生物多样性丧失已成为全球性危机(UNEP, 2021), 生物多样性的保护已受到全球范围的关注。第五版《全球生物多样性展望》指出, 即便世界各国为解决生物多样性快速丧失的问题做出了不懈努力, 但《2011‒2020年生物多样性战略计划》所提出的“爱知生物多样性目标” (“爱知目标”)仍然没有一项完全实现既定目标(SCBD, 2020), 实际结果甚至偏离目标(IPBES, 2019)。联合国《生物多样性公约》第十五次缔约方大会(COP15)于2022年12月19日就《昆明-蒙特利尔全球生物多样性框架》(《昆蒙框架》)达成一致, 框架确立了4个2050年生物多样性愿景的长期目标和23个2030年全球行动目标, 生物多样性保护任重道远, 是人类所面临的严峻挑战之一。中国作为COP15主席国, 为大会的顺利召开和达成共识发挥了重要作用, 并将在《昆蒙框架》目标实施和执行中发挥负责任大国的务实引领作用。以“生态文明: 共建地球生命共同体”为主题的COP15, 体现了国际社会对“生态文明”思想的认同, 对“地球生命共同体”理念的肯定。在COP15领导人峰会上, 我国宣布: “本着统筹就地保护与迁地保护相结合的原则, 启动北京、广州等国家植物园体系建设”, 着重强调了生物多样性迁地保护和就地保护相统一的原则, 将引领全球未来实现生物多样性保护理念和行动计划。
植物是生物多样性和生态系统的重要组成部分, 是人类社会和经济可持续发展不可或缺的基础和保障。由于人类活动和气候变迁及其造成的生境退化等因素的影响, 全球植物物种受威胁比例已超过40%, 并仍呈继续上升的趋势(Humphreys et al, 2019; Antonelli et al, 2020; Buchholz, 2023), 大量受威胁物种没有得到足够的保护, 或者在现有植物保护方法下其保护效果并不理想, 全球植物多样性保护现状不容乐观(Roberson et al, 2020; Huang et al, 2023)。植物多样性保护主要有就地保护(in situ conservation)和迁地保护(ex situ conservation)两种途径, 但这两种方法各有缺陷, 因此, 一些改进方案或新的植物保护策略相继提出(Husband & Campbell, 2004; Laguna et al, 2004; Volis & Blecher, 2010; 孙卫邦, 2013)。本文基于不同植物保护策略的原理和保护成效, 梳理了以迁地保护与就地保护为主的植物多样性保护途径存在的问题, 并结合作者近期的思考和研究实践, 提出统筹植物就地保护与迁地保护的并地保护(parallel situ conservation)策略。
1 就地保护与迁地保护存在的问题
由于人类活动的直接或间接影响, 物种赖以生存的自然生态系统遭到严重破坏, 致使全球大量物种受到非正常的灭绝威胁。据推测, 如不及时采取有效的保护措施, 到21世纪末, 将有2/3的高等维管植物消失(Pitman & Jorgensen, 2002)。因此, 珍稀濒危物种需要在人类的帮助下才能得到有效的保护, 就地保护和迁地保护是两种最主要的保护措施。
就地保护是指通过建立自然保护地等手段, 对原生境和自然生态系统进行保护, 从而维持和恢复物种在自然环境中可自然更新繁衍的种群(马建章等, 2012; 夏欣等, 2018)。就地保护作为植物保护的主流策略和方法, 仍然存在因人类活动或气候变迁带来的生境快速消失、生境片断化及生境恶化等问题。同时, 就地保护策略涉及地域面积广、监测难度大、对人力和财力的投入高等方面的限制(李俊生等, 2015)。而当物种的种群数量极少, 或者其原生境被严重破坏时, 在原生境以外的迁地保护为受威胁物种提供人为呵护就成为生物多样性保护的另一重要手段。因此, 就地保护和迁地保护相辅相成、互为补充, 成为当前拯救濒危物种的主要手段。与就地保护相比, 迁地保护便于集中管理, 其维护和监测成本更低, 但引种个体数量有限, 居群遗传多样性低, 保护物种的生存进化潜力存在不确定性。
就地保护是生物多样性保护中最直接的一项措施, 是拯救生物多样性的必要手段。截至2021年, 我国已建立474个国家级自然保护区(
植物迁地保护包括传统的植物园、种质资源圃、种子库和生物基因库等引种收集与保存活植物、种子、外植体和基因组样本的场所。种子库虽然能在尽量少破坏野生居群的情况下实现大量且长期的种子保存, 但该工作中提供种子的母株往往是有限且缺乏遗传多样性的(Schoen & Brown, 2001), 对于种子萌发率低、顽拗型(recalcitrant)种子或不休眠的种子则只能进行活植物收集和保育(Volis, 2017)。活植物收集是植物园的核心和“灵魂”, 植物园作为植物迁地保护的专业机构, 在保护植物多样性方面发挥着越来越大的作用(黄宏文等, 2015)。但植物园有限的空间和数量庞大的物种引种栽培, 通常只是解决了植物α多样性的保存, 植物园迁地保护的植物通常具有极小居群特征, 即由少数建群个体构成的种群, 在人工栽培条件下, 居群大小变化剧烈、遗传多样性及适应性进化潜力丧失严重。遗传多样性是生物适应环境变化能力的保障, 保护遗传多样性即是保护生物进化的潜力(康明等, 2005), 因此, 如何解决缺乏遗传代表性或完整性等遗传风险是以植物园活植物收集为代表的植物迁地保护的核心问题(黄宏文和廖景平, 2022)。
