Department of Natural Resources Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada.
Instituto del Mar del Perú, Callao, Peru.
Sci Rep. 2024 Apr 3;14(1):7899. doi: 10.1038/s41598-024-57339-w.
Hutchison's niche theory suggests that coexisting competing species occupy non-overlapping hypervolumes, which are theoretical spaces encompassing more than three dimensions, within an n-dimensional space. The analysis of multiple stable isotopes can be used to test these ideas where each isotope can be considered a dimension of niche space. These hypervolumes may change over time in response to variation in behaviour or habitat, within or among species, consequently changing the niche space itself. Here, we use isotopic values of carbon and nitrogen of ten amino acids, as well as sulphur isotopic values, to produce multi-isotope models to examine niche segregation among an assemblage of five coexisting seabird species (ancient murrelet Synthliboramphus antiquus, double-crested cormorant Phalacrocorax auritus, Leach's storm-petrel Oceanodrama leucorhoa, rhinoceros auklet Cerorhinca monocerata, pelagic cormorant Phalacrocorax pelagicus) that inhabit coastal British Columbia. When only one or two isotope dimensions were considered, the five species overlapped considerably, but segregation increased in more dimensions, but often in complex ways. Thus, each of the five species occupied their own isotopic hypervolume (niche), but that became apparent only when factoring the increased information from sulphur and amino acid specific isotope values, rather than just relying on proxies of δN and δC alone. For cormorants, there was reduction of niche size for both species consistent with a decline in their dominant prey, Pacific herring Clupea pallasii, from 1970 to 2006. Consistent with niche theory, cormorant species showed segregation across time, with the double-crested demonstrating a marked change in diet in response to prey shifts in a higher dimensional space. In brief, incorporating multiple isotopes (sulfur, PC1 of δN [baselines], PC2 of δN [trophic position], PC1 and PC2 of δC) metrics allowed us to infer changes and differences in food web topology that were not apparent from classic carbon-nitrogen biplots.
赫奇逊的生态位 niche 理论认为，共存的竞争物种占据非重叠的超体积 hypervolume，这是一个理论空间，包含超过三个维度，存在于 n 维空间中。分析多个稳定同位素可以用来检验这些想法，其中每个同位素可以被视为生态位空间的一个维度。这些超体积可能会随着时间的推移而变化，以响应行为或栖息地的变化，在物种内部或之间，从而改变生态位空间本身。在这里，我们使用十种氨基酸的碳和氮的同位素值以及硫同位素值来产生多同位素模型，以检查栖息在不列颠哥伦比亚省沿海地区的五种共存海鸟物种（古鸻 Synthliboramphus antiquus、双冠鸬鹚 Phalacrocorax auritus、Leach's 暴风鹱 Oceanodrama leucorhoa、黑脚信天翁 Cerorhinca monocerata、普通鸬鹚 Phalacrocorax pelagicus）之间的生态位隔离。当只考虑一个或两个同位素维度时，这五个物种重叠程度相当大，但在更多维度上的隔离程度增加了，但通常是以复杂的方式增加。因此，这五个物种中的每一个都占据了自己的同位素超体积（生态位 niche），但只有当考虑到增加的来自硫和氨基酸特定同位素值的信息，而不仅仅是依赖于δN 和δC 的代理值时，这一点才变得明显。对于鸬鹚来说，两种鸬鹚的生态位大小都有所减少，这与它们的主要猎物太平洋鲱 Clupea pallasii 从 1970 年到 2006 年的减少是一致的。与生态位理论一致的是，鸬鹚物种在时间上表现出隔离，双冠鸬鹚对食物的变化表现出明显的变化，以适应更高维空间中的猎物变化。简而言之，包含多个同位素（硫、δN 的 PC1 [基线]、δN 的 PC2 [营养位]、δC 的 PC1 和 PC2）指标使我们能够推断出食物链拓扑结构的变化和差异，而这些变化和差异从经典的碳-氮生物图中并不明显。
