Interpopulational differences in chemical composition and chemosensory recognition of femoral gland secretions of male lizards Podarcis hispanica: implications for sexual isolation in a species complex

Abstract

Molecular studies suggest that the Iberian wall lizard, Podarcis hispanica, forms a species complex with several monophyletic types. In Central Spain two of these types are spatially not isolated and may interact. Sex pheromones are important for species recognition and, thus, differences between lizards' types in chemicals used in intraspecific communication could lead to reproductive isolation. Analyses by GC-MS showed that the femoral gland secretions of adult males of different types were different. Males of one type had twelve exclusive compounds, and proportions of some shared compounds differed. This presumably would reflect selection for the persistency and efficiency of chemical signals in different environments; less volatile compounds and with a higher chemical stability being favoured in the type of lizards inhabiting more humid climatic conditions. Differential tongue-flick rates to scents from femoral secretions indicated that males were able to detect and discriminate between males of different types based on chemical cues alone. In contrast, females detected but did not seem able to discriminate between scents of the two types of males. Thus, multiple factors might be simultaneously acting either against or in favor of speciation, leading, on the one hand, to genetic differences between types, but, on the other hand, probably precluding an effective reproductive isolation in areas where both types of lizards may interact.

Chemical Constituents of the Femoral Gland Secretions of Male Tegu Lizards (Tupinambis merianae) (Family Teiidae)

“…steroids and fatty acids) seem to be the main compounds involved in pheromonal communication (Mason, 1992;Martín and López, 2006a, 2010a, 2011. Although the types of compounds in secretions are similar in different lizard species, the presence and abundance of specifi c compounds vary widely between species (Weldon et al, 2008), which might be due to phylogenetic or environmental differences (Alberts, 1992;Escobar et al, 2003;Martín and López, 2006b). However, the chemical composition of femoral gland secretions has been analysed in only a few lizard species (reviewed in Weldon et al, 2008).…”

Lizard Epidermal Gland Secretions I: Chemical Characterization of the Femoral Gland Secretion of the Sungazer, Cordylus giganteus

“…However, the published mass spectral data of this steroid did not correspond well with the mass spectrum of constituent 46, and therefore, this compound remains unidentified. Another ten steroids could not be identified, some of which are also present and unidentified in other lizards (Martín and López 2006b). …”

Natural products from the integument of nonavian reptiles

“…Unsaturation at this site denotes compounds potentially derived from (Z)-octadecenoic (oleic) acid. 23 Methyl ketones (52,53,55,(57)(58)(59)(60)(61)(62)(63)(64)(65)) also occur in male and she-male garter snakes.…”

“…35 These ketodienes and the other methyl ketones present in this species (52)(53)(54)(55)(56)(57)(58)(59)(61)(62)(63)(64)(65), if active as pheromones, might be used to control this invasive snake. 37 Female leopard geckos possess saturated methyl ketones 55 and 57 as well as uncharacterized unsaturated analogs, but males do not.…”