Intraspecific dietary variation in niche partitioning within a community of ecologically similar snakes
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Intraspecific dietary variation in niche partitioning within a community of ecologically similar snakes Micah W. Perkins1 · Carl S. Cloyed2 · Perri K. Eason3 Received: 20 April 2020 / Accepted: 5 September 2020 © Springer Nature Switzerland AG 2020
Abstract Niche partitioning is an important mechanism for allowing ecologically similar species to coexist, contributing to biodiversity and the functioning of ecological communities. Species partition niches by taking advantage of environmental heterogeneity. However, niche partitioning and species coexistence investigations often do not include intraspecific variation or individual differences like sex and body size even though these factors can have important ecological consequences. Such intrapopulation factors can reduce the number of individuals among species that overlap in resource use and potentially facilitate coexistence. Using stable isotopes (δ13C and δ15N), we quantified dietary differences among three ecologically similar, sympatric watersnake species: Nerodia erythrogaster, N. rhombifer and N. sipedon. Additionally for each species, we determined intraspecific dietary patterns and determined how those within-species patterns may contribute to dietary niche partitioning among species. Nerodia erythrogaster fed more on terrestrial prey, while N. rhombifer fed at higher trophic levels. Females across species fed at higher trophic levels than did males, and isotopic variance differed between the sexes in N. sipedon. Larger watersnakes foraged at higher trophic levels and fed more on terrestrial prey. Each watersnake species had a distinct diet that overlapped to some degree with the other species’ diets, but these diets varied both between sexes and among size groups within species. This inter- and intraspecific dietary variation can facilitate species coexistence by reducing the number of individuals from all species that use the same resources. Intraspecific variation can add important and nuanced layers to the evolution of species coexistence, and research on interspecific niche relationships needs to increasingly consider the effects of these intraspecific variations. Keywords Coexistence · Dietary variation · Intraspecific · Niche partitioning · Ontogeny · Trophic level
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1068 2-020-10078-6) contains supplementary material, which is available to authorized users. * Micah W. Perkins [email protected] Extended author information available on the last page of the article
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Evolutionary Ecology
Introduction Niche partitioning is an important ecological concept in part because it can reconcile theoretical and laboratory studies that demonstrate competitive exclusion (Gause 1934; Hutchinson 1961; MacArthur and Levins 1967) with field observations and studies that demonstrate widespread coexistence among ecologically similar species (MacArthur 1958; Hutchinson 1959; Hardin 1960). Interspecific niche partitioning is ubiquitous in
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