Assessment of the Endangered Species Podarcis carbonelli on a Microgeographic Scale: A Molecular, Morphological and Physiological Approach
The lizard Podarcis carbonelli is an endangered species endemic to the Iberian Peninsula. One location where this species occurs is at the Berlengas Natural Preserve, an Atlantic archipelago off the coast of Portugal. These island populations are geographically separated from nearby mainland populations. The fundamental question is, are these insular individuals distinct from the mainland populations? Four localities were chose for comparison: two island populations and two nearby coastal populations. We assessed this question using three distinct approaches: molecular, morphological and physiological approach. We sequenced the 12S RNA, the mtDNA Control Region and the 7th intron of the !-fibrinogen gene and determined genetic diversity values as well as several parameters of population structure and differentiation. Individuals from these populations were also measured for several biometric characters and their blood lactate concentration was sampled. There was no genetic variation in both the mtDNA regions analyzed. The nuclear intron revealed high levels of genetic variation, with islands having in general lower values than the mainland regions. The four populations sampled had low levels of divergence; the populations of Berlenga and Peniche were the most distinct and the populations of Farilhão and Baleal were the most similar from the four populations sampled. Morphometric analyses revealed a different pattern of similarity among populations with the population of Farilhão being the only population statistically distinct from all other populations based on mass and SVL. Furthermore, island populations were in general more similar to each other than to mainland populations, with the exception of Berlenga males which in size are more similar to the Peniche males. The analysis of the blood lactate concentration revealed that the population of Peniche has significantly lower blood lactate levels than the populations of Farilhão and Berlenga. The lack of genetic differentiation found in the populations under study is most likely due to the recent divergence of these populations. Furthermore, the genetically most different populations (Berlenga and Peniche) are not the most distinct in terms of morphology, particularly the males. This suggests that genetic drift, the most likely mechanism behind the genetic differentiation seen, is not responsible for the morphological differences observed. The morphological differences seen can be attributed to: a possible difference in age of the individuals in each population; mechanisms of natural selection that are favoring specific phenotypes in each of the populations, or phenotypic plasticity. The differences in blood lactate levels found between the population of Peniche and the island populations can be attributed to differences in predatory pressure or home range size. It is suggested that the island populations are closely monitored due to their likely isolation, low mtDNA diversity and possible higher predatory pressure than initially predicted.
Kentucky Academy of Sciences, lizards, morphology, mitochondrial DNA sequence, Biology, Cell Biology, Ecology and Evolutionary Biology, Molecular Genetics, Terrestrial and Aquatic Ecology
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