When dispersal fails: unexpected genetic separation in Gibraltar macaques (Macaca sylvanus)

Abstract

Barbary macaques (Macaca sylvanus), now restricted in the wild to a few isolated forested areas of Morocco and Algeria, are present in a free-ranging colony on Gibraltar. For many decades, the Gibraltar colony was exposed to multiple bottlenecks due to highly nonrandom removal of animals, followed by repeated introductions of animals from North Africa. Moreover, because of complete isolation, Gibraltar's several social groups of macaques provide an ideal system to study the genetic consequences of dispersal in cercopithecines in situ. Predictions of genetic consequences due to male-biased dispersal in cercopithecines will be different for autosomal and maternally inherited genetic markers, such as the control region of the mitochondrial DNA. We used a panel of 14 highly polymorphic microsatellite loci and part of the hypervariable region I of the mitochondrial control region to estimate genetic structure between five social groups in Gibraltar. Surprisingly, for autosomal markers, both classical summary statistics and an individual-based method using a Bayesian framework detected significant genetic structure between social groups in Gibraltar, despite much closer proximity than wild Algerian and Moroccan populations. Mitochondrial data support this finding, as a very substantial portion of the total genetic variation (70.2%) was found between social groups. Using two Bayesian approaches, we likewise identified not only a small number of male first-generation immigrants (albeit less than expected for cercopithecines) but also unexpectedly a few females. We hypothesize that the culling of males that are more likely to disperse might slow down genetic homogenization among neighbouring groups, but may also and more perversely produce selection on certain behavioural traits. This may have important repercussions for conservation, as it could lead to evolutionary changes that are not due to inbreeding or genetic drift.

The effect of landscape features on population genetic structure in Yunnan snub‐nosed monkeys (Rhinopithecus bieti) implies an anthropogenic genetic discontinuity

“…Among internal causes, social structure is a key issue which is largely mediated by social behaviour (reproductive skew, dispersal, group fission and fusion patterns) (Lampert et al. 2003; Modolo et al. 2008).…”

“…National Highway 214 forms a major habitat gap separating S1 and S2 from Fine-scale population structure is common in large mammals and can been influenced by various internal and external factors (Macey et al 1998;Hendry et al 2008;Jin et al 2008). Among internal causes, social structure is a key issue which is largely mediated by social behaviour (reproductive skew, dispersal, group fission and fusion patterns) (Lampert et al 2003;Modolo et al 2008). In the Rhinopithecus genus, wild groups are typically based on small family units of five to15 individuals composed of a single male and multiple females and their offspring (referred to as a one male unit or OMU).…”

Relatively Recent Evolution of Pelage Coloration in Colobinae: Phylogeny and Phylogeography of Three Closely Related Langur Species

“…Besides ecological factors, also social structure largely influences population genetic structure, which is mediated mainly by social behavior (reproductive skew, dispersal, fission and fusion patterns) [53], [68]–[71]. In most colobines, including species of the genus Trachypithecus , females tend to stay in their natal groups (female philopatry) and males migrate at time of sexual maturity [15], [16], leading to significant population differentiation when solely maternally-inherited markers as the herein applied HVI region are studied [68], [71].…”

“…In most colobines, including species of the genus Trachypithecus , females tend to stay in their natal groups (female philopatry) and males migrate at time of sexual maturity [15], [16], leading to significant population differentiation when solely maternally-inherited markers as the herein applied HVI region are studied [68], [71]. Thus, male-mediated gene flow is not captured in our study and accordingly to fully understand the evolutionary history of these three species further investigations should apply nuclear loci as well.…”

Editorial and retrospective 2008

“…2008), Anolis roquet (Johansson et al . 2008), the rock‐dwelling rodent Ctenodactylus gundi (Nutt 2008), Gibraltar macaques (Modolo et al . 2008) and Yellowstone grey wolves (Vonholdt et al .…”