Hybridization patterns and evolutionary clues in broad-snouted caiman and yacare caiman: Insights from phylogeographic and ecological analyses

Abstract

Our study explores the dynamics of introgressive hybridization between two sympatric crocodilian species, Caiman latirostris and Caiman yacare, shedding light on the ongoing genetic exchange. Hybrid individuals exhibit a notable absence of distinct boundaries between parental and hybrid forms, potentially influenced by factors like limited dispersal potential or unexplored extrinsic variables. Despite sympatric coexistence, the species occupy distinct ecological niches, limiting hybridization. Climatic factors, particularly during autumn and winter, may further impact migration and energy allocation, contributing to the observed introgression pattern. Significantly, the prevalence of individuals with hybrid index values indicates introgressive hybridization between C. yacare and C. latirostris populations, supported by ecological niche models that found wide areas with potential for hybridization across much of their distribution. The range of hybrid index values suggests gene flow and the transfer of adaptive traits through hybridization. The divergence between C. yacare and C. latirostris, approximately 26 million years ago, aligns with geological and climatic changes during the Oligocene. Furthermore, our findings support a directional radiation pattern in C. latirostris populations from south to north, influenced by climatic changes and ecological niche shifts. This study revealed the dynamics of introgressive hybridization between C. yacare and C. latirostris, emphasizing the complex interplay of ecological, temporal, and environmental factors in shaping genetic patterns and evolutionary history.