Quaternary History of an Endemic Passerine Bird on Corsica Island: Glacial Refugium and Impact of Recent Forest Regression

Abstract

Molecular studies support the hypothesis that Corsica Island was a glacial refugium for a number of forest birds during the Pleistocene. We focused on the Corsican nuthatch (Sitta whiteheadi), an endemic passerine strongly associated with the laricio pine (Pinus nigra laricio). The range of laricio pine has been impacted by the Pleistocene glacial periods and forest has been recently fragmented by cutting and fires. Using both molecular (mitochondrial and nuclear) and morphological characters, we assessed the variation within the nuthatch population. Our results are consistent with the hypothesis that the Corsican nuthatch endured through the late Pleistocene and Holocene climatic variations, and sustained the subsequent cycles of forests reduction/expansion. The results also suggest that the recent anthropization of the landscape resulted in the isolation of a cluster of populations in the northern part of the island. The fragmentation of the habitat of the nuthatch may impede the future of the bird by creating isolated population units between which the gene flow is reduced.

Gene flow and genetic divergence among mainland and insular populations across the south-western range of the Eurasian treecreeper (Certhia familiaris, Aves)

“…We did not detect any significant genetic structure within Corsica for the Eurasian treecreeper; this situation is in contrast with what has been found for Sitta whiteheadi (Thibault et al, 2016), another forested passerine endemic to Corsica. Such a difference between both species might be explained by their distinctive habitat requirements, the Corsican nuthatch occurring only in mature scattered forested patches of Pinus nigra laricio (Thibault et al, 2016) whereas the Eurasian treecreeper occupies a larger variety of tree species and is more continuously distributed over Corsica, although still in mature forests (Thibault et al, unpublished results); moreover, birds regularly disperse outside their breeding range into secondary habitats.…”

Digging up the roots of an insular hotspot of genetic diversity: decoupled mito-nuclear histories in the evolution of the Corsican-Sardinian endemic lizard Podarcis tiliguerta

“…Thus, these preliminary findings point to the interesting possibility that local adaptation leading to phylogeographic structure could influence both mitochondrial genes and nuclear genes functionally related to mitochondrial genes. This line of research appears particularly promising on Corsican Sardinian endemics for several reasons: (i) the well delimited and restricted spatial scale of this insular setting [ 19 ]; (ii) the availability of previous phylogeographic assessment and well known distribution of the species [ 12 , 13 , 20 – 34 ]; (iii) the growing number of cases of deep within-islands mitochondrial divergence that has been observed in the absence of a current or historical barrier to gene flow [ 12 , 13 , 29 ]; this study]; and (iv) preliminary evidence of association of allozyme genetic variation with climatic variables [ 21 , 27 ]. Thus, Corsican-Sardinian endemic lizards appear a promising model for testing how and whether selection has been shaping patterns of within-species diversity in such a biodiversity hotspot.…”

“…In the last decade, Corsican-Sardinian species have been the subject of intensive phylogeographic surveys, especially regarding amphibians and reptiles [ 12 , 13 , 20 – 34 ], which have revealed how an essential component of the Tyrrhenian biodiversity hotspot is represented by the genetic variation held within and among populations of these endemic species. A significant realization of these studies is that the current patterns of genetic structure and diversity of these endemic species have been historically shaped by an unexpectedly diverse array of evolutionary and demographic processes acting across unrelated spatial and temporal scales [ 20 ].…”

Evolutionary and demographic correlates of Pleistocene coastline changes in the Sicilian wall lizardPodarcis wagleriana

“…The Mediterranean Basin is a global biodiversity hotspot (Myers, Mittermeier, Mittermeier, Da Fonseca, & Kent, 2000), with a large proportion of species richness and endemism being hosted within southern peninsulas and islands (Kier et al, 2009). Recent phylogeographic studies on Mediterranean island endemics, for example on amphibian and reptiles of Western Mediterranean islands, have revealed responses to past climatic oscillations with a complexity of population structures and evolutionary histories comparable to that observed for continental species Bisconti, Canestrelli, Salvi, & Nascetti, 2013;Ketmaier & Caccone, 2013;Ketmaier, Manganelli, Tiedemann, & Giusti, 2010;Salvi, Bisconti, & Canestrelli, 2016;Salvi, Harris, Bombi, Carretero, & Bologna, 2010;Salvi, Pinho, & Harris, 2017;Thibault, Cibois, Prodon, & Pasquet, 2016). These encompass movement of species across land bridges exposed during glacial sea-level low stands (e.g., Bisconti et al, 2011;Rodríguez et al, 2013;Salvi, Capula, Bombi, & Bologna, 2009;Salvi, Harris, Perera, Bologna, & Carretero, 2011), secondary contacts between isolated lineages within islands (Bisconti, Canestrelli, Salvi, et al, 2013;Salvi et al, 2010) as well as spatial and demographic expansion associated with glaciation-induced increase in lowland areas during marine regression (Bisconti et al, 2011;Salvi et al, 2014).…”