Contest versus scramble competition for mates: The composition and spatial structure of a population of gray mouse lemurs (Microcebus murinus) in North-west Madagascar |
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Authors: | Ute Radespiel Petra Ehresmann Elke Zimmermann |
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Institution: | 1. Institute of Zoology, Tier?rztliche Hochschule Hannover, Bünteweg 17, 30559, Hannover, Germany
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Abstract: | The modes of intrasexual competition interacting in many dispersed societies of nocturnal solitary foragers are still poorly
understood. In this study we investigate the spatial structure within a free-living population of gray mouse lemurs (Microcebus murinus) in order to test for the first time the predictions from two contrasting models of male intrasexual competition on the population
level. The contest competition model predicts an uneven distribution of the sexes in a population nucleus with a female biased
sex ratio in the center and a male biased sex ratio in the periphery. In contrast the scramble competition model predicts
males and females being distributed evenly throughout their habitat with a constant sex ratio. Nine capture/recapture periods
within three consecutive mating seasons revealed a continuous male biased sex ratio in the adult population with even trapping
rates for the sexes. The male biased sex ratio could either be explained with postnatal female biased mortality or with a
male biased natal sex ratio. This male biased sex ratio was apparent in all parts of the study site, indicating that the population
was not subdivided into a female biased core and a male biased periphery. Furthermore, the majority of adult males have been
captured at the same site as or in vicinity to females. Consequently, a large proportion of males had spatial access to females
during the mating season. No signs of monopolization of females by certain dominant males could be detected. These data support
the predictions from the scramble competition model and the concept of a promiscuous mating system for this species. |
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Keywords: | Microcebus murinus Primates Contest competition Scramble competition Mating system |
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