Phylogeny and biogeography of midwife toads (Alytes, Discoglossidae): a reappraisal

The allozyme data base of Arntzen & García-París (1995) on midwife toads (Alytes, Discoglossidae) is reanalysed considering each locus as a discrete character. The phylogeny thus inferred differs from the one obtained with genetic distances in the position of A. dickhilleni from the Betic region – it appears that its sister species is the widespread A. obstetricans, not the Mallorcan endemic A. muletensis. This phylogenetic hypothesis agrees with the taxonomic treatment of the genus based on morphology. A testable biogeographic hypothesis is proposed to account for the diversification of midwife toads in Iberia and the Balearics. The postulated underlying geological changes were the spread of inland saline lakes that divided Iberia (16 mY B.P.), the emergence and break-up of the Betic orogen (14 mY), and the formation of the Betic Strait (8 mY). Dispersal over sea channels or during the Messinian Crisis (6 mY) are deemed unlikely on the basis of ecological and biogeographical data.