Abstract
AbstractAimsTo characterize the genetic and morphological diversification of the endangered Balearic lizard Podarcis lilfordi and to assess the relevance of this diversity, and how it is described, to conservation measures.LocationThis study covers all the populations of the Balearic lizard, Podarcis lilfordi, present in its range of distribution at coastal islets of Menorca, Mallorca and Cabrera Archipelago.MethodsWe analysed genetic and morphological variation across the 43 known extant populations of the Balearic lizard, using mitochondrial and nuclear markers. We examined morphometric and scalation characters using, in some cases, phylogenetically independent contrasts. We also incorporated the study of dorsal coloration and dorsal colour pattern including the analysis of melanism in several populations.ResultsWe detected clear genetic divergence between Menorcan populations and populations from Mallorca and Cabrera, in both nuclear and mtDNA markers, but genetic divergence is relatively low among different insular populations within these groups. In contrast, morphological divergence was substantial both between Menorcan and remaining populations and within these groups. Morphological traits, such as dorsal coloration, body size and the number and size of scales, seemed to be linked with differences in climatic conditions between populations. In addition, some traits, as melanism, showed a strong phylogenetic signal.Main conclusionsThe morphological and genetic diversity of the Balearic lizard is incongruent with the subspecies described in the classical taxonomic literature. Moreover, current populations differ not only in some genetic and morphological features, but also in several ecological and ethological characteristics, in many cases unique to one population. Based on our results, we propose abandoning the use of subspecies to describe the extraordinary morphological diversity of the Balearic lizard and its replacement with the concept of evolutionary significant units (ESUs). ESUs are particularly suitable to describe and recognize such diversity and, especially, to ensure the continuity of the evolutionary process.
Highlights
For a variety of taxa, islands make a very important contribution to biodiversity, out of proportion to their land area in comparison with continents
Nuclear DNA markers are analysed for the first time, and we describe the morphometry, scalation and colour patterns of populations
The genealogical relationships between the haplotypes of the phased nuclear gene were inferred using the TCS statistical parsimony network approach (Clement, Posada, & Crandall, 2000) with 95% connection limit implemented in the program popart 1.7
Summary
For a variety of taxa, islands make a very important contribution to biodiversity, out of proportion to their land area in comparison with continents. During the Holocene, around 2,000 years ago, the species became extinct on the main islands of Mallorca and Menorca, probably as a consequence of the introduction of terrestrial predators by Romans (Pérez-Mellado, 2009 and references therein). It survives only on the small islets found around the coasts of Menorca and Mallorca, together with Cabrera archipelago and a small introduced population in Colonia Sant Jordi, in Southern Mallorca (Figure 1). Population studied from the Bay of Palma (Mallorca), at Porrassa Islet, is known to have been introduced, as well as the small population of Colonia de Sant Jordi in Southern Mallorca
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