嵌套分布格局研究进展: 分析方法、影响机制及保护应用

基于物种分布或群落组成的嵌套格局(嵌套分布格局)是岛屿生物地理学和群落生态学的重要前沿研究领域和核心问题之一。嵌套分布格局最初起源于岛屿物种组成的研究, 是指物种较贫乏岛屿中的物种是物种较丰富岛屿中的物种的一个适当子集的分布模式。深入了解嵌套分布格局及其影响机制对生物多样性保护具有重要意义, 并可用于指导管理工作。近40年来, 嵌套分布格局备受生态学家和保护生物学家的关注, 并且在分析方法、影响机制、生物多样性保护应用等方面都取得了一系列重要进展。本文通过对文献的系统检索和归纳总结, 从4个方面对嵌套分布格局的最新研究进展进行了综述: (1)发展历史及其研究现状; (2)分析方法, 包括各个嵌套指数和零模型的优点与局限; (3)影响机制及其检验方法; (4)在生物多样性保护与管理中的应用。最后, 我们对该领域进行了归纳总结并对以后的发展方向提出了针对性建议, 包括选择最适合的嵌套指数和零模型进行嵌套分析、同时对多种嵌套理论假说进行验证、开展更多关于功能嵌套和谱系嵌套的研究、推动嵌套分布格局与其他相关领域的融合。本文对于深入了解嵌套分布格局的前沿进展, 以及推动国内该领域的快速发展将有重要意义。     

Influence of management on butterflies of rare grassland ecosystems in Germany

Traditional hay-meadows in the Alps and fens at the edge of the Alps are habitats for many rare and endangered butterfly species. Conservation efforts aim at preserving these species, but the biotopes depend on regular mowing, which in turn requires intensive financial support. The feasibility of substituting mowing of these sites by grazing is discussed and considered as a more cost effective management type which produces agriculturally valuable goods as well. In this study the butterfly fauna of mown and grazed sites were compared. Species composition, species number, and the occurrence of rare species under the two management types were in most cases rather similar for both grassland ecosystems. Nevertheless, there are hints that for single rare species this might not be true. Additionally, at one site, grazing intensity on a former hay-meadow was too high to preserve the species-rich community. Overall the results are encouraging: grazing does not have to be as detrimental as formerly thought, although details (compartments of pastures, intensity) still have to be confirmed. Experimental grazing management of aban-doned grasslands of the studied types should be started.     

Is there a core set of organisms that structure macroinvertebrate assemblages in freshwater wetlands?

1. We analysed taxa lists from 447 individual wetlands from several ecoregions across the world using nestedness and similarity‐based multivariate analyses. We examined how similar wetland assemblages are across regions, whether variation in assemblages is ordered (nested) or unpredictable (idiosyncratic), whether individual taxa occur predictably or unpredictably across wetland habitats, and if any of these patterns differed between temporary‐ and permanent water habitats.
2. We found that macroinvertebrate assemblages were highly nested (N = 0.947), but unexpectedly 37 of the 40 most widespread taxa (>10% occurrence) were idiosyncratic.
3. Of the 447 wetlands, we identified 277 that shared more than 40% similarities in assemblages, were mostly nested, and clustered together in ordination space, and thus could be considered a core set of wetlands in terms of assemblage structure. Assemblages in the 170 wetlands outside this core (mostly idiosyncratic) tended to be depauperate sites in arid or high elevation areas, or alternatively taxonomically rich sites supporting numerous lotic or lacustrine organisms.
4. The ‘Core’ itself split into two main parts, one comprised of wetlands from semi‐arid or mild climate areas dominated by strong flying insects, and the second comprised of wetlands from wetter, more northerly areas where non‐insects with passive dispersal were very prevalent. Climate and geology appear to be major controls on macroinvertebrate distributions across the set of 447 wetlands. Hydrology (temporary versus permanent) of wetlands was a lesser control on assemblage structure over the set of 447 wetlands.
5. That wetlands are dominated by about 40 widely‐occurring macroinvertebrate taxa, and those taxa tend to occur idiosyncratically, suggests that overall assemblages across wetlands may share many similarities, but some of widespread taxa may still be missing from many individual wetlands. Why these otherwise fairly ubiquitous taxa do not occur in specific wetlands may shed important light on how those wetlands are controlled ecologically; in other words, do sites lack specific factors required by these taxa?

     

Unexpected genetic diversity of Fallopia japonica from Central Europe revealed after AFLP analysis

Recently much attention has been paid to genetic aspects of invasive success in Japanese knotweed s.l. One hypothesis to explain the invasive spread of these species is a multiple introduction, which leads to a higher level of genetic diversity in the invaded range. Fallopia japonica is considered to be genetically uniform in Europe, introduced as a single female clone. However, there is some evidence suggesting that invasion history and dynamics differ between Western and Central-Eastern Europe. We used AFLP markers to characterize genetic diversity of three Fallopia taxa that occur in Poland: F. japonica, F. sachalinensis and their hybrid Fallopia × bohemica, growing in so-called ‘homogeneous’ populations, consisting of one taxon and ‘heterogeneous’ populations, composed of the three taxa cohabiting together. No polymorphism, resp. an insignificantly low variability was observed in the ‘homogeneous’ populations. In the ‘heterogeneous’ stands polymorphism was detected within each taxa, with one exception that concerns individuals of F. sachalinensis from a riparian habitat. The highest level of polymorphism was found among individuals of F. × bohemica. The most striking result of our study is the observation of polymorphism between individuals of F. japonica. The AFLP data also showed that F. × bohemica is most diverse when occurring in a heterogeneous configuration with F. japonica and F. sachalinensis in the same habitat. Our results are the first evidence of genetic diversity in F. japonica populations in Central Europe and can implicate the possibility of its multiple introduction in this region or the existence of sexual reproduction of this species.