figs and fig pollinators and to further understand the speciation process in obligate mutualisms, we examined the genetic differentiation and phylogenetic relationships of four closely related fig-pollinating wasp species ( Blastophaga nipponica , Blastophaga taiwanensis , Blastophaga tannoensis and Blastophaga yeni ) in Japan and Taiwan using genome-wide sequence data, including mitochondrial DNA sequences. In addition, population structure was analysed for the fig wasps and their host species using microsatellite data. The results suggest that the three Taiwanese fig wasp species are a single panmictic population that pollinates three dioecious fig species, which are sympatrically distributed, have large differences in morphology and ecology and are also genetically differentiated. Our results illustrate the first case of pollinator sharing by host shift in the subgenus Ficus . On the other hand, there are strict genetic codivergences between allopatric populations of the two host鈥損ollinator pairs. The possible processes that produce these pollinator-sharing events are discussed based on the level and pattern of genetic differentiation in these figs and fig wasps.
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| [60] |
A comparative approach to understanding factors limiting abundance patterns and distributions in a fig tree-fig wasp mutualism .https://doi.org/10.1111/j.1600-0587.2009.06041.x URL [本文引用: 2] 摘要
Numerous factors affect distribution and abundance. Due to their intimate host association, pollinating fig wasps are expected to occupy the entire distribution of their host fig. An understanding of the physiology of fig wasp species and the factors affecting adult survival are important for understanding and explaining wasp abundance and distribution patterns. We examine distribution and abundance patterns of a fig tree芒聙聯fig wasp system in which the non-pollinator (Ceratosolen galili) has been reported to be rarer than the pollinator (Ceratosolenarabicus) in drier areas due to lower desiccation tolerance. Both species are closely related and utilise the same oviposition sites on Ficus sycomorus. We used ecological niche modelling to determine whether C. galili covers the range of F. sycomorus and whether it is consistently rarer than C. arabicus. We examined emergence times, critical thermal limits, desiccation and starvation tolerances of the wasps. The suggested rarity of C. galili relates to lower abundance in certain months and at certain localities but a similar number of occurrence records within the distributional range (except in arid regions, e.g. Namibia). In contrast to C. galili, C. arabicus has a wider thermal range, lives longer under hydrating and dehydrating conditions and is a nocturnal flier. The synergistic effect of physiological tolerances and flight time differences exacerbate the less favourable conditions available to C. galili during flight and location of receptive figs. These factors enable C. arabicus to survive for longer than C. galili, meaning that they are more likely to disperse to trees that are flowering further away in space and time. Combining correlative and mechanistic approaches has aided us in understanding the ecological niches of these species.
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| [61] |
Phylogenetic relationships of fig wasps pollinating functionally dioecious Ficus based on mitochondria DNA sequences and morphology .https://doi.org/10.1080/10635150120131 URL PMID: 12116930 [本文引用: 2] 摘要
Abstract The obligate mutualism between pollinating fig wasps in the family Agaonidae (Hymenoptera: Chalcidoidea) and Ficus species (Moraceae) is often regarded as an example of co-evolution but little is known about the history of the interaction, and understanding the origin of functionally dioecious fig pollination has been especially difficult. The phylogenetic relationships of fig wasps pollinating functionally dioecious Ficus were inferred from mitochondrial cytochrome oxidase gene sequences (mtDNA) and morphology. Separate and combined analyses indicated that the pollinators of functionally dioecious figs are not monophyletic. However, pollinator relationships were generally congruent with host phylogeny and support a revised classification of Ficus. Ancestral changes in pollinator ovipositor length also correlated with changes in fig breeding systems. In particular, the relative elongation of the ovipositor was associated with the repeated loss of functionally dioecious pollination. The concerted evolution of interacting morphologies may bias estimates of phylogeny based on female head characters, but homoplasy is not so strong in other morphological traits. The lesser phylogenetic utility of morphology than of mtDNA is not due to rampant convergence in morphology but rather to the greater number of potentially informative characters in DNA sequence data; patterns of nucleotide substitution also limit the utility of mtDNA findings. Nonetheless, inferring the ancestral associations of fig pollinators from the best-supported phylogeny provided strong evidence of host conservatism in this highly specialized mutualism.