2 植物迁地保护的居群遗传风险
2.1 遗传多样性丧失
遗传多样性涵盖了同一物种不同居群和个体间所有遗传上的差异, 它是物种生存与进化的遗传物质基础。由于珍稀濒危植物多为小居群, 个体数量稀少, 这在客观上造成植物园在收集、引种时的困难。因此, 一个普遍的现象是: 在植物园迁地保存的植物中, 栽培的个体通常只有少数几棵植株, 甚至一部分来自植物园之间的重复引种, 这就使得植物园目前保存的绝大部分珍稀濒危植物不能涵盖物种足够的遗传多样性, 即缺乏遗传代表性。从群体遗传学的角度看, 在迁地保护中预设的目标是: 至少在100年内保持物种90%以上的遗传多样性。因此, 涵盖物种的遗传多样性是迁地保护的核心, 是衡量迁地保护策略有效性的前提和关键指标。
朱红艳等(2005)评估了武汉植物园引种的5株伞花木(Eurycorymbus cavaleriei)及其200多株子代幼苗的遗传多样性, 发现其群体的遗传多样性低于10%, 表明该物种的迁地保护居群的遗传多样性极低。实际上, 伞花木是一个广布物种, 该物种本身的遗传多样性并不低。显然, 迁地保护居群遗传多样性低源于迁地居群来自同一亲本或亲缘关系极近的少数个体。在中国科学院西双版纳热带植物园迁地保护的广西青梅(Vatica guangxiensis)的情况则不同, Li等(2002)将植物园迁地居群与3个自然居群进行遗传多样性比较, 发现迁地居群涵盖的遗传多样性达到了自然居群的88.3%, 说明对广西青梅的迁地保护在遗传多样性水平上基本是成功的, 虽然仍然有一些自然居群中的特有等位基因没有被取样。实际上, 多年生或长寿的种子植物往往可以生存百年甚至数百年, 即便是小居群, 其遗传多样性的丧失也会比较慢, 合理的取样策略和适当的管理方法可以维持其足够的遗传多样性。
2.2 近交与杂交
近交会降低居群中杂合个体的数量, 从而使隐性有害基因在子代中表达, 从短期来看, 隐性有害基因的表达带来的子代健康度下降是近交衰退的直接表现, 而因子代死亡率增加导致部分基因型的丧失从而降低遗传多样性, 则是一个长期遗传效应。Newman和Pilson (1997)对克拉花(Clarkia pulchella)小居群(N = 12)不同近交程度的灭绝速率进行研究发现, 到第3代, 高度近交居群的灭绝速率是轻度近交群体的3.6倍。在植物园的迁地保护工作中, 因植物园的空间局限性, 保存每个物种的个体数量有限, 因此, 近交和近交衰退通常不可避免。同时, 迁地保护管理过程中, 如果缺乏谱系记录, 导致同一家系反复近亲繁殖, 则更增加了近交衰退的风险。植物迁地保护要降低近交衰退, 详细的引种记录和谱系遗传管理至关重要。通过模拟自然状况的花粉流格局, 有目的地人工授粉, 促进植株间个体远交并最大化授粉父本植株的数量, 是植物园迁地居群遗传管理的有效方法之一。
对于珍稀濒危物种来说, 杂交产生的遗传风险有杂交衰退(outbreeding depression)、遗传同化(genetic assimilation)和基因渐渗(introgression)等导致的小种群灭绝(Seehausen, 2004; Todesco et al, 2016)。研究表明, 在美国加利福尼亚州, 野生胡桃属稀有物种黑核桃(Juglans hindsii)因被栽培种核桃(J. regia)杂交而面临灭绝的风险(Ellstrand & Elam, 1993)。加利福尼亚州分布的一种原生灯芯草(Spartina foliosa)在互花米草(S. alterniflora)入侵后与之发生杂交, 导致加利福尼亚当地的灯芯草已经濒临灭绝(Ayres et al, 1999, 2004; Strong & Ayres, 2013)。值得注意的是, 该案例中的原生灯芯草并不是濒危物种, 这说明杂交对物种灭绝的威胁不仅仅局限于濒危物种。
2.3 遗传适应
迁地保护的植物居群, 因迁地栽培环境与其原生境之间的差异, 在迁地保护下繁衍的过程中不可避免地被附加了人为选择压力, 使迁地栽培植物发生遗传适应性改变(Husband & Campbell, 2004), 迁地环境下繁衍的后代无法适应其自然的原生环境, 从而不能实现其野外回归的目的(Enßlin et al, 2015)。珍稀濒危植物在植物园迁地保护的过程中, 由于生境的变化和栽培下有意识或无意识的人工选择, 植物在表型、抗性和生活史等方面发生可以遗传的变化是必然的, 这种变化给后续物种的野外回归带来了不利影响。黄仕训等(2001)发现, 将7种稀有植物从富钙的石灰岩地区引种到植物园的酸性土壤中后, 在形态和生活史等方面发生了不同程度的变化。因此, 在濒危物种的原产地就近进行迁地保护, 避免人为的选择, 其目的之一就是尽可能地减少濒危物种在迁地保护条件下的遗传适应改变。Schröder和Prasse (2013)发现人工栽培的植物种子相较于野生来源的种子萌发早且萌发率更高。这类案例虽不能直接证明迁地保护的居群发生遗传适应后对野外环境的健康度有多大程度的影响, 但足以证明植物在迁地保护过程中其遗传适应性的变化。
3 濒危植物保护的居群遗传风险应对策略
