Widespread unidirectional transfer of mitochondrial DNA: a case in western Palaearctic water frogs

Abstract

Interspecies transfer of mitochondrial (mt) DNA is a common phenomenon in plants, invertebrates and vertebrates, normally linked with hybridization of closely related species in zones of sympatry or parapatry. In central Europe, in an area north of 48°N latitude and between 8° and 22°E longitude, western Palaearctic water frogs show massive unidirectional introgression of mtDNA: 33.7% of 407 Rana ridibunda possessed mtDNA specific for Rana lessonae. By contrast, no R. lessonae with R. ridibunda mtDNA was observed. That R. ridibunda with introgressed mitochondrial genomes were found exclusively within the range of the hybrid Rana esculenta and that most hybrids had lessonae mtDNA (90.4% of 335 individuals investigated) is evidence that R. esculenta serves as a vehicle for transfer of lessonae mtDNA into R. ridibunda. Such introgression has occurred several times independently. The abundance and wide distribution of individuals with introgressed mitochondrial genomes show that R. lessonae mt genomes work successfully in a R. ridibunda chromosomal background despite their high sequence divergence from R. ridibunda mtDNAs (14.2–15.2% in the ND2/ND3 genes). Greater effectiveness of enzymes encoded by R. lessonae mtDNA may be advantageous to individuals of R. ridibunda and probably R. esculenta in the northern parts of their ranges.

Features of the karyotypes of Pelophylax ridibundus Pallas, 1771 and Rana macrocnemis Boulenger, 1885 (Amphibia: Ranidae) from Armenia

“…Thus, now in Russia and Ukraine P. ridibundus is described (Ananjeva et al, 1998), in Eastern Turkey -P. caralitanus (= R. caralitana) Arikan, 1988(Plötner, 2005Ayaz et al, 2006) (Plötner, 2005;Plötner et al, 2008).…”

“…Comparison of chromosome sets of lake frogs in Armenia (P. ridibundus) and Europe (R. fortis) (Schmid, 1978;Mészarós, Bartos, 1978;Bucci et al, 1990;Spasič-Bošković et al, 1999;Plötner, 2005;Plötner et al, 2008) reveals the differences in the number of chromosomal pairs and C-banding patterns localization, which can be explained as interspecifi c.…”

“…Presently, P. ridibundus is considered as a complex of species, based on molecular, genetic (Beerli, 1994;Beerli et al, 1996;Plötner et al, 2008) and bioacoustic (Joermann et al, 1988;Schneider et al, 1992;Schneider, Sinsch, 1992 data. Karyotypes of species of the P. ridibundus complex have been studied from the populations of Western and Central Europe (Schmid, 1978;Mészarós, Bartos, 1978;Bucci et al, 1990;Spasić-Bošković et al, 1999), Greece (Tunner, Heppich, 1982), Ukraine (Suryadnaya, 2003), Russia (Birstein, 198l;Kaibeleva et al, 2004), Turkey (Alpagut, Falakali, 1995), China (Gang Wei et al, 1992) and Saudi Arabia (Al-Shehri, Al-Salech, 2005).…”

Genetic and Genomic Interactions of Animals with Different Ploidy Levels

“…More gene flow was observed from P. perezi into P. ridibundus than from P. ridibundus into P. prezi [Schmeller et al, 2005]. P. ridibundus likely derives a selective advantage and is able to increase its distributional range by incorporating mtDNA [Plötner et al, 2008] and nuclear genes [Schmeller et al, 2005] from other species via hybridogens. In order for gene flow to occur between the species through a hybridogen, there must be some intergenomic recombination .…”

“…There is evidence that hybridogenesis can be a pathway for selective gene exchange between species through diploid hybridogenetic individuals. mtDNA of P. lessonae was found to have introgressed into several populations of P. ridibundus , but mtDNA of P. ridibundus was not found in P. lessonae [Plötner et al, 2008]. Using allozymes, Schmeller et al [2005] demonstrated that alleles can be exchanged between P. ridibundus and P. perezi through their hybridogen, P. grafi .…”