Chemical signal divergence among populations influences behavioral discrimination in the whiptail lizard Aspidoscelis lineattissimus (squamata: teiidae)

Abstract

Signal divergence and sensory preferences may lead to sexual isolation and eventually promote speciation between animal populations. However, few studies have quantified the degree of chemical signal divergence and scent-mediated sexual isolation in lizard populations. Geographic and ecological variations among populations of the whiptail lizard Aspidoscelis lineattissimus suggest that there might be chemical signal divergence among these populations. Here, we used gas chromatography-mass spectrometry to characterize and compare the chemical composition of the femoral gland secretions of male whiptail lizards of four populations from a western region of Mexico and, through behavioral experiments, explored the effects of lizard scents on precopulatory behaviors and intrasexual male-male chemical recognition among populations. Our results showed that males of each population contain a divergent mixture of compounds in their femoral gland secretions. Differential chemosensory behavior indicated that male and female lizards discriminated and were more attracted to scents of lizards from their same population. Although females also seem to discriminate male scents between populations, their associated preference to territories scent-marked by males of their own population is different between regions (eastern vs western) and not between populations. We suggest that between some populations of A. lineattissimus there may be partial premating isolation mediated by chemical signals and behavioral divergence. Geographic variation in sexual signals can strongly affect discrimination and recognition abilities among reproductive individuals from divergent populations, resulting in sexual isolation and speciation. Studies suggest that reproductive isolation and speciation in lizard systems may be mediated by chemical signals, male mate preferences, and male-male interactions but not by female mate preferences. Using gas chromatography-mass spectrometry techniques and behavioral experiments, we found that chemical divergence in femoral gland secretions of male Aspidoscelis lineattissimus influences behavioral discrimination among four distinct populations. Males and females recognized and responded more toward lizard scents from their own population. In addition, some female populations were able to discriminate between territories scent-marked by males from different populations. We suggest that chemical and behavioral differences between populations may influence partial premating isolation, which can be mediated by inter and intrasexual interactions.