Mantellid frogs present an extensive adaptive radiation endemic to Madagascar and Comoros, being the subfamily Mantellinae the most morphologically and ecologically diverse. The Mantellinae present key innovative evolutionary traits linked to their unique reproductive behavior, including the presence of femoral glands and a derived vomeronasal organ. In addition, previous studies pointed to size differentiation in playing an important role in species’ dispersal capacities and shaping of their geographic ranges. Despite the high phenotypic variation observed in this clade, to date an exhaustive morphological analysis of their anatomy has still not been performed, much less in relation to internal structures. Here, we present a comprehensive skeletal description of a mantellid species, Blommersia transmarina, from the island of Mayotte in the Indian Ocean, which has potentially undergone a process of moderate gigantism compared to other Blommersia species. We describe its intraspecific skeletal variation utilizing non-destructive volume renderings from μCT-scans, and characterize the presence of sexual dimorphism and size covariation in skeletal structures. Notably, we found numerous signs of hyperossification, a novel structure for mantellids: the clavicular process, and the presence of several appendicular sesamoids. Our findings suggest that skeletal phenotypic variation in this genus may be linked to biomechanical function for reproduction and locomotion.
Pyxis arachnoides is a Critically Endangered Malagasy tortoise for which little data about its natural history and genetic variation are available. This lack of knowledge complicates undertaking conservation measures considering Pyxis genetic diversity. Here, we describe six new microsatellites for Pyxis arachnoides from wild specimens and several localities, and the cross amplification of two Astrochelys radiata microsatellites. Of these microsatellites, two are monomorphic among the three distinct subspecies and a closely related species, while the remaining six are polymorphic. Microsatellite data are needed for this species to study the inter- and intra-subspecies genetic diversity, especially for the highly endangered subspecies P. a. brygooi, which currently occurs only in remote localities. The availability of polymorphic microsatellites will allow identifying the population of origin of individuals and will aid in justifying their management as separate evolutionary lineages for conservation purposes. The rationale is to preserve both evolutionary processes and adaptive potential.
Next Generation Sequencing (NGS) and related technologies have revolutionized the field of conservation and population genetics, providing novel tools and the capacity to discover thousands of new Single Nucleotide Polymorphisms (SNPs) for the analysis of population parameters. However, gathering NGS data for organisms with very large genomes, such as amphibians, remains challenging because it is still unclear how the current methods perform. Here, we use the Genotyping-by-Sequencing (GBS) approach to generate SNP data for the genotyping of two amphibian species that are of conservation concern, the Sardinian brook salamander (Euproctus platycephalus) and the Italian stream frog (Rana italica). Both E. platycephalus and R. italica have very large genomes (5.53 Gb and >20 Gb, respectively) so genomic data are not available for either of them. We used 95 individual samples and one Illumina lane for each species, with an additional lane for E. platycephalus. After filtering, we obtained 961 and 854 high-coverage SNPs for E. platycephalus and R. italica, respectively. Our results suggest that GBS can serve as a reliable and cost-effective method for genotyping large amphibian genomes, including non-model species.