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Dammhahn M.,Deutsches Primatenzentrum GmbH DPZ | Kappeler P.M.,Deutsches Primatenzentrum GmbH DPZ | Kappeler P.M.,University of Gottingen
American Journal of Physical Anthropology | Year: 2014

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. © 2013 Wiley Periodicals, Inc. Source

Dammhahn M.,Deutsches Primatenzentrum GmbH DPZ | Kappeler P.M.,Deutsches Primatenzentrum GmbH DPZ | Kappeler P.M.,University of Gottingen
American Journal of Physical Anthropology | Year: 2010

The relationships between resource distribution, type of competition, and consequences for social organization have been formalized in the socioecological model (SEM) which predicts that ecological factors are the main determinants of female distribution. We tested this basic prediction in two solitary primates (Microcebus berthae and M. murinus) which differ in female association patterns. Using stable nitrogen and carbon isotope data of hair samples and food sources we quantified inter-specific differences in diet. δ13C in M. berthae reflected a diet composed mainly of insect secretions. Higher within-species as well as seasonal variation in δ13C of M. murinus indicated a wider trophic niche including plant and animal source food. Constantly elevated δ15N in M. murinus most likely reflected extended torpor during the lean season. This energy-saving strategy together with a wider, more opportunistic feeding niche might reduce female competition in this species, facilitating smaller female ranges, and a higher association potential. In contrast, δ15N fluctuated seasonally in M. berthae, most likely indicating varying amounts of arthropod food in the diet. Intense scramble competition over small and seasonally limited resources might lead to female spatial avoidance and a reduced association potential in M. berthae. Thus, differences in female association patterns between these two solitary foragers are due to different types of competition and overall intensities of intra-specific competition. © 2009 Wiley-Liss, Inc. Source

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