A combination of long term fragmentation and glacial persistence drove the evolutionary history of the Italian wall lizard Podarcis siculus

Abstract

BackgroundThe current distribution of genetic diversity is the result of a vast array of microevolutionary processes, including short-term demographic and ecological mechanisms and long-term allopatric isolation in response to Quaternary climatic fluctuations. We investigated past processes that drove the population differentiation and spatial genetic distribution of the Italian wall lizard Podarcis siculus by means of sequences of mitochondrial cytb (n = 277 from 115 localities) and nuclear mc1r and β-fibint7genes (n = 262 and n = 91, respectively) from all its distribution range. The pattern emerging from the genetic data was compared with current and past (last glacial maximum) species distribution modeling (SDM).ResultsWe identified seven deeply divergent parapatric clades which presumably remained isolated in different refugia scattered mainly throughout the Tyrrhenian coast. Conversely, the Adriatic coast showed only two haplogroups with low genetic variability. These results appear to agree with the SDM prediction at the last glacial maximum (LGM) indicating a narrow area of habitat suitability along the Tyrrhenian coast and much lower suitability along the Adriatic one. However, the considerable land exposure of the Adriatic coastline favored a glacial colonization of the Balkan Peninsula.ConclusionsOur population-level historical demography showed a common trend consistent with glacial expansions and regional persistence during the last glacial maximum. This complex genetic signature appears to be inconsistent with the expectation of the expansion-contraction model and post-LGM (re)colonizations from southern refugia. Hence it is one of an increasing number of cases in which these assumptions are not met, indicating that long-term fragmentation and pre-LGM events such as glacial persistence were more prominent in shaping genetic variation in this temperate species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0847-1) contains supplementary material, which is available to authorized users.

Mammal endemism In Italy: A review

“…Older species result to be the soricomorph Sorex samniticus and Talpa romana, and the two insular endemics: the bat Plecotus sardus and the soricomorph Crocidura sicula. It should be considered that the southernmost part of Italy, including Sicily and Sardinia, constitute for some xerophilic species a particular favorable area not only during interglacials but even during glacial maxima when a strong sea level decrease occurred (as much as 120-135 m) leading to the increase of the Mediterranean coastal plains and favoring the formation of new suitable habitats with consequent population expansions (Bisconti et al 2011;Senczuk et al 2017). This could have allowed the survival of some old mammal endemic species as well as for other paleoendemic vertebrates across different climatic oscillations in those southern areas of the country.…”

A review of phylogeography: biotic and abiotic factors

“…The important feature of plant dispersal is that we can notice whether genes are distributed through dispersal of seed or pollen. This distinction allows us to identify whether environmental components, i.e., phonological differences could affect differential fertilization success between populations and biotic dispersal vectors (Sork et al, 2016). Plants have chloroplast which is haploid and non-recombinant that are important for documentation of migration, and history of population structure.…”

“…Results indicated that warmer conditions of the last interglacial-induced population contraction. The phylogeography of Podarcis siculus was studied using mitochondrial cyt b, nuclear mc1r and β-fibint 7 genes (Senczuk, Colangelo, De Simone, Aloise, & Castiglia, 2017). The population level historical demography showed a trend constant with glacial expansion and regional determination during the last glacial maximum.…”

“…Because of the restricted and fragmented dispersal of Pinus longaeva, its level of genetic diversity is similar to that of other pines. However, we see various tree species with global distribution whose longevity may checked population contractions from resulting in complete extinction before environmental factors would allow expansion (Sork et al, 2016). Questel, Blanco-Bercial, Hopcroft, and Bucklin (2016) studied the gene movement in genus Pseudocalanus from Eastern North Pacific and the Pacific Arctic region.…”

“…Phylogeography certifies the spatial dispersal of genetic lineages that results due to population expansion, population contraction and gene movements. Most of the phylogeographic studies used neutral markers, however not too much emphasis is given to the role of selection in phylogeography (Sork et al, 2016). Wiantoro, Maryanto, and Abdullah (2012) studied the phylogeography of Myotis muricola from west and east of Wallace's line using partial mitochondrial DNA cyt b gene and concluded that species exhibit some degree of population structure that can be analyzed in geographic and sequential contexts.…”