由植物迁地保护居群的遗传风险不难看出, 迁地保护居群更易偏离原始居群的遗传本底发生遗传漂变(genetic drift), 且在栽培管理过程中存在近交衰退、种间杂交、遗传污染和病虫害等一系列风险。迁地保护的植物通常是小居群, 与小居群相关的居群遗传学问题是迁地保育居群的现实问题。为提高迁地保护效率, 增加野外回归实现的成功概率, 从迁地保护植物管理方面已提出了许多对应的策略(黄宏文, 2018)。
3.1 迁地保护居群的管理策略
保育基因组学(conservation genomics)时代, 高通量测序技术的发展降低了获取分子标记及其基因型的成本, 为非模式生物基因组水平的遗传多样性研究带来了新的契机(Avise, 2010; Ekblom & Galindo, 2011)。了解濒危植物野生居群遗传多样性水平对于制定有效的取样策略是非常必要的。Yi等(2022)对报春苣苔(Primulina tabacum)的17个野生居群进行全基因组进化研究, 根据其交配系统的特点, 将其分成完全自交、完全异交和混交3种类型。我们利用其已经公布的群体重测序数据(Yi et al, 2022), 对不同交配系统的报春苣苔居群遗传多样性进行了比较, 发现自交居群内的遗传多样性位点仅占多态性位点总数的27.7%, 而报春苣苔超过60%的遗传多样性可以在任何一个异交群体中被找到。对于濒危物种来说, 如果只从其中某一个居群取样, 其大部分遗传多样性将被遗漏。从报春苣苔的案例中可以看出, 自交植物的遗传多样性主要分布在居群间, 而异交植物的遗传多样性则主要包含在居群内。在实际工作中, 大规模地进行遗传多样性调查还存在一定困难, 实践中可以根据物种的分布、物候、生活史或繁育系统特征等来初步判断其遗传多样性的分布趋势。许再富(1998)总结多年的实践经验, 认为应根据不同的生活史、生态型和繁育系统等特征, 针对性地制定不同的取样策略, 同时, 他认为对大多数物种来说, 每种应至少有10-20株在5个植物园得到迁地保护。
在防止迁地保护居群的近交衰退中, 除了注意谱系来源问题外, 植物园间的种质交换也可发挥一定作用。此外, 因为植物园空间和容量的局限性, 与其长期保存少数几个个体, 不如有计划地逐步开展回归引种。珍稀濒危植物在植物园内与近缘种发生种间杂交是必然的, 迁地种群的遗传混杂或遗传污染是迁地保护管理需高度重视的问题之一。Zhang等(2010)通过授粉控制实验发现, 迁地保护在武汉植物园的珍稀濒危物种秤锤树(Sinojackia xylocapa)和狭果秤锤树(S. rehderiana)产生种间杂交, 表明对保护物种的迁地保存通过栽培设计而形成有效隔离是植物园迁地保护的重要工作。这种杂交同样可能发生在物种内, 同一物种处于不同生境条件下的居群会演化成不同的生态型, 杂交可能会导致地方适应性(local adaptation)的性状和基因型丢失。
当迁地保护居群脱离原生境而被迫在植物园等保存区进行繁衍时, 遗传适应则不可避免。为尽可能地减少濒危物种在迁地保护条件下的遗传适应, IUCN建议在濒危物种的原产地就近进行迁地保护, 并且避免人为的选择(
3.2 其他植物保护策略
许再富等(2009)统计了中国的植物园中迁地保护植物的生长和适应性, 发现植物迁地保护的有效性较差, 并且认为造成这种结果的重要原因之一是植物的生态适应局限性和植物迁地保护的生态环境与植物原产地的差异较大所致(许再富等, 2012)。为解决植物迁地保护的气候和环境与原生境差异较大的问题, 云南省林业厅曾于2005年提出“近地保护” (near situ conservation)的概念, 即在物种现有分布区(点)范围内的附近, 选择与其相同气候和相似的生境建立人工保护点(孙卫邦, 2013)。许再富等(2012)以38种国家重点保护野生植物为研究对象, 对它们的“迁地”与“近地”保护有效性进行了比较研究, 结果发现近地保护的38种珍稀濒危植物中, 适应性良好的占总数的92%, 且近地保护植株的生长适应性和年均生长量远远高于迁地保护的植株。该方法最大的优势在于, 利用自然生境改善被保护居群的生长和繁殖条件, 但仍然缺乏对居群遗传多样性丧失问题的考虑。同时, 近地保护主要是针对分布点极其有限的小种群濒危植物而提出, 且这些物种濒危大都是由人类经济活动破坏其生境, 或因自身繁殖系统存在缺陷等造成的。对于其他珍稀濒危但并非小种群的物种目前还缺乏研究。Volis和Blecher (2010)提出的“拟就地保护” (quasi in situ conservation)与近地保护非常相似, 强调在迁地保护时选择与原生境相似的自然或半自然地段建立人工种群, 并采集以种子为主的繁殖材料进行回归引种。
Laguna等(2004)在就地保护的基础上提出了“微保护区” (micro-reserves)的方法, 微保护区由若干小于20 ha的片断化的小型保护地组成网络, 该方法最大的优点是可以避免地权纠纷, 在不建立大面积的自然保护区的情况下, 快速开展以就地保护为主的植物抢救性保护。值得注意的是, “微保护区”的成功需以不同保护地单元间的基因交流为前提, 因为对濒危植物来说, 栖息地的连通性(connectivity)是其生存和繁衍的重要保障(Yesuf et al, 2021), 边缘效应(edge effects)和片断化是该方法存在的两个居群遗传学问题。Husband和Campbell (2004)提出了“间地保护” (inter situ conservation)的概念, 但缺乏详细的方案和实施策略。