Molecular adaptations in the Chinese alligator

In the September 2013 issue of Cell Research Wan et al. report the genome sequence of a single Chinese alligator. They identify several positively-selected molecular adaptations in protein-coding genes that are associated with traits for predation in aquatic habitats. Alligators are top predators, and they are able to ambush prey from underwater, remain submerged for long periods, and can sense small prey. The authors focused on genes that regulated these functions and found unique molecular signatures, including a diving adaptation that allows alligators to tolerate hypoxia and regulate metabolic demands for long periods of submersion. They found gene expansion in olfactory, synaptic, auditory, and immune function genes, as well. This study provides a new perspective into hypoxia resistance by elucidating the genetic signature of aerobic diving, which is a form of voluntarily tolerant hypoxia.