Microgeographical Variations in Coloration of Male Iberian Wall Lizards May Be Related to Habitat and Climatic Conditions

Intraspecific variations in coloration may represent a compromise between selection for intraspecific communication and selection for thermoregulation and predator avoidance. Iberian wall lizards, Podarcis hispanica, exhibit substantial levels of intraspecific variation that cannot be necessarily attributed to genetic differences. We compared variations in coloration and habitat use of three phenotypically distinct populations of P. hispanica in Central Spain. Results suggested that differences in coloration may be related to habitat characteristics and climatic conditions. Thus, lizards from populations with colder temperatures were darker and larger, which may favor thermoregulation. Lizards that lived in habitats with more vegetation and darker granite rocks showed a dark brown to black dorsal coloration. In contrast, lizards from habitats with gypsum and light sandy soil without vegetation or large rocks had a brighter yellow to green dorsal coloration. These differences may increase crypsis to predators in each habitat. There were also differences in the characteristics and relative importance of sexual visual signals (i.e., ventrolateral coloration and number of lateral blue spots) and chemical signals (i.e., number of femoral pores) that might increase efficiency of communication in each environment. Natural selection for traits that allow a better thermoregulation, predator avoidance, and communication might lead to population divergence.

Iridovirus-Like Viruses in Erythrocytes of Lacertids from Portugal

Icosahedral nucleo-cytoplasmic large DNA viruses (NCLDV)-like viruses, which form inclusions in the erythrocyte cytoplasm of reptiles, were previously presented as candidates for a new genus of theIridoviridaefamily. The present work describes the distribution of infected lizard hosts and ultrastructural characteristics of the viral inclusions of NCLDV-like viruses from Portugal and adjacent locations in Spain. Giemsa-stained blood smears of 235Lacerta schreiberifrom Portugal and Spain, 571Lacerta monticolafrom the mountain Serra da Estrela (Portugal), 794Podarcis hispanicafrom several localities in Portugal and Spain, and 25Lacerta dugesiifrom Madeira Island, were studied. Infection inL. schreiberiwas only found in mountain populations, up to 30% in Serra da Estrela and 9–11% elsewhere. It was absent in lizards from lowlands. Prevalence of infection amongL. monticolain Serra da Estrela was 10%; infected lizards were found during March to July and October but not in August and September. Infection inP. hispanicawas below 3.3%. Only one infected specimen ofL. dugesiiwas identified by light microscopy. Ultrastructural examination of infected samples revealed that the inclusions are virus assembly sites of icosahedral cytoplasmic iridovirus-like virions. Virions from different host species have different ultrastructural features and probably represent different related viruses.

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

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.

Differences in Chemical Sexual Signals May Promote Reproductive Isolation and Cryptic Speciation between Iberian Wall Lizard Populations

Interpopulational variation in sexual signals may lead to premating reproductive isolation and speciation. Genetic and morphological studies suggest that the Iberian wall lizard, Podarcis hispanica, forms part of a “species complex” with several cryptic species. We explored the role of chemical sexual signals in interpopulational recognition between five distinct populations of Iberian wall lizards in Central Spain. Results showed that these populations differed in morphology and in composition and proportion of chemical compounds in femoral gland secretions of males. Tongue-flick experiments indicated that male and female lizards discriminated and were more interested in scents of lizards from their own area (i.e., Northern versus Southern populations), but did not discriminate between all populations. Moreover, only males from the populations that are geographically located more far away preferred scent of females from their own population. These data suggest that, at least between some populations, there may be reproductive isolation mediated by chemical signals and cryptic speciation.

Chemosensory species recognition may reduce the frequency of hybridization between native and introduced lizards

The introduction of alien species to islands by human activity can cause catastrophic consequences for small populations of island endemics. Hybridization between the endangered and endemic insular lizard Podarcis atrata (Boscá, 1916) from the Columbretes Islands (Mediterranean, Spain) and the common mainland lizard Podarcis hispanica (Steindachner, 1870) could potentially occur because mainland haplotypes have already been detected in the islands, the two species are closely genetically related, and the frequency of visitors to these islands is increasing. However, reproductive decisions of lizards are often mediated by species recognition mechanisms based on chemical cues. On the basis of this observation, even if some mainland P. hispanica lizards were introduced to the islands, interspecific recognition might make rare an eventual hybridization with the insular P. atrata. We examined interspecific chemical recognition between the insular P. atrata and the mainland P. hispanica. Our results showed that lizards of both sexes responded more strongly (i.e., directed a significantly higher number of tongue flicks) to scents of conspecific individuals than to scents of heterospecifics. Chemical recognition of conspecifics by endemic island P. atrata lizards may reduce the occurrence of hybridization with introduced mainland P. hispanica lizards and protect the insular gene pool.