Go east: phylogeographies of Mauremys caspica and M. rivulata– discordance of morphology, mitochondrial and nuclear genomic markers and rare hybridization

Abstract

In recent years many cases of hybridization and introgression became known for chelonians, requiring a better understanding of their speciation mechanisms. Phylogeographic investigations offer basic data for this challenge. We use the sister species Mauremys caspica and M. rivulata, the most abundant terrapins in the Near and Middle East and South‐east Europe, as model. Their phylogeographies provide evidence that speciation of chelonians fits the allopatric speciation model, with both species being in the parapatric phase of speciation, and that intrinsic isolation mechanisms are developed during speciation. Hybridization between M. caspica and M. rivulata is very rare, suggesting that the increasing numbers of hybrids in other species are caused by human impact on environment (breakdown of ecological isolation). Genetic differentiation within M. caspica and M. rivulata resembles the paradigm of southern genetic richness and northern purity of European biota. However, in west Asia this pattern is likely to reflect dispersal and vicariance events older than the Holocene. For M. caspica three distinct Pleistocene refuges are postulated (Central Anatolia, south coast of Caspian Sea, Gulf of Persia). Morphologically defined subspecies within M. caspica are not supported by genetic data. This is one of the few studies available about the phylogeography of west and central Asian species.

Conservation genetics and phylogeography of the poorly known Middle Eastern terrapin Mauremys caspica (Testudines: Geoemydidae)

“…In addition, the mitochondrial cyt b gene was sequenced in cases where the data for the same samples were not available from a previous study (Fritz et al 2008). The respective mtDNA fragment was amplified for 43 samples (Table S1) using the primer pair CytbG (Spinks et al 2004) and mt-f-na (Fritz et al 2006).…”

“…The resulting mtDNA fragments had a length of approximately 1,040 bp. Individual sequences were aligned in BIOEDIT 7.0.5.3 (Hall 1999), collapsed manually into haplotypes and merged with previously published data (see Fritz et al 2008 for GenBank accession numbers).…”

“…A first phylogeographic investigation using the mitochondrial cytochrome b (cyt b) and the nuclear C-mos genes found only weak differentiation, with two mitochondrial haplotype clusters, one occurring in the east and the other in the west of the range (Fritz et al 2008). This study did not shed light on the possible non-native status of the Arabian populations, even though a high diversity of mitochondrial haplotypes was recorded for Bahrain.…”

Red- and yellow-footed tortoises, Chelonoidis carbonaria and C. denticulata (Reptilia: Testudines: Testudinidae), in South American savannahs and forests: do their phylogeographies reflect distinct habitats?

“…Therefore, here we use sequence variation in the mitochondrial cytochrome b (cyt b) gene, a phylogeographically highly informative marker in chelonians (e.g. Caccone et al 1999;Fritz et al 2005Fritz et al , 2006Fritz et al , 2008Fritz et al , 2009aLenk et al 1999), to examine C. carbonaria and C. denticulata. Furthermore, based on relaxed molecular clock analyses, we estimate for the savannah species C. carbonaria the approximate dates of population divergence.…”

Fifteen microsatellite markers for the stripe-necked terrapin Mauremys caspica (Testudines: Geoemydidae) and cross-amplification tests in M. rivulata

“…Along their distribution margins, hybridization occurs, but is very rare. The two species offer an attractive model for studying differentiation processes and gene flow during the parapatric phase of allopatric speciation (Fritz et al 2008). New microsatellite primers were designed for assessing gene flow, population differentiation and the level of reproductive isolation of the two species.…”