Present address: Laboratoire ‘Evolution et Diversité Biologique’ EDB, BatIVR3b2, Université Paul Sabatier, 118 route de Narbonne, Toulouse 31062 cedex 9, France.
Origin and number of founders in an introduced insular primate: estimation from nuclear genetic data
Article first published online: 1 FEB 2008
© 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd
Volume 17, Issue 4, pages 1009–1019, February 2008
How to Cite
BONHOMME, M., BLANCHER, A., CUARTERO, S., CHIKHI, L. and CROUAU-ROY, B. (2008), Origin and number of founders in an introduced insular primate: estimation from nuclear genetic data. Molecular Ecology, 17: 1009–1019. doi: 10.1111/j.1365-294X.2007.03645.x
- Issue published online: 1 FEB 2008
- Article first published online: 1 FEB 2008
- Received 23 September2007; revision accepted 17 November 2007
- demographic history;
- founding event;
- genetic distances;
- Macaca fascicularis;
- Mauritius island;
Cynomolgus macaques (Macaca fascicularis) were introduced on the island of Mauritius between 400 and 500 years ago and underwent a strong population expansion after a probable initial founding event. However, in practice, little is known of the geographical origin of the individuals that colonized the island, on how many individuals were introduced, and of whether the following demographic expansion erased any signal of this putative bottleneck. In this study, we asked whether the current nuclear genome of the Mauritius population retained a signature that would allow us to answer these questions. Altogether, 21 polymorphic autosomal and sex-linked microsatellites were surveyed from 81 unrelated Mauritius individuals and 173 individuals from putative geographical sources in Southeast Asia: Java, the Philippines islands and the Indochinese peninsula. We found that (i) the Mauritius population was closer to different populations depending on the markers we used, which suggests a possible mixed origin with Java playing most probably a major role; and (ii) the level of diversity was lower than the other populations but there was no clear and consistent bottleneck signal using either summary statistics or full-likelihood methods. However, summary statistics strongly suggest that Mauritius is not at mutation–drift equilibrium and favours an expansion rather than a bottleneck. This suggests that on a short time scale, population decline followed by growth can be difficult to deduce from genetic data based on mutation–drift theory. We then used a simple Bayesian rejection algorithm to estimate the number of founders under different demographic models (exponential, logistic and logistic with lag) and pure genetic drift. This new method uses current population size estimates and expected heterozygosity of Mauritius and source population(s). Our results indicate that a simple exponential growth is unlikely and that, under the logistic models, the population may have expanded from an initial effective number of individuals of 10–15. The data are also consistent with a logistic growth with different lag values, indicating that we cannot exclude past population fluctuation.