此后, Burney和Burney (2007)对这个概念进行拓展, 并给出了可行的方案, 即将受保护居群进行野外回归时, 选择的回归地为当前已无该物种分布但属于近期历史栖息地, 通过人为管理实现种群的恢复。但Volis和Blecher (2010)认为该方案存在一个致命缺陷, 即该方案实际上是将野外回归地变成了另一个迁地保护区域, 没能解决迁地保护的遗传多样性缺失的问题。Uma Shaanker及其团队提出了“森林基因库” (forest gene banks)的保护方法, 该方法以一个居群的就地保护为基础, 向该保护区引入其他居群的个体, 以此形成一个基因库(Uma Shaanker & Ganeshaiah 1997; Uma Shaanker et al, 2001, 2002)。该方法对森林树种的种质资源保护是一个有效策略, 但应用范围有限。
从以上植物保护策略的概念和方法探讨中不难发现, 均在寻求就地保护和迁地保护的中间状态或衔接途径, 即寻求统筹就地保护与迁地保护的新策略和新方法, 但都不尽如人意, 尤其是忽略了对迁地植物种群遗传多样性和适应进化潜力的有效保护。
4 并地保护的原理与方法
4.1 植物迁地保护与基因流
遗传多样性是评估一个物种或居群灭绝风险或濒危等级的重要指标, 即高水平的遗传多样性确保居群有足够的遗传潜力适应快速变化的环境, 而当居群遗传多样性低时, 往往会出现自交衰退或健康度下降等现象而使居群受到生存威胁(Spielman et al, 2004; Markert et al, 2010), 换言之, 物种的濒危或灭绝本质上是遗传多样性的丧失。植物迁地保护不可避免地缺乏物种的遗传代表性, 也难免出现遗传漂变、遗传瓶颈、自交衰退等居群遗传问题。针对如何解决受保护居群与野生居群之间的基因交流问题, 曾提出过不少管理对策, 比如定期从野外居群引入个体等。然而, 目前没有关于迁地保护居群与野生居群或就地保护居群之间的基因交流的案例报道。
有花植物除自交植物外, 均通过风、鸟、昆虫等进行传粉(Culley et al, 2002)。在肯尼亚进行的豇豆(Vigna unguiculata)作物与野生居群之间的传粉研究中, Pasquet等(2008)调查了大木蜂(Xylocopa flavorufa)在豇豆不同居群间对基因流的贡献, 结果发现蜜蜂具有长距离传播花粉的能力, 其最远传播距离可达6 km。相对于蜜蜂等昆虫, 鸟类和蝙蝠能将花粉传播到更远的距离(Krauss et al, 2017; Wessinger, 2021)。风媒传粉是一种重要的传粉方式，风媒传粉植物种数大约为动物传粉植物的1/10 (Ollerton et al, 2011)。Rogers和Levetin (1998)在对美国南部的北美沙地柏(Juniperus ashei)进行花粉远距离传播(风媒传播)的研究中发现, 其花粉能从德克萨斯州的中部传播到俄克拉荷马州的南部, 其直线距离远达200 km。但该研究既没有探索其远距离传播的花粉是否有活力, 也没有验证居群是否通过远距离传播的花粉发生了杂交。
为了探索通过风媒远距离传播的花粉对促进基因交流的作用, 近期, 我们在江西省庐山国家级自然保护区内, 对风媒传粉在小叶青冈(Quercus myrsinifolia)不同居群间花粉流中的贡献进行了调查。根据小叶青冈在庐山上的分布, 对3个居群进行了样品采集(图1), 对各居群的幼苗进行父系检测, 研究结果表明3个居群相互之间都能因为花粉的传播而产生杂交后代(图2), 从西南向东北方向(从S居群到N居群、从C居群到N居群)花粉传播产生的杂交比例比从东北往西南方向产生的杂交比例高, 这可能是由于小叶青冈开花时间(6月前后)的风向所致; 而S居群与C居群之间虽然水平距离相近, 但杂交率比较低, 可能是因为海拔变化及山体地形阻隔不利于花粉的传播所致。该研究证明了远距离传播的花粉能促进小叶青冈居群间的基因交流。
图1
图1
江西省庐山国家级自然保护区的小叶青冈取样分布图。数字表示各居群间的平均水平距离。N: 北部居群; C: 中部居群; S: 南部居群。
Fig. 1
Geographic information of Quercus myrsinifolia sampling in Mount Lushan National Nature Reserve. Horizontal distances among populations are labeled between each population pairs. N, North population; C, Central population; S, South population.
图2
图2
江西省庐山国家级自然保护区不同小叶青冈居群间的杂交率。箭头表示花粉传播方向, 数字表示该花粉传播方向造成的杂交率。
Fig. 2
Rate of hybridization among different Quercus myrsinifolia populations in Mount Lushan National Nature Reserve. Arrows and numbers indicate the pollen dispersal and hybridization rates.
