Population Scent Discrimination in Two Liolaemus Lizard Species: Exploring Ethological Isolation

Abstract

Reproductive isolating barriers are a crucial element in the speciation process. From these barriers, and among those acting early in the speciation process (premating), the ethological ones can play a pivotal role in isolating populations or closely related species. In fact, the high diversity of some taxa has been correlated with an elevated divergence in sexual signals, which facilitates isolation. The present study explored whether variation in chemical signals may contribute to the high diversity of Liolaemus lizards, a genus with more than 290 species. Specifically, population scent discrimination was investigated in two sympatric species, L. tenuis and L. lemniscatus, studying the response of closely located populations most likely from the same genetic lineages. Lizards of both species discriminated between scents of their own and different populations, and in some cases, scents from their own population were preferred. These results suggest a fast evolution of scents and/or of their discrimination, implying that the ethological barriers involving the chemical modality may evolve fast. The studied species, however, differed in the strength of the exhibited population scent discrimination, suggesting that the ethological barriers may evolve at different rates across species. It can be concluded that ethological barriers involving chemical modality may disrupt species’ cohesion, potentially contributing to Liolaemus diversification, in synergy or not with geographical barriers.