Low redundancy in seed dispersal within an island frugivore community
Low redundancy in seed dispersal within an island frugivore community
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DOI：
10.1093/aobpla/plv088
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发表时间：
2015-01-01
期刊：
影响因子：
2.9
通讯作者：
Drake, Donald R.
中科院分区：
文献类型：
--
作者：
McConkey, Kim R.;Drake, Donald R.
岛屿生态系统的特点是物种多样性低，这可能导致社区内功能冗余程度低。狐蝠（大型果蝠）是大种子物种的重要种子传播者，但它们在岛屿群落中的冗余从未被明确测试过。在一个太平洋群岛，我们发现狐蝠是唯一有效的传播者，57%的植物物种的水果，他们消费。它们对这些物种的传播至关重要，因为它们处理了超过90%的食用水果，或者是唯一一种将种子从母体树冠上沉积下来的动物，或者两者兼而有之。狐蝠对大种子果实（>13 mm宽）尤其重要，76%的食用物种依赖狐蝠传播，而小种子物种则为31%。随着狐蝠数量的减少，它们在变得稀少之前很久就停止了传播的功能。我们比较了种子传播的有效性（测量的比例扩散超出父母冠）的所有食果动物的四种植物的网站，狐蝠，并没有，功能性灭绝。在低和高丰度，狐蝠消耗这些物种的大部分可用的水果，但处理的散生孢子分散远离父母冠（质量）的比例显着降低，在低丰度。由于替代消费者（鸟类，啮齿动物和陆蟹）无法补偿时，飞狐功能性灭绝的传播者，我们的结论是，几乎没有多余的种子传播功能的飞狐在这个岛屿系统，并可能在其他岛屿上，他们发生。鉴于海洋岛屿群落往往比大陆群落简单，评估岛屿上不同生态功能的冗余程度极为重要。
The low species diversity that often characterizes island ecosystems could result in low functional redundancy within communities. Flying foxes (large fruit bats) are important seed dispersers of large-seeded species, but their redundancy within island communities has never been explicitly tested. In a Pacific archipelago, we found that flying foxes were the sole effective disperser of 57 % of the plant species whose fruits they consume. They were essential for the dispersal of these species either because they handled >90% of consumed fruit, or were the only animal depositing seeds away from the parent canopy, or both. Flying foxes were especially important for larger-seeded fruit (>13 mm wide), with 76 % of consumed species dependent on them for dispersal, compared with 31 % of smallseeded species. As flying foxes decrease in abundance, they cease to function as dispersers long before they become rare. We compared the seed dispersal effectiveness (measured as the proportion of diaspores dispersed beyond parent crowns) of all frugivores for four plant species in sites where flying foxes were, and were not, functionally extinct. At both low and high abundance, flying foxes consumed most available fruit of these species, but the proportion of handled diaspores dispersed away from parent crowns (quality) was significantly reduced at low abundance. Since alternative consumers (birds, rodents and land crabs) were unable to compensate as dispersers when flying foxes were functionally extinct, we conclude that there is almost no redundancy in the seed dispersal function of flying foxes in this island system, and potentially on other islands where they occur. Given that oceanic island communities are often simpler than continental communities, evaluating the extent of redundancy across different ecological functions on islands is extremely important.