4.2 并地保护方法
从上述综述结果可以看出, 现行的植物保护策略和方法均存在缺陷, 尤其是植物迁地保护中存在的遗传风险, 比如遗传多样性丧失、近交或远交衰退、遗传适应等, 近年来相继提出的近地保护和间地保护等改良方法都没有从根本上解决这些问题, 或者至少不是从解决遗传风险的角度出发提出的改良方法。根据居群遗传学原理(黄宏文, 2018)和前文花粉流研究的案例可知, 当迁地保护居群与自然居群或就地保护居群之间发生基因交流时, 可有效地解决迁地保护居群的遗传风险问题, 从而保护物种的遗传多样性和适应性进化潜能。在此, 我们从居群间基因流动态连接就地居群与迁地保护居群的思路, 提出并地保护(对照)新方法, 以统筹就地保护和迁地保护为着力点, 完善现有植物迁地保护存在的弊端, 解决植物迁地保护遗传多样性丧失导致的物种适应性进化潜能等问题。
并地保护是通过构建迁地保护居群与就地保护或自然居群之间的基因流以达到保护植物进化潜能的植物保护方式, 其概念主要是根据植物居群间基因流动态规律进行保护物种的迁地保育设计(图3), 其核心是通过居群间花粉或种子传播的基因流连接自然居群与迁地保护居群。因此, 在自然保护区等就地保护区域内或周边花粉或种子可传播范围内, 建立植物迁地保育圃, 使迁地保护居群与就地自然居群之间维持基因交流, 即: 将迁地保护小居群融入自然大居群的基因池并有效维持物种的适应性进化潜能。该方法对珍稀濒危植物尤其重要, 可有效避免植物园迁地小居群的遗传退化和对栽培环境的人为选择产生的健康度和野外适应性降低。并地保护策略在方法上要求就地自然居群和迁地保护居群基因流连接, 从前文对传粉媒介与基因流的调查和研究不难看出, 并地保护适用于风媒和虫媒传粉植物, 其主要限制在于基因流的距离, 即花粉和种子的传播距离。因此, 深入的“一种一策”的花粉流或种子流检测和保育圃设计是该方法成功的关键。
图3
并地保护仍以迁地保护为基础。同时, 并地保护因引入了就地保护居群或自然居群的基因流, 从而增强了对居群遗传多样性和适应性进化潜能的保护。与近地保护不同, 并地保护并非仅以实现个体与居群正常生长为主要目的, 而是通过连通迁地保护居群与自然居群间的基因流, 维系迁地保护居群的遗传多样性和适应性进化潜力。通过对现有植物保护策略和方法的梳理(表1)可知, 不同植物保护策略和方法各有特色, 它们在实现生物多样性保护的工作中相辅相成、互为补充。并地保护也将发挥其不可替代的重要作用, 即便对于野外栖息地已几近丧失或已野外灭绝的物种, 虽然迁地保护可能是其唯一可选的保护途径, 但在实现自然生境归化种植的初期, 并地保护仍是十分必要的。
表1 野生濒危植物保护策略和方法的比较
Table 1
| 保护策略 Conservation strategy | 保护对象 Conservation target | 保护单元 Conservation unit | 方法和依据 Method and justification | 多样性保护 Diversity conservation | 存在的主要问题 Main limitations |
|---|---|---|---|---|---|
| 就地保护 In situ conservation | 生态系统 Ecosystem | 群落 Community | 原生态自然过程 Natural process | α、β、γ多样性 α, β, γ diversity | 生境消失, 气候变迁 Habitat loss, climate changes |
| 迁地保护 Ex situ conservation | 珍稀濒危类群 Rare and endangered plants | 个体或小居群 Individuals or small population | 自然栖息地以外管护 Outside habitats and controlled care | α多样性 α diversity | 遗传多样性丧失 Genetic diversity loss |
| 近地保护 Near situ conservation | 珍稀濒危类群 Rare and endangered | 个体或小居群 Individuals or small population | 相似的气候与环境 Similar climate and environment | α多样性 α diversity | 遗传多样性丧失, 外在风险脆弱性 Genetic diversity loss, vulnerability to local threats |
| 微保护区 Micro-reserves | 片断化生态系统 Fragmented ecosystem | 群落 Community | 城市生态系统 Urban ecosystem | α和β多样性 α, β diversity | 边缘效应, 片断化 Edge effects, fragmentation |
| 间地保护 Inter situ conservation | 珍稀濒危类群 Rare and endangered plants | 个体或小居群 Individuals or small population | 临时措施至新栖息地 Temporary measures until new habitats found | α多样性 α diversity | 遗传多样性丧失 Genetic diversity loss |
| 森林基因库 Forest gene bank | 森林树种种质 Germplasm of forest trees | 遗传材料 Genetic materials | 天然种子库 Natural seed banks | 遗传多样性 Genetic diversity | 遗传代表性不足 Limited genetic representation |
| 并地保护 Parallel situ conservation | 珍稀濒危类群 Rare and endangered plants | 居群或物种 Population or species | 基因流及居群遗传学原理 Gene flow and population genetics | α和β多样性 α, β diversity | 受环境和自然居群因素限制 Restricted by environment and natural populations availability |
5 总结和展望
即便联合国等国际组织多次制定计划并设定目标, 全球植物多样性危机依旧存在, 植物濒危的数量和速度甚至有增无减, 而通过人为努力成功保护下来的珍稀濒危植物屈指可数。本文系统地梳理了现行植物保护策略和方法的优缺点, 为实现物种遗传多样性及遗传进化潜力的有效保护, 现有植物保护策略仍需进行改良和提升。同时, 以应对气候变迁等不确定因素和解决居群遗传风险为目的的新的植物保护策略仍然任重道远。本文依据居群遗传学原理和多年实践, 从居群间基因流动态连接就地居群与迁地保护居群的思路, 提出了并地保护的新方法。该方法在设计原理上依据居群遗传学, 以实现保护遗传进化潜力的目的, 以珍稀濒危植物类群为保护对象, 是对现有植物保护策略的一个有益补充。
