Abstract Biodiversity is declining, with major causes identified as habitat loss and a reduction of habitat quality. Recent studies have shown that particularly species with specific habitat demands are suffering in this way. Accordingly, habitat specialists have been nominated as umbrella species, which because they represent a much larger number of species, are thought best to fulfil the requirements of nature conservation. However, species which are ecologically intermediate between habitat specialists and generalists, and typically form networks of populations on adjoining habitats, might suffer even more severely under rapid habitat fragmentation than those specialists which had for a long time already occurred as discrete populations. Today, most of these formerly more widely distributed intermediate species also exist only as small and isolated populations which, because of their increasing geographic isolation, cannot counterbalance local extinctions by recolonisation. Furthermore, these species are mostly equipped with relatively high genetic diversity that is maintained by continual exchange of individuals between local populations. However, this high level of genetic variability frequently decreases after the collapse of population networks – with negative effects on the viability of these species. Thus, factors at the population and molecular levels may lead that formerly common species vanish in the near future.

中文翻译：

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常见物种的消失：空旷的栖息地和遗传多样性的作用

摘要 生物多样性正在下降，主要原因是栖息地丧失和栖息地质量下降。最近的研究表明，特别是具有特定栖息地需求的物种正在遭受这种痛苦。因此，栖息地专家被提名为保护伞物种，因为它们代表了更多的物种，被认为最能满足自然保护的要求。然而，在栖息地专家和通才之间的生态中间物种，并且通常在相邻栖息地形成种群网络，在栖息地迅速破碎的情况下，可能比那些长期以来已经作为离散种群出现的专家遭受更严重的损失。今天，这些以前分布更广泛的中间物种中的大多数也仅作为小而孤立的种群存在，由于地理上的日益孤立，无法通过重新殖民来抵消当地的灭绝。此外，这些物种大多具有相对较高的遗传多样性，这是通过当地种群之间不断交换个体来维持的。然而，这种高水平的遗传变异性经常在种群网络崩溃后降低——对这些物种的生存能力产生负面影响。因此，种群和分子水平的因素可能导致以前常见的物种在不久的将来消失。这些物种大多具有相对较高的遗传多样性，通过当地种群之间不断的个体交流而得以维持。然而，这种高水平的遗传变异性经常在种群网络崩溃后降低——对这些物种的生存能力产生负面影响。因此，种群和分子水平的因素可能导致以前常见的物种在不久的将来消失。这些物种大多具有相对较高的遗传多样性，通过当地种群之间不断的个体交流而得以维持。然而，这种高水平的遗传变异性经常在种群网络崩溃后降低——对这些物种的生存能力产生负面影响。因此，种群和分子水平的因素可能导致以前常见的物种在不久的将来消失。