Molecular divergence between insular and continental Pudu deer ( <i>Pudu puda</i> ) populations in the Chilean Patagonia

Abstract

Island–continent isolation scenarios have played major roles in the understanding and development of evolutionary theories. During the last glacial maximum (LGM) in southern Chile, ice sheet advances and retreats formed the Patagonian archipelago along the southern Pacific Ocean. Chiloé Island is the largest island from the archipelago isolated from the continent by a narrow and shallow stretch of ocean. Pudu puda is a species endemic to Chile and part of Argentina, distributed along the Valdivian Temperate rainforest. We used mtDNA control region (654 bp) and cytochrome b (734 bp) sequences to understand the consequences in the evolutionary history and population structure of Pudu puda island–continent isolation. Bayesian and Maximum Likelihood phylogenetic analysis revealed two divergent clades corresponding to the continent and Chiloé Island. The Median Joining Network also supports these findings with an isolation of 10 mutational steps between Chiloé and the continent. We also found a significant high genetic structure (Φst = 0.75) and a sequence divergence percentage of 2.3% between the two clades. On the other hand, on the continent we found high haplotype genetic diversity (H = 0.9790 ± 0.0103) but no clear geographical population structure or phylogenetic clades. Our results suggest that the southern Pudu deer populations were isolated since the interglacial period (less than 0.5 million years ago) from the continent leading to two reciprocally monophyletic clades. We propose two subspecies to be considered in the development of future conservation programs for the species.