Assessing the molecular phylogeny of a near extinct group of vertebrates: the Neotropical harlequin frogs (Bufonidae; Atelopus)

作者：Loetters Stefan; Van der Meijden Arie; Coloma Luis A; Boistel Renaud; Cloetens Peter; Ernst Raffael; Lehr Edgar; Veith Michael

来源：Systematics and Biodiversity, 2011, 9(1): 45-57.

DOI：10.1080/14772000.2011.557403

• Amphibia
• Atelopus
• Bufonidae
• DNA barcoding
• Osornophryne
• species groups
• systematics

Neotropical harlequin frogs, Atelopus, are a species-rich bufonid group. Atelopus monophyly has been suggested but intergeneric, interspecific and intraspecific relationships are poorly understood. One reason is that morphological characters of harlequin frogs are often difficult to interpret, making species delimitations difficult. Molecular analyses (DNA barcoding, phylogeny) may be helpful but sampling is hampered as most of the more than 100 Atelopus species have undergone severe population declines and many are possibly extinct. We processed mitochondrial DNA (12S and 16S rRNA) of 28 available ingroup samples from a large portion of the genus' geographic range (Bayesian Inference, Maximum Likelihood). Our samples constitute a monophyletic unit, which is sister to other bufonid genera studied including the Andean genus Osornophryne. In contrast to previous morphological studies, our results suggest that Osornophryne is neither sister to Atelopus nor nested within it. Within Atelopus, we note two major clades with well supported subclades, one Amazonian-Guianan Clade (Flavescens-spumarius Clade plus Tricolor Clade) and an Andean-Choco-Central American Clade (Varius Clade plus all other Atelopus). The first mentioned includes all species that possess a middle ear (i.e. stapes) except for A. seminiferus lacking it (like all remaining Atelopus). Previously proposed species groups based on frog-like versus toad-like overall appearance (i.e. Longirostris and Ignescens Groups) or phalangeal reduction in the thumb (i.e. Flavescens Group) are not monophyletic in our phylogeny, thus characters used to define them are not considered synapomorphies. We show that genetic divergence can be high between species belonging to different clades, in spite of their phenetic similarity (e.g. A. pulcher, Atelopus sp. 2). On the other hand, within the same clade, colour can vary tremendously, while genetic divergence is low (e.g. A. flavescens and allies). These observations demonstrate that Atelopus taxonomy is complicated and that an integrative approach is required before 'splitting' or 'lumping' nominal species.

• 出版日期2011