Endangered species in small habitat patches can possess high genetic diversity: the case of the Tana River red colobus and mangabey

Abstract

We used mtDNA sequence data from the Tana River red colobus and mangabey to determine how their population genetic structure was influenced by dispersal and habitat fragmentation. The colobus and mangabey are critically endangered primates endemic to gallery forests in eastern Kenya. The forests are a Pliocene-Pleistocene refugium that has recently undergone significant habitat loss and fragmentation due to human activities. We expected both primates to exhibit low levels of genetic diversity due to elevated genetic drift in their small populations, and to show a strong correspondence between genetic and geographic distance due to disruption of gene flow between forests by habitat fragmentation. Additionally, because mangabey females are philopatric, we expected their mtDNA variation to be homogeneous within forest patches but to be heterogeneous between patches. In contrast, colobus have a female-biased dispersal and so we expected their mtDNA variation to be homogeneous within and between forest patches. We found high levels of haplotype and nucleotide diversity as well as high levels of sequence divergence between haplotype groups in both species. The red colobus had significantly higher genetic variation than the mangabey did. Most of the genetic variation in both primates was found within forest fragments. Although both species showed strong inter-forest patch genetic structure we found no correspondence between genetic and geographic distances for the two primates. We attributed the high genetic diversity to recent high effective population size, and high sequence divergence and strong genetic structures to long-term habitat changes in the landscape.

Genetic evidence for spatio‐temporal changes in the dispersal patterns of two sympatric African colobine monkeys

“…Little is known about African colobine population genetic diversity and structure. The studies conducted so far have focused only on few colobus populations from eastern Africa (Harris et al, 2009; McDonald and Hamilton, 2010; Mbora and McPeek, 2010). Harris et al (2009) used both observational and genetic data to describe the complex dispersal system of a Colobus guereza population in Uganda, where the genetic structure of social groups is shaped by male‐mediated gene flow together with less common episodes of female dispersal.…”

“…McDonald and Hamilton (2010) examined the genetic diversity and phylogenetic relationships among Kenyan and Tanzanian Colobus angolensis palliatus populations. Only one study on red colobus ( Piliocolobus badius rufomitratus ) has been reported from the Tana River in Kenya, which evaluated mitochondrial diversity within this population (Mbora and McPeek, 2010).…”

Dispersal and genetic structure in a tropical small mammal, the Bornean tree shrew (Tupaia longipes), in a fragmented landscape along the Kinabatangan River, Sabah, Malaysia

“…However, the extent to which habitat fragmentation has a negative effect on the genetic structure and persistence of animal populations remains debated [6]. While some studies have demonstrated a pronounced effect of habitat fragmentation on species' population genetic structure (e.g., [7][8][9][10][11][12]), others have failed to detect these effects (e.g., [11,[13][14][15]). In this context, a better understanding of how and the degree to which fragmentation affects species will help to understand demographic processes that are triggered by fragmentation events.…”

Identification of Aves, Herpetofauna and Arthropods in Miangas Island (Indonesia), the borderline of Wallacea ecoregion

“…This condition becomes a serious note for conservationists. Miangas Island as a small habitat will affect genetic flow, genetic drift, and fitness and become a factor against extinction rate especially for endangered species (Mbora and McPeek 2010).…”