Polyphyly of Tomopterna (Amphibia: Ranidae) based on sequences of the mitochondrial 16S and 12S rRNA genes, and ecological biogeography of Malagasy relict amphibian groups

Frog s currentl y attribute d t o th e rani d genu s Tomopterna ar e know n from sub-sahara n Africa , souther n Asi a an d Madagascar . Molecula r studie s o f mitochondria l 12 S rRN A an d 16 S rRN A gen e sequence s indicat e tha t eac h o f thes e geographi c cluster s ar e mor e closel y relate d t o othe r locall y occurrin g anura n tax a tha n the y ar e t o eac h other . Th e Malagas y T. labrosa (hithert o subgenu s Laliostoma) belong s t o a monophyleti c grou p includin g Aglyptodactylus, Boophis, an d th e mantellines ; th e souther n Asia n specie s (hithert o subgenu s Sphaerotheca) appea r t o b e relate d t o ranid s o f th e genu s Limnonectes (subgenu s Feyervarya); an d mos t surprisingly , th e Africa n specie s clustere d wit h cacosternin e ranids . Thes e result s sugges t tha t th e Asia n Sphaerotheca an d th e Malagas y Laliostoma shoul d b e raise d t o generi c rank . A s a consequence , th e distributio n patter n o f Tomopterna ar e no t informativ e regardin g continenta l drif t an d biogeographi c Madagascar-Indi a relationships . Phylogeneti c dat a o n Malagas y anuran s indicat e tha t ol d evolutionar y lineage s an d relic t form s (e . g. , Laliostoma, Aglyptodactylus, Scaphiophryne) bree d mainl y i n lenti c waterbodies , an d ofte n occu r i n savanna h habitats . I n Boophis an d mantellines , evidenc e exist s tha t th e mos t basa l group s ar e rathe r generalize d pon d breeders , wherea s th e specios e group s o f fores t broo k breeder s ma y b e monophyleti c group s partl y o f mor e recen t origin . I f corroborate d b y furthe r evidence , thi s tren d woul d indicat e a n originall y relativel y dr y an d ope n habita t typ e i n Madagasca r a t th e tim e o f differentiatio n o f th e mai n lineage s o f Malagas y anurans , whic h ma y hav e take n plac e i n th e lat e Mesozoi c o r earl y Cenozo

Exploring the potential of life-history key innovation : brook breeding in the radiation of the Malagasy treefrog genus Boophis

The treefrog genus Boophis is one of the most species-rich endemic amphibian groups of Madagascar. It consists of species specialized to breeding in brooks (48 species) and ponds (10 species). We reconstructed the phylogeny of Boophis using 16S ribosomal DNA sequences (558 bp) from 27 species. Brook-breeders were monophyletic and probably derived from an ancestral pond-breeding lineage. Pond-breeders were paraphyletic. The disparity in diversification among pond-breeders and brook-breeders was notable among endemic Malagasy frogs, although it was not significant when considering Boophis alone. Sibling species which have different advertisement calls but are virtually indistinguishable by morphology were common among brook-breeders; genetic divergence between these species was high (modal 8% total pairwise divergence). Substitution rates in brook-breeding species were significantly higher than in pond-breeders. Speciation of pond-breeders may be hindered by their usually more synchronous reproduction and a higher vagility which enhances gene flow, while a higher potential of spatial segregation and speciation may exist along brooks

Multiple overseas dispersal in amphibians.

Amphibians are thought to be unable to disperse over ocean barriers because they do not tolerate the osmotic stress of salt water. Their distribution patterns have therefore generally been explained by vicariance biogeography. Here, we present compelling evidence for overseas dispersal of frogs in the Indian Ocean region based on the discovery of two endemic species on Mayotte. This island belongs to the Comoro archipelago, which is entirely volcanic and surrounded by sea depths of more than 3500 m. This constitutes the first observation of endemic amphibians on oceanic islands that did not have any past physical contact to other land masses. The two species of frogs had previously been thought to be nonendemic and introduced from Madagascar, but clearly represent new species based on their morphological and genetic differentiation. They belong to the genera Mantidactylus and Boophis in the family Mantellidae that is otherwise restricted to Madagascar, and are distinguished by morphology and mitochondrial and nuclear DNA sequences from mantellid species occurring in Madagascar. This discovery permits us to update and test molecular clocks for frogs distributed in this region. The new calibrations are in agreement with previous rate estimates and indicate two further Cenozoic transmarine dispersal events that had previously been interpreted as vicariance: hyperoliid frogs from Africa to Madagascar (Heterixalus) and from Madagascar to the Seychelles islands (Tachycnemis). Our results provide the strongest evidence so far that overseas dispersal of amphibians exists and is no rare exception, although vicariance certainly retains much of its importance in explaining amphibian biogeography