然而, 不可否认的是, 并地保护策略的提出是基于对前人研究的思考, 和作者近期对其实现途径初步研究结果的推断, 其应用效果还需基于“一种一策”的原则对迁地保育圃与自然居群的遗传多样性和基因交流进行系统的评估和检验。该方法对植物保护的成功与否是基于基因流的动态连接, 在野生居群几近灭绝的情况下, 基因流自然消失, 因此, 并地保护并不能取代迁地保护, 而只适用于存在一定规模的野生居群的情况, 或者适用于迁地保护植物进行野外回归的初期。植物就地保护和迁地保护各有其优缺点。近年来, 中国相继启动国家公园和国家植物园体系建设, 为植物就地保护与迁地保护的有机结合提供了契机, 基于此, 提出和实践植物并地保护策略, 是统筹植物就地保护与迁地保护的重要建议和措施。
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DOI:10.3724/SP.J.1259.2015.00280
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近500年来, 植物引种驯化及其广泛栽培深刻改变了世界农业生产的格局, 对促进人类社会文明进步产生了深远的影响。无论在西方殖民地发展史还是在我国明清发展史中, 每一种重要栽培植物的成功引种和驯化, 都对历史进程产生了不可估量的作用。活植物收集是植物园的核心和“灵魂”, 传承了现代植物园几个世纪科学研究的脉络和成就。活植物收集是植物园科学研究的基础和支撑平台, 也是当前和未来发展的根本。基于活植物收集的植物园研究工作具有多学科综合的特征, 既对基础生物学研究具有重要意义, 也与经济繁荣、社会发展和人类日常生活密切相关。
On China’s national botanical gardens: Building a comprehensive system of ex situ conservation of national botanical gardens with task oriented disciplines
DOI:10.17520/biods.2022220 URL [本文引用: 1]
论我国国家植物园体系建设: 以任务带学科构建国家植物园迁地保护综合体系
DOI:10.17520/biods.2022220
[本文引用: 1]
植物园诞生的原初是“皇家”或“国家”意志的产物, 植物园的概念从公元前2,800年我国的“神农本草园”起源, 至今已历经沧桑巨变, 而西方文艺复兴后演替出了现代植物园。科研、保护、教育与示范四大功能始终是植物园的主线。植物园作为专门从事野生植物收集、科学研究、引种驯化和保护利用的专业研究机构, 始终肩负着国家的重要使命。本文系统综述了植物园的起源与演变, 并对世界各国的国家植物园与国家植物园体系进行了系统梳理和分析。在对我国植物园历史与发展概况总结的基础上, 论述了我国国家植物园体系建设的定位与目标、区域布局、科学研究、人才队伍、基础设施等五个方面的思考, 以任务带学科构建我国国家植物园迁地保护综合体系。
China: The role of botanical gardens in conservation
DOI:10.1016/j.xinn.2023.100433 URL [本文引用: 3]
Variation in characteristics of rare and threatened plants after ex-situ conservation
DOI:10.17520/biods.2001053 URL [本文引用: 1]
石山稀有濒危植物在迁地保护后的性状变异
Global dataset shows geography and life form predict modern plant extinction and rediscovery
Conservation genetics and the role of botanical gardens
Population responses to novel environments:Implications for ex situ plant conservation
Global Assessment Report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services
Genetic risks in plant ex situ conservation
植物迁地保护中的遗传风险
Novel consequences of bird pollination for plant mating
DOI:S1360-1385(17)30045-6
PMID:28412035
[本文引用: 1]
Pollinator behaviour has profound effects on plant mating. Pollinators are predicted to minimise energetic costs during foraging bouts by moving between nearby flowers. However, a review of plant mating system studies reveals a mismatch between behavioural predictions and pollen-mediated gene dispersal in bird-pollinated plants. Paternal diversity of these plants is twice that of plants pollinated solely by insects. Comparison with the behaviour of other pollinator groups suggests that birds promote pollen dispersal through a combination of high mobility, limited grooming, and intra- and interspecies aggression. Future opportunities to test these predictions include seed paternity assignment following pollinator exclusion experiments, single pollen grain genotyping, new tracking technologies for small pollinators, and motion-triggered cameras and ethological experimentation for quantifying pollinator behaviour.Copyright © 2017 Elsevier Ltd. All rights reserved.
