Landscape genetics shows that Tanzanian forest monkeys feel the heat of human influence

A new publication appearing in Heredity applies new methods for associating population genetic data with landscape resistance to an tropical, endangered species.
The authors utilize multiple measurements of landscape resistance, like forest cover and distance from the nearest village, to select the best-fit model of resistance for the microsatellite genetic data from five forest blocks of endangered Udzungwa red colobus monkeys (Procolobus gordonorum). Methods that use landscape resistance values are often complicated by the subjective nature of choosing relevant variables or the scale/direction of effect, but the methodology used by Ruiz-Lopez, Barelli et al. (ResistanceGA) selects models of resistance with no a priori assumptions and can use both categorical and continuous resistance surfaces (cool!).
While genetic diversity among forest blocks was similar, genetic differentiation was apparent. The genetic distance between these blocks was best explained by both the distance to the nearest village and the density of fire events. This result fits nicely into a “humans did it” narrative, but the authors show caution when making interpretations of variables that have both contemporary and historical contributions:

Although it is tempting to conclude from these results that human-mediated forest fragmentation is the primary driving force of Udzungwa red colobus monkey genetic differentiation, this is not necessarily the case. In fact, it is possible that some of the fragmentation is natural and quite old, but in such cases human settlement and activity in the intervening matrix habitats has likely maintained fragmentation and is contributing substantially to driving genetic differences among forests.

Ruiz-Lopez, M. J., Barelli, C., Rovero, F., Hodges, K., Roos, C., Peterman, W. E., & Ting, N. (2015). A novel landscape genetic approach demonstrates the effects of human disturbance on the Udzungwa red colobus monkey (Procolobus gordonorum). Heredity.

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