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Differences in environmental conditions such as those between lakes and streams can produce phenotypic variation and ultimately promote evolutionary diversification. Some species of newts and salamanders can occupy these habitats and express alternative phenotypes: metamorphs that lose gills at metamorphosis and paedomorphs that retain them at the adult stage. Whereas this process is facultative in some species, it is obligatory in others, thus suggesting that isolation and environmental pressures may have canalized developmental pathways. In this study, we focused our research on the Pyrenean brook newt, Calotriton asper, which is present in both lakes and streams, but whose fully aquatic paedomorphic individuals are only present in lakes. We aimed to determine the genetic structure and differentiation of two paedomorphic populations, including their surrounding stream and lake metamorphic populations, to test whether populations of paedomorphs can constitute evolutionary significant units. Although gene flow was identified between lakes and nearby stream populations, there was a low percentage of dispersers, and the paedomorphic populations were genetically differentiated from the populations of metamorphs. It is likely that the studied lakes have offered peculiar conditions that have allowed the development of a paedomorphic phenotype. These populations and phenotypes therefore constitute good models to understand local adaptations. As each of these populations of paedomorphs can be considered evolutionary significant units that cannot be replaced by other nearby populations in case of a population crash, conservation actions should be focused directly on them. The rare lake populations of the Pyrenean brook newt Calotriton asper with individuals exhibiting paedomorphosis (retention of larval traits at the adult stage) constitute evolutionary significant units. Because of their genetic differentiation with surrounding stream and lake populations, they can be considered at a high risk of extinction due to the introduction of invasive species such as fish and chytrids that have already been found in some of them. Conservation measures should therefore target in priority these peculiar populations. Photograph: M. Denoël. [ABSTRACT FROM AUTHOR]

The article discusses a study on mantellid frogs found in Madagascar. As per the study, the pattern of eye color of the frogs is significantly correlated with its ecology and habitats. In the study, it was found that significant number tree frogs of the genus Boophis have a bright colored iris, often with annular elements and a blue-colored iris periphery (sclera) diurnal, terrestrial and aposematic Mantella frogs have a uniformly black iris, and terrestrial leaf-litter dwellers have an iris horizontally divided into an upper light and lower dark part. The study presents a correlation between the presence of a frenal streak and a dark tympanic patch in the frogs. Further as per the study frenal streak and tympanic patch were associated with the horizontally divided iris color.

Traditional methods of phylogenetic reconstruction and species delimitation may be impeded by frequent hybridization among lineages. In this study, we conducted phylogenetic and clustering analyses of ddRAD genomic data on the entire genus Salamandra, which includes six species and over 25 subspecies of terrestrial salamanders. We expanded previous datasets to include missing subspecies and incorporated new samples, with an emphasis on secondary contact zones. Results obtained from a full dataset of 392 individuals (356,874 bp; 24,192 SNPs) were compared with those obtained after excluding substantially admixed individuals (n = 95; 835,467 bp; 51,557 SNPs) to explore the consequences of introgression on phylogenetic inference and taxonomic arrangement of subspecies. We found conflicting phylogenetic placements for taxa represented by many admixed individuals (identified by clustering ancestries). In contrast, a time-calibrated tree constructed without hybrids largely agrees with previous phylogenetic hypotheses. Within S. atra, we found paraphyly of S. atra atra, suggesting an additional candidate subspecies. Within S. infraimmaculata, two lineages are assignable to known subspecies and we additionally identified a third, deeply diverged lineage sampled near the Turkish/Syrian border. In S. algira, we found limited admixture between the subspecies S. a. tingitana and S. a. splendens despite their geographic proximity. Finally, within S. salamandra, we detected significant levels of hybridization between subspecies, which blurred their phylogenetic relationships, although the removal of admixed samples in subset analyses clarified the situation in most cases. Monophyly was recovered for subspecies that were previously found paraphyletic, including S. s. salamandra, S. s. gallaica, and S. s. fastuosa. Salamandra s. "alfredschmidti" was confirmed to be a junior synonym of S. s. bernardezi. Previously disputed subspecies, like S. s. "molleri" and S. s. "hispanica", correspond to separated lineages but are affected by admixture with other lineages. Further newly identified candidate subspecies in S. salamandra included a southern lineage within S. s. wer-neri and a western lineage within S. s. bernardezi. Finally, we re-evaluate the status of recognized subspecies in Salamandra, based on evidence from multiple delimitation criteria. Given that the evolutionary history could not be resolved for all subspecies, we highlight taxa within Salamandra that warrant further molecular examination and taxonomic revision, notably within the S. s. gallaica/"molleri"/bejarae complex. This study illustrates the impact of hybridization in phylogenetic analyses and its downstream effects in the identification of conservation units and their naming in the Linnean classification. [ABSTRACT FROM AUTHOR]