Reevaluation of the status of the Central American brocket deer Mazama temama (Artiodactyla: Cervidae) subspecies based on morphological and environmental evidence

The Central American brocket deer (Mazama temama) is widespread across the Mesoamerican forests, yet it remains largely unknown. Three subspecies are recognized currently within M. temama using pelage coloration as the primary diagnostic character. However, it remains unclear if there is any pattern of morphological variation throughout its distribution. We compared two models of morphological subdivision, namely the traditional subspecies and another based on biogeographic provinces via 2D geometric morphometrics and ecological niche modeling. The second model presented a better fit to the observed variation in cranial shape and size. We found divergence in skull size between individuals from Mexico and Guatemala (northern group) relative to specimens from Honduras, Nicaragua, Costa Rica, and Panama (southern group), the latter being 8% larger than the northern group. Centroid size showed a significant correlation with geographic distance suggesting an isolation-by-distance pattern. Low geographical overlap between the two clusters suggests niche conservatism. Late Pleistocene dispersal from South to Central America and differences in available resources with subsequent isolation due to climatic barriers therefore may have promoted differentiation in size albeit without extensive changes in shape. In this context, the Motagua-Polochic-Jolotan fault system probably plays a key role in promoting morphological differentiation by climatic isolation. Finally, we suggest that M. t. temama () and M. t. reperticia should remain as valid names for the two morphological and ecologically differentiated groups detected here.

Automated summary

The Central American brocket deer is a widely distributed but poorly understood species. This study compared two models of morphological subdivision and found that the second model, based on biogeographic provinces, better fit the observed variation in cranial shape and size. The study suggests that differences in available resources and climatic barriers have promoted morphological differentiation in this species.