The genetic population structure of wild western lowland gorillas (Gorilla gorilla gorilla) living in continuous rain forest

Abstract

To understand the evolutionary histories and conservation potential of wild animal species it is useful to assess whether taxa are genetically structured into different populations and identify the underlying factors responsible for any clustering. Landscape features such as rivers may influence genetic population structure, and analysis of structure by sex can further reveal effects of sex-specific dispersal. Using microsatellite genotypes obtained from noninvasively collected fecal samples we investigated the population structure of 261 western lowland gorillas (WLGs) (Gorilla gorilla gorilla) from seven locations spanning an approximately 37,000km2 region of mainly continuous rain forest within Central African Republic (CAR), Republic of Congo and Cameroon. We found our sample to consist of two or three significantly differentiated clusters. The boundaries of the clusters coincided with courses of major rivers. Moreover, geographic distance detoured around rivers better-explained variation in genetic distance than straight line distance. Together these results suggest that major rivers in our study area play an important role in directing WLG gene flow. The number of clusters did not change when males and females were analyzed separately, indicating a lack of greater philopatry in WLG females than males at this scale.

Origin of the HIV-1 group O epidemic in western lowland gorillas

“…Alternatively, it is possible that following its introduction, SIVgor may have not yet spread beyond southern Cameroon. The home ranges of gorilla groups are small compared with chimpanzees, and their movements, as inferred from gene flow, are influenced by both major and smaller rivers, perhaps more so than the migration of chimpanzees (28)(29)(30). It has been estimated that SIVgor sequence distances reflect at least 100-200 y of diversification (15).…”

Great ape Y Chromosome and mitochondrial DNA phylogenies reflect subspecies structure and patterns of mating and dispersal

“…Autosomal analysis has typically focused on analysis of short tandem repeats (STRs) (e.g., Becquet et al 2007;Nater et al 2013;Fünfstück et al 2014), with increasing numbers of whole-genome sequences recently becoming available (Prado-Martinez et al 2013;Xue et al 2015) and providing a rich picture of population structure and demographic history. Maternally inherited mitochondrial DNA (mtDNA) has also been widely exploited, progressing from sequencing of the hypervariable regions (Fischer et al 2006) to the maximum possible resolution of the whole molecule (Hvilsom et al 2014).…”

The sampling scheme matters: Pan troglodytes troglodytes and P. t. schweinfurthii are characterized by clinal genetic variation rather than a strong subspecies break

“…Field researchers thus correctly identified chimpanzee dung in 227/242 = 94% of cases. In a reciprocal analysis of genotypes purportedly from gorillas and typed as part of a complementary study (Fünfstück et al, 2014), we found 16 samples were derived from chimpanzees. These 16 samples were secondarily genotyped at microsatellite loci used here.…”

“…Finally, we compared the genetic differentiation between groups drawn from the same subspecies and between groups drawn from different subspecies. Such use of various methods is highly recommended for attempting to obtain an unbiased, accurate and comprehensive view about the genetic structure of the populations under study (Frantz et al, 2009; Schwartz and McKelvey, 2009; Fünfstück et al, 2014). …”