Multiple dimensions of dietary diversity in large mammalian herbivores
Multiple dimensions of dietary diversity in large mammalian herbivores
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DOI：
10.1111/1365-2656.13206
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发表时间：
2020-06-01
影响因子：
4.8
通讯作者：
Pringle, Robert M.
中科院分区：
文献类型：
--
作者：
Kartzinel, Tyler R.;Pringle, Robert M.
理论预测，营养专门化(即低饮食多样性)应该使消费群体对环境干扰敏感。然而，准确量化饮食组成的难度和定义的模糊性都使诊断专业化变得复杂：是什么让一种饮食“多样化”？我们试图在半干旱的东非稀树草原上的一个物种丰富的大型哺乳动物草食动物群落中描述分类饮食多样性(TDD)和系统发育饮食多样性(PDD)之间的关系。我们假设TDD和PDD在物种内和物种之间是正相关的，因为分类上的多样化饮食可能包括来自许多品系的植物。通过使用DNA元生物编码分析跨越多个季节收集的1,281个粪便样本，我们编制了25个同域大型草食物种的高分辨率饮食谱。对于每个种群，我们参考当地植物的DNA参考库来计算TDD和PDD。与我们的假设相反，TDD和PDD的度量要么相互不相关，要么相互负相关。因此，这些指标反映了物种内部和物种之间饮食专业化的不同维度。总的来说，与浏览器和非反刍动物相比，食草动物和反刍动物表现出更大的TDD，但更低的PDD。我们发现，除了四个物种(灰斑马、水牛、大象、格兰特瞪羚)外，所有物种的TDD和/或PDD都有显著的季节变化；然而，除了平原斑马中的一个物种外，所有物种的TDD和PDD的关系在不同季节都是一致的。我们的结果表明，分类学通才可以成为系统发育专家，反之亦然。饮食多样性的这两个维度表明，对于预测消费者将如何应对气候变化和其他环境扰动的努力，存在着截然不同的影响。例如，TDD低的种群可能对食物物种在系统发育上的‘随机’损失敏感，而PDD低的种群可能对不利整个植物谱系的环境变化相对更敏感--在分类学和系统发育维度上食物多样性低的种群可能是最脆弱的。
Theory predicts that trophic specialization (i.e. low dietary diversity) should make consumer populations sensitive to environmental disturbances. Yet diagnosing specialization is complicated both by the difficulty of precisely quantifying diet composition and by definitional ambiguity: what makes a diet 'diverse'?We sought to characterize the relationship between taxonomic dietary diversity (TDD) and phylogenetic dietary diversity (PDD) in a species-rich community of large mammalian herbivores in a semi-arid East African savanna. We hypothesized that TDD and PDD would be positively correlated within and among species, because taxonomically diverse diets are likely to include plants from many lineages.By using DNA metabarcoding to analyse 1,281 faecal samples collected across multiple seasons, we compiled high-resolution diet profiles for 25 sympatric large-herbivore species. For each of these populations, we calculated TDD and PDD with reference to a DNA reference library for local plants.Contrary to our hypothesis, measures of TDD and PDD were either uncorrelated or negatively correlated with each other. Thus, these metrics reflect distinct dimensions of dietary specialization both within and among species. In general, grazers and ruminants exhibited greater TDD, but lower PDD, than did browsers and non-ruminants. We found significant seasonal variation in TDD and/or PDD for all but four species (Grevy's zebra, buffalo, elephant, Grant's gazelle); however, the relationship between TDD and PDD was consistent across seasons for all but one of the 12 best-sampled species (plains zebra).Our results show that taxonomic generalists can be phylogenetic specialists, and vice versa. These two dimensions of dietary diversity suggest contrasting implications for efforts to predict how consumers will respond to climate change and other environmental perturbations. For example, populations with low TDD may be sensitive to phylogenetically 'random' losses of food species, whereas populations with low PDD may be comparatively more sensitive to environmental changes that disadvantage entire plant lineages-and populations with low dietary diversity in both taxonomic and phylogenetic dimensions may be most vulnerable of all.