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| [62] |
Speciation in fig pollinators and parasites .https://doi.org/10.1046/j.1365-294X.2002.01529.x URL PMID: 12144676 [本文引用: 2] 摘要
Here we draw on phylogenies of figs and fig wasps to suggest how modes of speciation may be affected by interspecific interactions. Mutualists appear to have cospeciated with their hosts to a greater extent than parasites, which showed evidence of host shifting. However, we also repeatedly encountered a pattern not explained by either cospeciation or host switching. Sister species of fig parasites often attack the same host in sympatry, and differences in ovipositor length suggest that parasite speciation could result from divergence in the timing of oviposition with respect to fig development. These observations on fig parasites are consistent with a neglected model of sympatric speciation.
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| [63] |
Taxonomy and host preferences of Indo-Australian fig wasps of the genus Ceratosolen (Agaonidae) .
.mi J" ^'10)983 TAXONOMY AND HOST PREFERENCES dF INDO-" AUSTRALIAN FIG WASPS OF THE GENUS CERATOSOLEN (AGAONIDAE) BY J. T. WIEBES Rijksmuseum van Natuurlijke Historie, Leiden Contents Introduction 1 The Indo-Malayan and Papuan species of the genus Ceratosolen 3 Taxonomie revision 3 Classification and key to the species 84 The host preferences of the Agaonidae 92 Specificity of the relation between fig wasps and figs 92 Phylogenetic specificity 99 Concluding remarks 105 References 106 Index 109 Introduction The systematic position of the fig wasps has for a long time been a challenging problem to biologists. Up to about 1880, the literature on fig wasps consisted of only a few occasional papers on the curious creatures found in the receptacles of 楼icus species, and on the function they were supposed to fulfil, or were denied to have, in the process of caprification. For a survey of the literature prior to 1880, I refer to the critical review by Mayer (1882). Saunders (from 1878 onwards) and Westwood (1882, 1883) described a number of genera and species of fig wasps from India and Australia. Paul Mayer (1882) reported upon a collection of fig insects from several parts of the world, mainly collected by H. zu Solms-Laubach in the Botanical Gardens at Bogor (Java), and by F. M眉ller in Brazil. Gustav Mayr (1885) described and named the species listed by Mayer and some additional material sent by Solms from Bogor, thus providing a firm basis for the study of the fig wasps. In 1906, Mayr contributed an additional paper, consisting of corrections to his 1885 paper and descriptions of new species and genera. In the meantime Ashmead (1904) reviewed the classification of the Chalcid-oidea, and assigned the fig wasps to their proper place in this large group of Hymenoptera. From 1916 onwards, the knowledge of the fig wasps was greatly enlarged by Grandi, who published some fifty-five papers on their taxonomy, morphology,
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| [64] |
Fig wasps from Israeli Ficus sycomorus and related East African species (Hymenoptera, Chalcidoidea: Agaonidae) .
