动物生活史进化理论研究进展

综述了生活史性状、生活史对策、权衡、适合度及进化种群统计学等动物生活史进化领域的进展。权衡是生活史性状之间相互联系的纽带,分为生理权衡与进化权衡。适合度是相对的,与个体所处的特定环境条件有关,性状进化与适合度之间关系紧密。适合度是生活史进化理论研究的焦点。探讨动物生活史对策的理论很多,影响最大的是MacArthur和Wilson提出的r对策及K对策理论。随年龄的增长,动物存活率及繁殖率逐步下降的过程,称为衰老;解释衰老的进化理论主要有突变-选择平衡假设和多效对抗假设。进化种群统计学将种群统计学应用于生活史进化研究,为探讨表型适合度的进化提供了有效的手段。将进化种群统计学、数量遗传学及特定种系效应理论进行整合,建立完整的动物生活史进化综合理论体系,是当代此领域的最大挑战。     

The effects of selection,drift and genetic variation on life‐history trait divergence among insular populations of natterjack toad,Bufo calamita

Although loss of genetic variation is frequently assumed to be associated with loss of adaptive potential, only few studies have examined adaptation in populations with little genetic variation. On the Swedish west coast, the northern fringe populations of the natterjack toad Bufo calamita inhabit an atypical habitat consisting of offshore rock islands. There are strong among‐population differences in the amount of neutral genetic variation, making this system suitable for studies on mechanisms of trait divergence along a gradient of within‐population genetic variation. In this study, we examined the mechanisms of population divergence using Q_ST–F_ST comparisons and correlations between quantitative and neutral genetic variation. Our results suggest drift or weak stabilizing selection across the six populations included in this study, as indicated by low Q_ST–F_ST values, lack of significant population × temperature interactions and lack of significant differences among the islands in breeding pond size. The six populations included in this study differed in both neutral and quantitative genetic variation. Also, the correlations between neutral and quantitative genetic variation tended to be positive, however, the relatively small number of populations prevents any strong conclusions based on these correlations. Contrary to the majority of Q_ST–F_ST comparisons, our results suggest drift or weak stabilizing selection across the examined populations. Furthermore, the low heritability of fitness‐related traits may limit evolutionary responses in some of the populations.     

基于DNA条形码评估西双版纳国家级自然保护区对樟科植物进化历史的保护

为评估西双版纳国家级自然保护区对樟科这一重要植物类群进化潜力的保护情况, 揭示将物种进化历史纳入生物多样性保护评估的重要性, 本研究通过对西双版纳地区长期的野外调查并查阅标本记录与文献资料, 整理出该地区樟科13属121种物种的具体分布信息, 以植物条形码ITS序列作为分子标记构建了反映整个西双版纳地区樟科植物系统发育关系的系统发育树。我们以此为基础, 从物种层面分析了各物种的进化特异性(evolutionary distinctiveness, ED), 从区域层面分析了自然保护区内、外以及32个行政乡镇的系统发育多样性(phylogenetic diversity, PD), 并结合物种丰富度(species richness, SR)与物种濒危等级, 综合探讨了西双版纳国家级自然保护区对樟科植物进化历史的保护情况。研究发现, 西双版纳国家级自然保护区仅拥有整个西双版纳地区54.5%的樟科物种数, 却保护了该地区樟科植物约88.8%的进化历史, 没有被列入保护范围但却拥有高系统发育多样性的区域有打洛镇、易武乡等。就物种而言, 进化特异性相对较高的19个物种中, 有5种(26.3%)在自然保护区内没有分布; 濒危等级高的54个物种中, 有20种(37.0%)在自然保护区没有分布, 同时拥有高进化特异性和濒危等级的物种仅有1种不在保护区内分布。结果表明, 虽然西双版纳国家级自然保护区对樟科这一植物类群的系统发育多样性以及高保护价值物种的保护较好, 但仍有部分重要樟科植物的进化历史没有涵盖在现有自然保护区范围内; 按照传统方法设定的自然保护区虽能在一定程度上保护樟科物种的进化历史, 但仍然存在与标准化系统发育多样性保护策略相矛盾的地方。因此, 今后在建立自然保护区时, 应将系统发育多样性考虑在内, 以保护生物多样性应对环境变化的潜力。     

The comparative importance of species traits and introduction characteristics in tropical plant invasions

Aim We used alien plant species introduced to a botanic garden to investigate the relative importance of species traits (leaf traits, dispersal syndrome) and introduction characteristics (propagule pressure, residence time and distance to forest) in explaining establishment success in surrounding tropical forest. We also used invasion scores from a weed risk assessment protocol as an independent measure of invasion risk and assessed differences in variables between high‐ and low‐risk species. Location East Usambara mountains, Tanzania. Methods Forest transect surveys identified species establishing in disturbed and intact forest. Leaf traits (specific leaf area and foliar nutrient concentrations) were measured from leaves sampled in high‐light environments. Results A leaf traits spectrum was apparent, but species succeeding or failing to establish in either disturbed or intact forest were not located in different parts of the spectrum. Species with high invasion risk did not differ in their location on the leaf trait spectrum compared with low‐risk species but were more likely to be bird/primate‐dispersed. For 15 species establishing in forest quadrats, median canopy cover of quadrats where seedlings were present was correlated with a species value along the leaf trait spectrum. Species establishing in disturbed forest were planted in twice as many plantations and were marginally more likely to be bird‐ or primate‐dispersed than species failing to become established in disturbed forest. Establishment in intact forest was more likely for species planted closer to forest edges. Main conclusions Leaf and dispersal traits appear less important in the colonization of tropical forest than introduction characteristics. It appears, given sufficient propagule pressure or proximity to forest, alien species are much more likely to establish independently of leaf traits or dispersal syndrome in continental tropical forests.     

Life‐History Data in Bioindication Procedures,Using the Example of Hoverflies (Diptera,Syrphidae) in the Elbe Floodplain

This is the first study to relate syrphid life history traits to environmental variables with a multi‐trait approach. We aimed to answer two questions: 1. Do syrphid species respond to small scale changes in environmental variables in seasonally flooded grasslands in a Central European floodplain (Elbe)? 2. Can species response to environmental variables be explained by the biological characteristics of the species expressed by their life history traits? Despite their large mobility, syrphids did respond significantly to small scale changes in environmental variables (groundwater (GW) depth, cation exchange capacity, amplitude of variation of the GW‐depth). On the other hand, the biological traits of the syrphids did not sufficiently explain syrphid occurrence at the sites. Possible explanations are discussed and an outlook for further studies is given. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)