Kinship and Dispersal Patterns in Alouatta caraya Inhabiting Continuous and Fragmented Habitats of Argentina

Abstract

Black and gold howler monkeys (Alouatta caraya) still inhabit degraded and fragmented forests in southern South America. This fact raises questions regarding the real capacity of the howler’s long-term survival under such conditions. A detailed molecular study was carried out with the aim of evaluating how the continuous processes of habitat reduction and fragmentation affect the genetic structure of howler monkey populations. Two populations exposed to differences in forest continuity were compared using molecular markers: one inhabiting an undisturbed and continuous forest (CF) and the other a fragmented forest (FF). FF and CF showed differences in kinship relations and dispersal patterns. The groups in the FF were genetically differentiated; in contrast, there was no differentiation between groups in the CF. Moreover, both males and females disperse in the CF; accordingly, most groups were composed of adult individuals that were not closely related, whereas in the FF, males disperse more than females and groups were composed of closely related adult females. These results suggest that habitat fragmentation modifies the dispersal patterns of black and gold howler monkeys and might reflect a trend towards a reduction in their ability to disperse. This study underscores the use of molecular genetic data as a tool of utmost importance for conservation purposes to better understand social organization and behavioral patterns.