Emerging Approaches in Amphibians: Evolution, Development, and Beyond

Amphibians (anurans, urodeles, and caecilians) have prominent features, such as biphasic life history, metamorphosis, phenotypic plasticity, and regeneration. They show large species diversity reflecting their long evolutionary history and flexible phenotypic changes depending on surrounding environments. Because of the experimentally useful traits such as larger eggs and external fertilization, anuran amphibians have been used as important model animals in biology, especially for early embryonic development and cell biology. Urodeles have robust regeneration ability, which is attractive to evolutionary biologists. Although their large genome and relatively long generation time has hampered progress of genetic and evolutionary studies of their intrinsic phenotypes, recent sequencing technologies and genome editing techniques can overcome these difficulties. Amphibian studies with such emerging approaches have been increasingly impactful for genetic and evolutionary studies and can answer fundamental questions in biology (i.e., genome duplication, genetic basis of regeneration ability, etc).

The main goal of our Research Topic is further understanding of amphibian genetics, including both model and non-model species. Considering non-model amphibian species, we can approach genetic backgrounds of species-specific adaptive phenotypes using genome and transcriptome sequencing. We can also infer the population histories (e.g., admixture and speciation) of any local species using genome-wide neutral genetic markers. In addition to Xenopus frogs, new model amphibian species, such as the Iberian ribbed newt (Pleurodeles waltl) and axolotl (Ambystoma mexicanum), have recently been developed. These model species have made it possible to uncover molecular genetic mechanisms behind regeneration and metamorphosis in amphibians using functional genetic approaches. Since functional approaches via genome editing or other methods are sometimes possible for non-model amphibians, such trials and developments of new applications are important. This research improves our understanding of amphibian biology and could have potential impacts for understanding vertebrate genetics.

This Research Topic welcome high-quality Original Research articles and Reviews focused on the following subtopics, though any topics related to amphibian genetics are welcome:
• Inferring population genetics of amphibians using neutral nuclear markers generated by high-throughput sequencing (RAD-seq, MIG-seq, UCE, etc.)
• Comparative genomics to highlight the genetic basis of amphibian-specific phenotypes or signature of selection in their genomes
• New amphibian genome sequencing and subsequent analysis
• Identification of candidate genes and genetic basis of amphibian-specific phenotypes using transcriptome and functional genetics
• Dissecting molecular mechanism of metamorphosis and regeneration in amphibians
• Development and application of functional genomic approaches using non-model amphibians