生物多样性

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喜旱莲子草茎叶解剖结构从原产地到入侵地的变异式样

潘晓云1,梁汉钊1,Alejandro Sosa 2,耿宇鹏1,李博1,陈家宽1*   

  1. 1 (生物多样性和生态工程教育部重点实验室, 复旦大学生物多样性科学研究所, 上海 200433)
    2 (South American Biological Control Laboratory, USDA-ARS, Hurlingham-Buenos Aires 1868, Argentina)
  • 收稿日期:2005-10-24 修回日期:2006-03-23 出版日期:2006-05-20 发布日期:2006-05-20
  • 通讯作者: 陈家宽,潘晓云

Patterns of morphological variation of alligator weed (Alternanthera philoxeroides): from native to invasive regions

Xiaoyun Pan1, Hanzhao Liang , Alejandro Sosa2, Yupeng Geng1, Bo Li1, Jiakuan Chen1*   

  1. 1 Ministry of Education Key Laboratory for Biodiversity Science & Ecological Engineering, Institute of Biodiversity Sci-ence, Fudan University, Shanghai 200433, China
    2 South American Biological Control Laboratory, USDA-ARS, Hurlingham-Buenos Aires 1868, Argentina
  • Received:2005-10-24 Revised:2006-03-23 Online:2006-05-20 Published:2006-05-20
  • Contact: Jiakuan Chen,Xiaoyun Pan

摘要:

长期以来人们一直认为, 外来种入侵及其危害是由于一个物种从原产地到入侵地其环境因子改变(如天敌压力的减弱等)而导致的。近年来, 越来越多的研究者开始认识到, 生物入侵过程实际上是一个现代人类活动影响下的物种的快速进化过程, 生物入侵的进化遗传学已成为入侵生物学研究中最活跃的分支之一。作者比较了来自原产地(阿根廷)和入侵地(中国和美国)的喜旱莲子草(Alternanthera philoxeroides)的11个种群在茎、叶解剖结构方面的变异式样, 发现所研究的19个性状在原产地(阿根廷)和入侵地(中国和美国) 的变异情况明显不同: 在原产地种群中, 共有9个性状指标存在显著差异, 遗传率在49–89%之间, 这9个性状是气孔密度、气孔指数、茎直径、髓腔直径、维管柱直径、皮层厚度、维管柱面积比、髓腔面积比和叶形指数; 而在入侵地种群间, 19个性状指标均无明显差异。这表明喜旱莲子草从原产地到入侵地其遗传多样性降低; 入侵地喜旱莲子草种群间的形态变异主要为表型可塑性。根据19个形态指标对喜旱莲子草11个种群进行主成分分析和聚类, 结果显示: 所有入侵地种群和原产地的Ar1种群(Santa Fé, 59°49′W, 29°16′S)聚为一类, 原产地的Ar4 (Tandil, 59°03′ W, 37°11′ S)单独聚为一类, 原产地的其他4个种群聚为一类。表明Ar1种群可能与入侵中国的喜旱莲子草在基因型上更为接近。这一结果为进一步揭示喜旱莲子草入侵机理(如杂交适应性)和在原产地寻求对应天敌的生物防治工作提供了基础数据。

关键词: 分子生态学, 生物多样性, 保护生物学, 种群保护和恢复, 物种多样性

Abstract

The damage caused by biological invasions has traditionally been thought to result from alien species taking advantage of ecological differences between the native and introduced regions. In contrast, evidence is in-creasing that invasive plants can undergo rapid adaptive evolution during the process of range expansion. Using a common garden approach, we compared 19 morphological and anatomical traits of Alternanthera philoxeroides collected in native (Argentina) and invasive (China and USA) regions. The results show that native and invasive A. philoxeroides have become genetically differentiated. Populations from Argentina had significant morphological variation in nine traits, with heritability varying from 49% to 89%. The nine traits are stomatal density, stomatal index, diameter of stem, diameter of pith cavity, thickness of vascular cylinder, thickness of cortex, area ratio of vascular cylinder, area ratio of pith cavity, and leaf index. However, populations from introduced regions showed no significant variations in any of the 19 traits, indicating that the morphological differences within introduced regions might be based on phenotypic plasticity.Based on the result of PCA (primary component analysis), all five introduced populations and one population from Argentina (Santa Fé, 59°49′W, 29°16′S) can be clustered as one group, implying that the Santa Fé population may have similar genotypes with the lineage introduced to China. The existence of genetically differentiation of A. philoxeroides between native and introduced regions should be considered in any pro-grams that attempt management or utilization of this plant.

Key words: molecular ecology, biodiversity, conservation biology, population conservation and restoration, species diversity