The role of small reserves in plant conservation in a region of high diversity in eastern Spain
DOI:10.1016/j.biocon.2004.01.001 URL [本文引用: 2]
Ten ecosystem approaches to the planning and management of the Great Lakes
DOI:10.1016/S0380-1330(82)71989-6 URL [本文引用: 1]
Ex situ genetic conservation of endangered Vatica guangxiensis (Dipterocarpaceae) in China
DOI:10.1016/S0006-3207(01)00240-3 URL [本文引用: 1]
Research and practice on biodiversity in situ conservation in China: Progress and prospect
DOI:10.3724/SP.J.1003.2012.08118 URL [本文引用: 2]
中国生物多样性就地保护的研究与实践
DOI:10.3724/SP.J.1003.2012.08118
[本文引用: 2]
中国是世界上生物多样性最丰富的地区之一, 但面临着较大的生态衰退风险。中国生物多样性受到的威胁来自包括人口众多、经济发展模式单一落后、工业化进程加快、气候变化和外来物种入侵等多种因素。生物多样性的就地保护对于维护国家生态安全具有重要意义, 同时也是中国可持续发展的需要。本文就中国生物多样性就地保护的研究成果和保护成就进行了回顾, 提出了未来应该着重加强的研究领域。中国生物多样性的就地保护研究与实践主要集中在生物多样性资源调查、濒危物种管理和自然保护区建设等方面。中国政府在生物多样性就地保护领域开展了大量卓有成效的工作, 发布实施了一系列的保护行动规划, 不断提高了生物多样性的保护水平。中国的生物多样性就地保护经过了由数量发展到质量发展的阶段后, 未来的研究重点应该集中在生物多样性形成与维持机制、生物多样性受胁原因与响应机制、生物多样性长期监测与评估、自然保护区有效管理和自然保护区立法等方面。
Population genetic diversity and fitness in multiple environments
DOI:10.1186/1471-2148-10-205
PMID:20609254
[本文引用: 1]
Background: When a large number of alleles are lost from a population, increases in individual homozygosity may reduce individual fitness through inbreeding depression. Modest losses of allelic diversity may also negatively impact long-term population viability by reducing the capacity of populations to adapt to altered environments. However, it is not clear how much genetic diversity within populations may be lost before populations are put at significant risk. Development of tools to evaluate this relationship would be a valuable contribution to conservation biology. To address these issues, we have created an experimental system that uses laboratory populations of an estuarine crustacean, Americamysis bahia with experimentally manipulated levels of genetic diversity. We created replicate cultures with five distinct levels of genetic diversity and monitored them for 16 weeks in both permissive (ambient seawater) and stressful conditions (diluted seawater). The relationship between molecular genetic diversity at presumptive neutral loci and population vulnerability was assessed by AFLP analysis. Results: Populations with very low genetic diversity demonstrated reduced fitness relative to high diversity populations even under permissive conditions. Population performance decreased in the stressful environment for all levels of genetic diversity relative to performance in the permissive environment. Twenty percent of the lowest diversity populations went extinct before the end of the study in permissive conditions, whereas 73% of the low diversity lines went extinct in the stressful environment. All high genetic diversity populations persisted for the duration of the study, although population sizes and reproduction were reduced under stressful environmental conditions. Levels of fitness varied more among replicate low diversity populations than among replicate populations with high genetic diversity. There was a significant correlation between AFLP diversity and population fitness overall; however, AFLP markers performed poorly at detecting modest but consequential losses of genetic diversity. High diversity lines in the stressful environment showed some evidence of relative improvement as the experiment progressed while the low diversity lines did not. Conclusions: The combined effects of reduced average fitness and increased variability contributed to increased extinction rates for very low diversity populations. More modest losses of genetic diversity resulted in measurable decreases in population fitness; AFLP markers did not always detect these losses. However when AFLP markers indicated lost genetic diversity, these losses were associated with reduced population fitness.
Increased probability of extinction due to decreased genetic effective population size: Experimental population of Clarkia pulchella
DOI:10.1111/j.1558-5646.1997.tb02422.x
PMID:28565367
[本文引用: 1]
We established replicated experimental populations of the annual plant Clarkia pulchella to evaluate the existence of a causal relationship between loss of genetic variation and population survival probability. Two treatments differing in the relatedness of the founders, and thus in the genetic effective population size (N ), were maintained as isolated populations in a natural environment. After three generations, the low N treatment had significantly lower germination and survival rates than did the high N treatment. These lower germination and survival rates led to decreased mean fitness in the low N populations: estimated mean fitness in the low N populations was only 21% of the estimated mean fitness in the high N populations. This inbreeding depression led to a reduction in population survival: at the conclusion of the experiment, 75% of the high N populations were still extant, whereas only 31% of the low N populations had survived. Decreased genetic effective population size, which leads to both inbreeding and the loss of alleles by genetic drift, increased the probability of population extinction over that expected from demographic and environmental stochasticity alone. This demonstrates that the genetic effective population size can strongly affect the probability of population persistence.© 1997 The Society for the Study of Evolution.
How many flowering plants are pollinated by animals
DOI:10.1111/more.2010.120.issue-3 URL [本文引用: 1]
Long-distance pollen flow assessment through evaluation of pollinator foraging range suggests transgene escape distances
Estimating the size of the world’s threatened flora
Fund plant conservation to solve biodiversity crisis
Evidence of long-distance transport of mountain cedar pollen into Tulsa, Oklahoma
DOI:10.1007/s004840050086 URL [本文引用: 1]
The conservation of wild plant species in seed banks
DOI:10.1641/0006-3568(2001)051[0960:TCOWPS]2.0.CO;2 URL [本文引用: 1]
Cultivation and hybridization alter the germination behavior of native plants used in revegetation and restoration
DOI:10.1111/rec.2013.21.issue-1 URL [本文引用: 1]
Global Biodiversity Outlook 5
Hybridization and adaptive radiation
DOI:10.1016/j.tree.2004.01.003 URL [本文引用: 1]
The Ecosystem Approach: Five Steps to Implementation
Most species are not driven to extinction before genetic factors impact them
Ecological and evolutionary misadventures of Spartina
DOI:10.1146/ecolsys.2013.44.issue-1 URL [本文引用: 1]
Hybridization and extinction
DOI:10.1111/eva.12367
PMID:27468307
[本文引用: 1]
Hybridization may drive rare taxa to extinction through genetic swamping, where the rare form is replaced by hybrids, or by demographic swamping, where population growth rates are reduced due to the wasteful production of maladaptive hybrids. Conversely, hybridization may rescue the viability of small, inbred populations. Understanding the factors that contribute to destructive versus constructive outcomes of hybridization is key to managing conservation concerns. Here, we survey the literature for studies of hybridization and extinction to identify the ecological, evolutionary, and genetic factors that critically affect extinction risk through hybridization. We find that while extinction risk is highly situation dependent, genetic swamping is much more frequent than demographic swamping. In addition, human involvement is associated with increased risk and high reproductive isolation with reduced risk. Although climate change is predicted to increase the risk of hybridization-induced extinction, we find little empirical support for this prediction. Similarly, theoretical and experimental studies imply that genetic rescue through hybridization may be equally or more probable than demographic swamping, but our literature survey failed to support this claim. We conclude that halting the introduction of hybridization-prone exotics and restoring mature and diverse habitats that are resistant to hybrid establishment should be management priorities.
