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

Abstract

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.

Assessing evolutionary history and species boundaries in a polymorphic tropical lizard, the Aspidoscelis lineattissimus species complex (Squamata, Teiidae)

“…In addition to ancestral range estimation, to reconstruct the evolutionary history of the A. lineattissimus complex, it is necessary to consider some of the following biotic and abiotic components that were probably involved in the origin of the members of this complex: (i) all three confirmed monophyletic subspecies and the three well‐differentiated populations of A. l. duodecemlineatus (Clades III–V) are found in the warm valleys and lowlands of the coastal plains where the tropical deciduous forest predominates, with areas of xerophilous thorny scrub, and gallery forest adjacent to rivers (Raya‐García et al, 2020); (ii) intrinsic pre‐mating barriers to gene flow may exist in the form of documented unique femoral gland secretions that are more attractive to members (both sexes) of the same subspecies than to individuals representing different subspecies (Raya‐García et al, 2020); (iii) the abiotic component involves the main physiographic feature in the region, the western mountain range of the Sierra Madre del Sur, which meets the ocean and forms extensive sections of rocky cliffs along the western coastline of Mexico, comprising the range of the coastal species and their populations of the A. lineattissimus complex (Figure 1); (iv) ultimately, another of the mainly abiotic components is the historical climatic change that occurred during the Pliocene and Pleistocene, and its direct effect of which on the level of the ocean (Dowsett et al, 2005; Miller et al, 2005) is considered the main factor responsible for the reduction/expansion of the coastal plains and, therefore, the presence/absence of suitable habitats relevant to dispersal and/or the disjunction of the distribution area of the complex.…”

“…Here, this taxonomy has been questioned since we observed a high degree of overlap between subspecies in characters such as coloration pattern, size and disposition of the supraocular granules, as well as in meristic characters such as the number of femoral pores, mid‐dorsal scales and preanal scales (see Duellman & Wellman, 1960). However, a recent study supports the existence of pre‐mating barriers among populations of some of these subspecies based on the chemical composition of the male femoral gland secretions (Raya‐García et al, 2020). Above suggests, despite overlapping morphological character variations, each subspecies could be on its own independent evolutionary course and could, therefore, represent distinct species.…”

“…In addition, these recurrent fluctuations in ocean level may have caused vicariance and dispersal events that could in turn have caused adjacent populations to become isolated and/or come into contact. Indeed, in a hypothetical secondary contact event, there would have been a weak pre-mating barrier between the Cocinas Island (C) and Southwestern Coastal Plain (B2) populations, since females from these areas were not affected by interpopulation variation in certain chemical compounds of femoral secretions released by males, while there would have been a strong barrier between the subspecies of this complex (Raya- García et al, 2020). Finally, although we found no evidence of secondary contact among the populations of A. l. duodecemlineatus, the recognized limitations of our study imply that this finding cannot be considered conclusive.…”

“…Furthermore, the males of this species produce exclusive chemical signals (e.g. methyl oleate and dihydrolanosterol) with respect to other arboreal or terrestrial lizard species of tropical environments (Raya- García et al, 2021), and these compounds may play a role in species recognition and pre-mating reproductive isolation (Raya- García et al, 2020).…”

“…The many‐lined whiptail lizard Aspidoscelis lineattissimus is a bisexual endemic species, distributed in tropical areas throughout the western region of Mexico (Duellman & Wellman, 1960; García & Ceballos, 1994), a region of complex topography driven by geological and volcanic activity associated with the formation of the Trans‐Mexican Volcanic Belt and the Sierra Madre del Sur mountain chain (Figure 1; Ferrari et al, 1994). This diurnal, terrestrial and insectivorous species (Güizado‐Rodríguez & Casas‐Andreu, 2011) is distributed in tropical dry forests, xerophilous vegetation and gallery forests (Navarro‐García et al, 2008; Raya‐García et al, 2020). The snout–vent length of this species ranges from 42 to 112 mm, but the males reach sexual maturity at 51 mm and females at 62 mm (Ramírez‐Bautista et al, 2000).…”