Genetic structure of an isolated population of mantled howler monkeys (Alouatta palliata) on Barro Colorado Island, Panama

Abstract

Habitat fragmentation may influence genetic variability through reductions in population size and the physical isolation of conspecifics. We explored the effects of these factors on genetic diversity in a population of mantled howler monkeys (Alouatta palliata) on Barro Colorado Island (BCI), Panama. The study population was established in 1914 when an unknown number of resident individuals were isolated from the surrounding mainland by damming of the Río Chagres to create the Panama Canal. Analyses of 10 microsatellite loci indicated that, despite this isolation, the howler monkeys on BCI exhibit levels of genetic diversity (H S = 0.584 ± 0.063) among the highest reported for any species of Alouatta. These data also revealed that although relatedness among adults in a social group was significantly greater than zero, the BCI population is not highly genetically structured. Tests for genetic bottlenecks based on departures from equilibrium expectations failed to reveal evidence of a recent reduction in population size. In contrast, coalescent modeling indicated that this population has likely experienced a marked decline within the last few 100 years. These findings generate new insights into the genetic structure of A. palliata and suggest that while the formation of BCI may not have substantially reduced genetic variation in these animals, genetic diversity has been influenced by historical changes in population size.

Genetic data suggest a natural prehuman origin of open habitats in northern Madagascar and question the deforestation narrative in this region

“…Similarly Lawler (80) concluded that P. verreauxi also suffered from a bottleneck less than 2,000 y ago in the southwest of Madagascar, again, a region where human impact and deforestation are more serious than in Daraina (14). Similar results have also been suggested for other primates [orangutans (81) and howler monkeys (82)]. In all these species [detection of a more ancient population size change is discussed elsewhere (46,47)], the population bottleneck has been reasonably attributed to recent human-driven changes.…”

“…To compare alternative scenarios and identify the most likely scenario within a Bayesian framework, we performed a BF analysis (e.g., ref. 82). A BF of 1 indicates that the two hypotheses are equally probable, whereas values greater than 1 would favor H1 and values less than 1 would favor H2.…”

Kin structure and parallel dispersal in the black-and-gold howler monkey Alouatta caraya (Platyrrhini, Atelidae)

“…The lack of a fragmentation effect, and high genetic diversity (mean H O = 0.65) were also found for the red-handed howler (Alouatta belzebul) in populations from the low Tocantins River, eastern Amazonia (Bastos et al, 2010). An isolated population of the mantled howler monkey, A. palliata, from Barro Colorado Island also presented high levels of genetic diversity (H E = 0.584 ± 0.063) and no effect of fragmentation (Milton et al, 2009). …”

Genetic Diversity of Neotropical Primates: Phylogeny, Population Genetics, and Animal Models for Infectious Diseases

“…Subsequent studies were carried out with mtDNA or microsatellite markers in A. belzebul [Nascimento et al, 2005[Nascimento et al, , 2008, Alouatta caraya [Nascimento et al, 2005[Nascimento et al, , 2007Inglêz 2006;Ascunce et al, 2007;Ruiz-Garcia et al, 2007], A. seniculus , Alouatta palliata and Alouatta macconnelli [Ruiz-Garcia et al, 2007], and A. palliata [Winkler et al, 2004;Milton et al, 2009], and with DNA sequence data of ␣ -fibrinogen [Gonçalves et al, 2008].…”