The study of many new samples of fig wasps collected in Africa by Dr. J. Galil of Tel-Aviv University, Israel, revealed the unexpected fact that Ceratosolen arabicus Mayr and C. galili Wiebes develop together in the same receptacles of Ficus sycomorus L. Dr. Galil made experiments on the host relations of these species and other inhabitants of the Sycomore receptacles, the results of which will be published by him. The identification of the Agaonidae and the Torymidae Sycophagini from Dr. Galil's catches, and some notes on their distribution, are given in the present paper. Unless otherwise indicated, all samples here recorded were reared from Ficus sycomorus L. (det. Galil). The insect material is preserved in the Rijksmuseum van Natuurlijke Historie (abbreviated RMNH in the text). Other abbreviations used are: BM (British Museum, Natural History), NMW (Naturhistorisches Museum, Wien), OUM (Oxford University Museum, Hope Department of Entomology), and USNM (United States National Museum). AGAONIDAE Ceratosolen arabicus Mayr and С. galili Wiebes (fig. 1) Material. — Ceratosolen arabicus Mayr: Eritrea, Ghinda, ex Ficus spec., leg. G. Rossetti, 1914, ex coll. Grandi, 2 ♀ 1 ♂ (RMNH 693; fragments ♀ slide 693b). Kenya, Isiolo, ix.1964 (Galil, no. 14), 3 ♀ 1 ♂ (RMNH 901); Lake Magadi, 20.X.1964 (Galil, no. 7), 9 ♀ 2 ♂ (RMNH 899; 3 ♀ slide 899a); Lake Magadi, 20.x.1964 (Galil, no. 8), 4 ♀ (RMNH 900) ; Kibwezi, 20.x.1964 (Galil, no. 44), 1 ♀ (RMNH 879); Mombasa, 16.11.1966 (Galil, no. 65B), 6 ♀ (RMNH 883). Tanganyika, Lake Manyara, 10.x.1964 (Galil, no. 32), 4 ♀ (RMNH 902) ; Usa, 11.x.1964 (Galil,
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| [65] |
The Indo-Australian Agaoninae (pollinators of figs) . Verhandelingen der Koninklijke Nederlandsche (Nederlandse) Akademie van Wetenschappen,
The Indo-Australian agaoninae (pollinators of figs) J. T. Wiebes （Verhandelingen der Koninklijke Nederlandse Akademie van Wetenschappen, Afd. Natuurkunde, Tweede reeks, d. 92） North-Holland, 1994
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Agaonidae (Hymenoptera Chalcidoidea) and Ficus (Moraceae): Fig wasps and their figs. VI. (Africa concluded) . |
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Ficus—A keystone plant species in the tropical rain forests ecosystem of south Yunnan .[本文引用: 1] 摘要 榕树──滇南热带雨林生态系统中的一类关键植物 .[本文引用: 1] 摘要 |
| [68] |
The incidence and pattern of copollinator diversification in dioecious and monoecious fig .https://doi.org/10.1111/evo.12584 URL PMID: 4328460 [本文引用: 2] 摘要
Differences in breeding system are associated with correlated ecological and morphological changes in plants. In Ficus, dioecy and monoecy are strongly associated with different suites of traits (tree height, population density, fruiting frequency, pollinator dispersal ecology). Although approximately 30% of fig species are pollinated by multiple species of fig-pollinating wasps, it has been suggested that copollinators are rare in dioecious figs. Here, we test whether there is a connection between the fig breeding system and copollinator incidence and diversification by conducting a meta-analysis of molecular data from pollinators of 119 fig species that includes new data from 15 Asian fig species. We find that the incidence of copollinators is not significantly different between monoecious and dioecious Ficus. Surprisingly, while all copollinators in dioecious figs are sister taxa, only 32.1% in monoecious figs are sister taxa. We present hypotheses to explain those patterns and discuss their consequences on the evolution of this mutualism.
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| [69] |
Sexual reproduction and stable coexistence of identical competitors .https://doi.org/10.1006/jtbi.1998.0712 URL PMID: 9735273 [本文引用: 1] 摘要
Abstract Current competition theory predicts that species must be ecologically distinct in order to stably coexist in the same community. This prediction is based on the implicit assumption that the consequences of sexual reproduction can be ignored. If anything, it is generally assumed that sex will only add problems, such as failure of insemination and inbreeding depression to species that have become rare, thus hastening competitive exclusion. Here we suggest that sexual reproduction may also bring rare species advantages in terms of the rate of per capita population growth. The key to our argument is that species-specific density dependence in population growth can occur when sexual reproduction is explicitly considered. We show that density-dependent sex ratio, sexual conflict, and sexually transmitted diseases can all promote species coexistence without separate niches.Copyright 1998 Academic Press
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Coexistence of cryptic species .https://doi.org/10.1111/ele.2004.7.issue-3 URL [本文引用: 1] |
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