First records of pigmentation anomalies in the marsh deer at its southernmost stronghold: a warning message?

Abstract

Pigmentation anomalies (e.g., albinism, leucism) in Neotropical mammals are considered rare. Identifying the spatiotemporal distribution and prevalence of pigmentation anomalies is important to better assess the evolutionary basis of color variation. The southernmost population of the marsh deer (Blastocerus dichotomus) occurs within a relatively small area (< 2700 km2) of the Delta of the Paraná River, being fragmented into three subpopulations with low gene flow among them. Typically, the marsh deer has a brownish red to bright rufous chestnut-colored coat; at least two albino individuals have been reported in other populations of the species, but other anomalous colorations (i.e., leucism) have not been described for this species. Here, we present seven records of leucistic marsh deer from the Delta of the Paraná River, with the coloration of these individuals showing different levels of contrast from typically pigmented conspecifics. The presence of the leucistic phenotype in this population could be the product of its high level of homozygosis, but further studies are needed to confirm this relationship. Since the observed leucistic individuals were adults and apparently of breeding age, the possible maladaptive condition of this phenotype in this population remains to be evaluated.