Intraspecific genetic variation in the common midwife toad (Alytes obstetricans): subspecies assignment using mitochondrial and microsatellite markers

Abstract

The common midwife toad (Alytes obstetricans), widely distributed in the northern half of the Iberian Peninsula and part of Western Europe, is currently subdivided into four subspecies: A. o. obstetricans, A. o. boscai, A. o. pertinax and A. o. almogavarii. However, the delimitation of these subspecies and their ranges are still under discussion because strong discordances have been found between morphological and molecular data, and especially among different genetic markers. Here, we screen a set of novel microsatellite loci and mtDNA sequences of A. obstetricans populations representative of all currently recognized subspecies to investigate the correspondence between genetic groupings inferred from clustering analysis of microsatellite genotypes and the described subspecies and test whether patterns of mtDNA variation are concordant with those genetic clusters. Our results confirm previous expectations of extremely high intraspecific diversity in A. obstetricans in Iberia. Analyses of microsatellite and mtDNA data were concordant in recovering five well‐defined groups, of which three correspond to previously defined subspecies, while the two additional clusters correspond to populations of subspecies A. o. boscai separated by the Douro River. Our results suggest the occurrence of two distinct genetic units within A. o. boscai that likely result from a long independent evolutionary history, thus deserving special attention from a conservation point of view.

Multilocus phylogeography of the common midwife toad, Alytes obstetricans (Anura, Alytidae): Contrasting patterns of lineage diversification and genetic structure in the Iberian refugium

“…Our analysis of genetic diversity in A. obstetricans revealed very high levels of intraspecific variation in Iberia, in agreement with previous results based on allozymes (Arntzen and García-París, 1995), morphology , and mtDNA and nuclear markers (Fonseca et al, 2003;Martínez-Solano et al, 2004;Gonçalves et al, 2007;Maia-Carvalho et al, 2014a). The common midwife toad has been previously considered as including four essentially parapatric subspecies in the Iberian Peninsula (A. o. obstetricans, A. o. boscai, A. o. pertinax, and A. o. almogavarii; see Fig.…”

“…First, the location of the northern boundary between A. o. boscai and A. o. obstetricans had been inferred to be in the Pyrenees, based on allozyme data (Arntzen and Szymura, 1984), but was shown to be more likely located in the Iberian northwest, somewhere between northern Portugal and the Cantabrian Mountains. Second, Maia-Carvalho et al (2014a) revealed the existence of two well-differentiated groups within A. o. boscai, separated by the Douro River, as suggested by Fonseca et al (2003). Additionally, the recent multilocus assessment of phylogenetic relationships in Alytes by Maia-Carvalho et al (2014b) produced inconclusive results about the relationships between major clades in A. obstetricans and indicated conflict with the current morphology-based subspecific taxonomy.…”

“…While several studies have addressed patterns of variation in morphology, allozymes, and mitochondrial and nuclear DNA (Arntzen and García-París, 1995;Fonseca et al, 2003;Martínez-Solano et al, 2004;Gonçalves et al, 2007), several aspects of the evolutionary history of this species remain unsolved. Recently, a study by Maia-Carvalho et al (2014a), based on mitochondrial and microsatellite data in a set of populations representative of all currently recognized subspecies, revealed discordances with previous studies. First, the location of the northern boundary between A. o. boscai and A. o. obstetricans had been inferred to be in the Pyrenees, based on allozyme data (Arntzen and Szymura, 1984), but was shown to be more likely located in the Iberian northwest, somewhere between northern Portugal and the Cantabrian Mountains.…”

“…1). Some mitochondrial and nuclear sequences (identified in Table 1) were generated in previous genetic studies on Alytes (Gonçalves et al, 2007;Gonçalves et al, 2009;Pinho et al, 2010;Maia-Carvalho et al, 2014a, b). Newly collected tissue samples were obtained from toe tips of adults or tail tips of larvae, and preserved in 95% ethanol.…”

The evolutionary history and taxonomic reevaluation of the Japanese coral snake,Sinomicrurus japonicus(Serpentes, Elapidae), endemic to the Ryukyu Archipelago, Japan, by use of molecular and morphological analyses

“…To examine whether previously described subspecies actually represent unique evolutionary lineages, many attempts have been made using a variety of conventional and modern methods, including quantitative morphological analyses and molecular phylogenetic analyses (e.g. Glor and Laport 2012;Hawlitschek et al 2012;Maia-Carvalho et al 2014;Sackett et al 2014). Although the necessity or efficacy of the subspecies as a taxonomic rank has been repeatedly questioned (Hillis 1992;Burbrink et al 2000;Zink 2004), taxonomic studies in search of definable subspecies with multiple methods have contributed to the establishment of universal criteria of the subspecies rank (Sackett et al 2014;Torstrom et al 2014).…”