Evolution of limb regeneration
Salamanders are the only tetrapods capable of regenerating limbs as adults, however the evolutionary origin of this remarkable ability remains unclear. The only other sarcopterygian capable of regenerating its fin endoskeleton are the lungfishes. Regeneration of dermal fin rays is common among teleost fish, yet fin endoskeleton regeneration has only been reported in living representatives of the non-teleost clade Cladistia, family Polypteridae. Therefore, the explanation for the phylogenetic distribution of vertebrate appendage regeneration as a trait remains elusive. Currently, we are combining experimental studies in lungfish and non-teleost actinopterygians with comparative RNA-seq analyses of regenerating fins and limbs to uncover the evolutionary origin of limb regeneration.
Eye development in the four-eyed fish Anableps anableps
The evolution and development of the eye has intrigued developmental biologists for centuries. Aside from partial or complete loss, few vertebrates display substantial modifications to the eye morphology. The four-eyed fish Anableps anableps consists in a unique model system to study eye Evo-Devo due to its distinctive eye structure. Featuring “split eyes“, this species is capable of looking above and under the water level, using distinct aerial and aquatic pupils and corneas. The retina is divided into dorsal and ventral regions and photoreceptors have been shown differential expression pattern in the adult fish. We have characterized at least seven distinct larval stages for A. anableps and produced eye transcriptomes to identify visual and non-visual opsins. We hope our result of this study will shed light on the molecular basis of this innovative feature.
The colonization of the terrestrial environment by vertebrates and the subsequent adaptive radiation of the Tetrapoda was a transformative evolutionary event. The coelacanths and lungfishes are the only extant non-tetrapod Sarcopterygian taxa, and as they represent the closest living sister lineages to the tetrapods, have the potential to provide deep insights into the molecular changes which accompanied the transition from an aquatic existence to a terrestrial one. We are currently developing in vitro fertilization protocols for obtaining lungfish embryos, with the goals of producing staging tables, SOPs for breeding, husbandry, embryo production, and lab procedures.
Song learning in amazonian birds
The memorization and production of song in songbirds share important parallels with the process of speech acquisition in humans. In songbirds, these processes are dependent on a group of specialized telencephalic nuclei known as the song system: HVC (used as a proper name), RA (robust nucleus of arcopallium), LMAN (lateral magnocellular nucleus of the nidopallium) and striatal Area X. A recent study suggested that the arcopallium of the Sayornis phoebe, a non vocal learner suboscine species, contains a nucleus with some properties similar to those of songbird RA, suggesting that the song system may have been present in the last common ancestor of these groups. We are studying another suboscine, the Amazonian endemic Willisornis poecilinotus. Our preliminary findings suggest that an arcopallial region with some RA-like properties was present in the ancestor of both Suboscines infraorders Tyranni and Furnarii, possibly an ancestral feature of Passeriformes.