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When dispersal fails: unexpected genetic separation in Gibraltar macaques (Macaca sylvanus)
Lara Modolo1, Robert D Martin, Carel P van Schaik
1Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. modolo@gmx.net
Molecular Ecology
|February 25, 2009
Summary
Genetic structure exists between Barbary macaque social groups on Gibraltar, contrary to expectations for male-biased dispersal. Unexpected female dispersal and culling practices may influence genetic diversity and conservation outcomes.
Area of Science:
- Primate genetics
- Conservation genetics
- Behavioral ecology
Background:
- Barbary macaques (Macaca sylvanus) are endangered, with wild populations in Morocco and Algeria.
- A free-ranging colony exists on Gibraltar, isolated from wild populations and subject to historical population bottlenecks and introductions.
- Gibraltar's social groups offer a unique system to study in situ genetic consequences of dispersal in cercopithecines.
Purpose of the Study:
- To investigate the genetic structure among five social groups of Barbary macaques on Gibraltar.
- To compare genetic patterns between autosomal and mitochondrial DNA markers.
- To assess the extent and sex-bias of dispersal within the Gibraltar colony.
Main Methods:
- Utilized 14 polymorphic microsatellite loci for autosomal DNA analysis.
- Analyzed the hypervariable region I of the mitochondrial DNA control region.
- Employed classical summary statistics and Bayesian frameworks for genetic structure and dispersal analysis.
Main Results:
- Significant genetic structure was detected between Gibraltar's macaque social groups using autosomal markers.
- Mitochondrial DNA analysis revealed substantial genetic variation (70.2%) between social groups.
- Identified a small number of male immigrants and a few unexpected female immigrants, with dispersal patterns differing from typical cercopithecine expectations.
Conclusions:
- Male-biased dispersal alone does not explain the observed genetic structure; other factors are at play.
- Culling of dispersing males may impede genetic homogenization but could also select for specific behavioral traits.
- These findings have significant conservation implications, suggesting evolutionary changes may occur independently of inbreeding or genetic drift.
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