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Multilocus genetic diversity and historical biogeography of the endemic wall lizard from I biza and F ormentera, P odarcis pityusensis ( S quamata: L acertidae)
Author(s) -
Rodríguez V.,
Brown R. P.,
Terrasa B.,
PérezMellado V.,
Castro J. A.,
Picornell A.,
Ramon M. M.
Publication year - 2013
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.12443
Subject(s) - biology , phylogeography , coalescent theory , genetic divergence , genetic diversity , squamata , ecology , zoology , evolutionary biology , phylogenetics , population , genetics , demography , sociology , gene
Two monophyletic sister species of wall lizards inhabit the two main groups of B alearic I slands: P odarcis lilfordi from islets and small islands around M allorca and M enorca and P odarcis pityusensis from I biza, F ormentera and associated islets. Genetic diversity within the endangered P . lilfordi has been well characterized, but P . pityusensis has not been studied in depth. Here, 2430 bp of mt DNA and 15 microsatellite loci were analysed from P . pityusensis populations from across its natural range. Two main genetic groupings were identified, although geographical structuring differed slightly between the mt DNA and the nuclear loci. In general, individuals from islets/islands adjacent to the main island of I biza were genetically distinct from those from F ormentera and the associated F reus islands for both mt DNA and the nuclear loci. However, most individuals from the island of I biza were grouped with neighbouring islets/islands for nuclear loci, but with F ormentera and F reus islands for the mitochondrial locus. A time‐calibrated B ayesian tree was constructed for the principal mitochondrial lineages within the B alearics, using the multispecies coalescent model, and provided statistical support for divergence of the two main P . pityusensis lineages 0.111–0.295 Ma. This suggests a mid‐late P leistocene intraspecific divergence, compared with an early P leistocene divergence in P . lilfordi , and postdates some major increases in sea level between 0.4 and 0.6 Ma, which may have flooded F ormentera. The program IM a2 provided a posterior divergence time of 0.089–0.221 Ma, which was similar to the multispecies coalescent tree estimate. More significantly, it indicated low but asymmetric effective gene copy migration rates, with higher migration from F ormentera to I biza populations. Our findings suggest that much of the present‐day diversity may have originated from a late P leistocene colonization of one island group from the other, followed by allopatric divergence of these populations. Subsequent gene flow between these insular groups seems likely to be explained by recent human introductions. Two evolutionary significant units can be defined for P . pityusensis but these units would need to exclude the populations that have been the subjects of recent admixture.