Stable isotope analyses reveal dense trophic species packing and clear niche differentiation in a malagasy primate community

Abstract

Understanding the mechanisms maintaining local species richness is a major topic in tropical ecology. In ecological communities of Madagascar, primates represent a major part of mammalian diversity and, thus, are a suitable taxon to study these mechanisms. Previous research suggested that ecological niche differentiation facilitates the coexistence of lemurs. However, detailed data on all species making up diverse local primate assemblages is rarely available, hampering community-wide tests of niche differentiation among Malagasy mammals. Here, we took an indirect approach and used stable isotopes as long-term indicators of individuals' diets to answer the question of whether trophic patterns and food-related mechanisms stabilize coexistence in a species-rich lemur community. We analyzed stable carbon and nitrogen isotopes in hair collected from eight syntopic lemurs in Kirindy Forest. We found that lemur species were well separated into trophic niches and ranged over two trophic levels. Furthermore, species were densely packed in isotopic space suggesting that past competitive interactions between species are a major structuring force of this dry forest lemur community. Results of other comparative studies on primates and our findings underline that-in contrast to communities worldwide-the structure and composition of lemur communities follow predictions of ecological niche theory. Patterns of competitive interactions might be more clearly revealed in Malagasy primate communities than elsewhere because lemurs represent a large fraction of ecologically interacting species in these communities. The pronounced trophic niche differentiation among lemurs is most likely due to intense competition in the past as is characteristic for adaptive radiations.

Foraging choices of vampire bats in diverse landscapes: potential implications for land‐use change and disease transmission

“…Yet, bats from these colonies showed essentially no δ 13 C overlap and substantial differences in isotopic niche widths, indicating that differences arise from foraging choices not variation in baseline isotopic levels of the same prey species (Table ; Figs and ). Similar niche differentiation over small spatial scales was observed in lemur communities in Madagascar (Dammhahn & Kappeler ). Both in the Amazon and on the coast, finding vampire bats with isotopic values similar to other wildlife that do not exploit anthropogenic food resources (fruit bats, sea lions, etc.)…”

Trophic niche differentiation and microhabitat utilization revealed by stable isotope analyses in a dry-forest bat assemblage at Ankarana, northern Madagascar

“…In contrast to other non-volant mammalian communities (Dammhahn & Kappeler 2013, community-wide trophic avoidance among species was less pronounced. A combination of mechanisms appeared to facilitate the coexistence of these species: (1) differentiation into two trophic levels and (2) utilization of different microhabitats by insectivorous bats.…”

Shared evolutionary origin of major histocompatibility complex polymorphism in sympatric lemurs

“…Microcebus berthae and M. coquereli appeared most similar based on helminth prevalence. They shared three of four helminth genera with both direct and indirect transmission routes, which may reflect the substantial overlap in their diets, that is the amount of fruit/animal matter (Dammhahn & Kappeler, ). Similarly, overlaps in helminth prevalence were previously described in C. medius and M. murinus (Schwensow, Dausmann et al., 2010), and largely confirmed here, with seven of eight helminth genera shared between species.…”

“…This community includes M. berthae and M. coquereli , which are solitary and spatially dispersed, more densely populated, pair‐living C. medius and M. murinus , which is socially more cohesive and exhibits the highest population densities (Dammhahn & Kappeler, ; Kappeler, Wimmer, Zinner, & Tautz, ; Markolf, Roos, & Kappeler, ; Fietz, ,; Eberle & Kappeler, , ). These four species exhibit different levels of ecological overlap in their diet and in their demography that is incongruent with their phylogeny (Dammhahn & Kappeler, ; Thiele et al., ). This constellation may therefore provide an opportunity to assess the importance of ecological overlap in explaining patterns of MHC variation in these species, given that diet, host population density and spatial proximity have all been indicated to affect the level of parasitism (e.g., Vitone, Altizer, & Nunn, ; Hughes & Page, ; Chen et al., ; Godfrey, ; Morand, ).…”

“…This constellation may therefore provide an opportunity to assess the importance of ecological overlap in explaining patterns of MHC variation in these species, given that diet, host population density and spatial proximity have all been indicated to affect the level of parasitism (e.g., Vitone, Altizer, & Nunn, ; Hughes & Page, ; Chen et al., ; Godfrey, ; Morand, ). A considerable overlap in helminth communities, dietary ranges and functional proximity of MHC alleles reported between M. murinus and C. medius (Schwensow, Dausmann et al., 2010; Dammhahn & Kappeler, ) suggest that their ecological similarities are potentially relevant to explain their MHC similarities. While the most common helminth genera identified in these hosts presumably show mild pathogenicity (Raharivololona & Ganzhorn, ; Irwin & Raharison, ), helminth infections appear to be associated with reduced survival in M. murinus (Hämäläinen, Raharivololona, Ravoniarimbinina, & Kraus, ).…”