Female mate choice based on pheromone content may inhibit reproductive isolation between distinct populations of Iberian wall lizards

Abstract

The Iberian wall lizard Podarcis hispanica forms part of a species complex with several morphologically and genetically distinct types and populations, which may or may not be reproductively isolated. We analyzed whether female mate choice based on males’ chemical signals may contribute to a current pre-mating reproductive isolation between two distinct populations of P. hispanica from central Spain. We experimentally examined whether females choose to establish territories on areas scent-marked by males of their own population, versus areas marked by males of the other population. Results showed that females did not prefer scent-marks of males from their own population. In contrast, females seemed to attend mostly to among-individual variation in males’ pheromones that did not differ between populations. Finally, to test for strong premating reproductive isolation, we staged intersexual encounters between males and females. The population of origin of males and females did not affect the probability nor the duration of copulations. We suggest that the different environmental conditions in each population might be selecting for different morphologies and different chemical signals of males that maximize efficiency of communication in each environment. However, females in both populations based mate choice on a similar condition-dependent signal of males. Thus, male signals and female mate choice criteria could be precluding premating reproductive isolation between these phenotypically “distinct” populations.

Condition-dependent chemosignals in reproductive behavior of lizards

“…Therefore, interspecific variations in composition might also reflect different climatic conditions and, furthermore, variation is also expected between populations within the same species if they live in different environmental conditions. These interpopulational differences in secretions have been found in several lizards, which is important because sexual chemosignals are often used in conspecific recognition, and, if differences between populations are large enough, they could lead to a lack of recognition, reproductive isolation and speciation (Gabirot et al, 2010a(Gabirot et al, , 2010b(Gabirot et al, , 2012a(Gabirot et al, , 2012b(Gabirot et al, , 2013Khannoon et al, 2013;Labra, 2011;Martín and López, 2006c;Martín et al, 2013c). However, we have no yet precise knowledge of whether interpopulational variations in chemosignals are relevant for speciation processes in lizards.…”

Dorsal pattern polymorphism in female Iberian wall lizards: differences in morphology, dorsal coloration, immune response, and reproductive investment

“…The highland population is located at the upper part of 'Fuenfr ıa' Valley (40°47 0 N, 04°03 0 W; 1750 m a.s.l.). Details on interpopulational differences in environmental characteristics and morphology of adult lizards are provided in Gabirot, L opez & Mart ın (2013a). It is worth noting that the P. hispanicus populations in this geographical area have just been named as a separate species within this complex (Podarcis guadarramae guadarramae; Geniez et al, 2014).…”

Environmental conditions shape the chemical signal design of lizards

“…Males of most lizard species are equipped with a series of epidermal glands located in the dermis of the inner thighs, which secrete waxy substances through pore‐bearing scales (Figure ), or ‘epidermal (femoral) pores’ (Mayerl, Baeckens, & Van Damme, ). The lipophilic compounds within the epidermal gland secretions are generally considered to be the leading source of chemical signals involved in lizard communication, and mediate behaviour in a variety of contexts (reviewed by Martín & López, ; Mayerl et al., ; but see Alberts, Phillips, & Werner, ), such as territory demarcation and assessment (Aragón, López, & Martín, ; Font, Barbosa, Sampedro, & Carazo, ; Leu, Jackson, Roddick, & Bull, ; Martín & López, ; Martins, Ord, Slaven, Wright, & Housworth, ), male rival assessment (Carazo, Font, & Desfilis, ; Hews, Date, Hara, & Castellano, ; Khannoon et al., ; López & Martín, ), female choice (Carazo, Font, & Desfilis, ; Gabirot, López, & Martín, ; Kopena, López, & Martín, ; Kopena et al., ; Martín & López, , ), assessment of female reproductive status (Cooper & Pèrez‐Mellado, ; Thomas, ), individual recognition (Alberts, ; Alberts & Werner, ; Gabirot, Castilla, López, & Martín, , ), sex identification (Cooper & Steele, ; Cooper & Trauth, ; Khannoon, Breithaupt, El‐Gendy, & Hardege, ) and species recognition (Barbosa, Font, Desfilis, & Carretero, ; Gabirot et al., ; Labra, ). Lizards passively mark or deposit these gland secretions into the environment while moving through their habitat, or they exhibit active marking behaviour to leave scent‐marks on the substrate of their choice (de Villiers, Flemming, Mouton, & Le, ; Mason & Parker, ).…”