Multilocus assessment of phylogenetic relationships in Alytes (Anura, Alytidae)

With the advent of large multilocus datasets, molecular systematics is experiencing very rapid progress, but important challenges remain regarding data analysis and interpretation. Midwife toads (genus Alytes) exemplify two of the most widespread problems for accurate phylogenetic reconstruction: discerning the causes of discordance between gene trees, and resolving short internodes produced during rapid, successive splitting events. The three species in subgenus Baleaphryne ( A. maurus, A. dickhilleni and A. muletensis), the sister group to A. obstetricans, have disjunct and highly restricted geographical ranges, which are thought to result from old vicariant events affecting their common ancestor, but their phylogenetic relationships are still unresolved. In this study we re-address the phylogeny of Alytes with a special focus on the relationships in Baleaphryne with a multilocus dataset including > 9000 base pairs of mitochondrial DNA and four nuclear markers (3142. bp) in all recognized taxa, including all subspecies of A. obstetricans. Both concatenation and species tree analyses suggest that A. muletensis, endemic to the Balearic island of Mallorca, is the sister taxon to a clade comprising the southeastern Iberian endemic A. dickhilleni and the North African A. maurus. This scenario is consistent with palaeogeological evidence associated with the fragmentation of the Betic-Rifean Massif, followed by the opening of the Strait of Gibraltar. On the other hand, analyses of intraspecific variation in A. obstetricans are inconclusive regarding relationships between major clades and conflict with current subspecific taxonomy.This work was supported through Project “Genomics and Evolutionary Biology” cofinanced by North Portugal Regional Operational Programme 2007/2013 (ON.2 – O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF); the Program Operacional Factores de Competitividade (COMPETE), and by national funds from Fundação para a Ciência e a Tecnologia (FCT), through the research Project PTDC/BIA-BEC/099915/2008 to HG; and partial funds provided by grants CGL2008-04271-C02-01/BOS and CGL2011-28300 (Ministerio de Ciencia e Innovación, Ministerio de Economía y Competitividad, Spain, and FEDER) and PPII10-0097- 4200 (Junta de Comunidades de Castilla la Mancha and FEDER) to IMS, who is currently funded by Project “Biodiversity, Ecology and Global Change”, co-financed by North Portugal Regional Operational Programme 2007/2013 (ON.2 – O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF). BMC is supported by a PhD grant from FCT (SFRH/BD/60305/2009), and HG is supported by a postdoctoral grant from FCT (SFRH/BPD/26555/2006).Peer Reviewe