Mapping genetic diversity of Phyllanthus emblica: Forest gene banks as a new approach for in situ conservation of genetic resources
A new approach to conservation of genetic resources of forest trees:Promise and processes
Forest gene banks—A new integrated approach for the conservation of forest tree genetic resources
Making Peace with Nature: A Scientific Blueprint to Tackle the Climate, Biodiversity and Pollution Emergencies
Complementarities of two existing intermediate conservation approaches
Quasi in situ: A bridge between ex situ and in situ conservation of plants
DOI:10.1007/s10531-010-9849-2 URL [本文引用: 3]
Protected areas may not effectively support conservation of endangered forest plants under climate change
DOI:10.1007/s12665-016-5364-4 URL [本文引用: 1]
From pollen dispersal to plant diversification: Genetic consequences of pollination mode
DOI:10.1111/nph.17073
PMID:33159813
[本文引用: 1]
Pollinators influence patterns of plant speciation, and one intuitive hypothesis is that pollinators affect rates of plant diversification through their effects on pollen dispersal. By specifying mating events and pollen flow across the landscape, distinct types of pollinators may cause different opportunities for allopatric speciation. This pollen dispersal-dependent speciation hypothesis predicts that pollination mode has effects on the spatial context of mating events that scale up to impact population structure and rates of species formation. Here I consider recent comparative studies, including genetic analyses of plant mating events, population structure and comparative phylogenetic analyses, to examine evidence for this model. These studies suggest that highly mobile pollinators conduct greater gene flow within and among populations, compared to less mobile pollinators. These differences influence patterns of population structure across the landscape. However, the effects of pollination mode on speciation rates is less predictable. In some contexts, the predicted effects of pollen dispersal are outweighed by other factors that govern speciation rates. A multiscale approach to examine effects of pollination mode on plant mating system, population structure and rates of diversification is key to determining the role of pollen dispersal on plant speciation for model clades.© 2020 The Authors New Phytologist © 2020 New Phytologist Foundation.
Impact of past and future climate change on the potential distribution of an endangered montane shrub Lonicera oblata and its conservation implications
DOI:10.3390/f12020125
URL
[本文引用: 1]
Climate change is an important driver of biodiversity patterns and species distributions, understanding how organisms respond to climate change will shed light on the conservation of endangered species. In this study, we modeled the distributional dynamics of a critically endangered montane shrub Lonicera oblata in response to climate change under different periods by building a comprehensive habitat suitability model considering the effects of soil and vegetation conditions. Our results indicated that the current suitable habitats for L. oblata are located scarcely in North China. Historical modeling indicated that L. oblata achieved its maximum potential distribution in the last interglacial period which covered southwest China, while its distribution area decreased for almost 50% during the last glacial maximum. It further contracted during the middle Holocene to a distribution resembling the current pattern. Future modeling showed that the suitable habitats of L. oblata contracted dramatically, and populations were fragmentedly distributed in these areas. As a whole, the distribution of L. oblata showed significant migration northward in latitude but no altitudinal shift. Several mountains in North China may provide future stable climatic areas for L. oblata, particularly, the intersections between the Taihang and Yan mountains. Our study strongly suggested that the endangered montane shrub L. oblata are sensitive to climate change, and the results provide new insights into the conservation of it and other endangered species.
Evaluation of in-situ conservation of mammals in China
我国哺乳动物就地保护状况评估
Comparative study on conservative efficiency of national protected plants between “Off Site” and “Near Site” Conservation
国家重点保护植物“迁地”与“近地”保护有效性的比较研究
A commentary on plant ex situ conservation and its researches in China nearly thirty years
我国近30年来植物迁地保护及其研究的综述
Predicting range shifts for critically endangered plants: Is habitat connectivity irrelevant or necessary?
DOI:10.1016/j.biocon.2021.109033 URL [本文引用: 1]
Genomic insights into inter- and intraspecific mating system shifts in Primulina
DOI:10.1111/mec.v31.22 URL [本文引用: 2]
Spontaneous interspecific hybridization and patterns of pollen dispersal in ex situ populations of a tree species (Sinojackia xylocapa) that is extinct in the wild
DOI:10.1111/cbi.2010.24.issue-1 URL [本文引用: 1]
Allozymic genetic diversity in Eurycorymbus caraleriei (Levl.) Rehd. et Hand.-Mazz., an endemic and dioecious tree in China
雌雄异株稀有植物伞花木(Eurycorymbus cavaleriei)自然居群的等位酶遗传多样性研究
