Genetic and molecular adaptations
Dolphins and other marine mammals possess unique adaptations that allow them to thrive in aquatic environments. While many physiological and anatomical adaptations play a clear role in marine mammal phenotypes, less is known about how genetic and molecular adaptations contribute to these phenotypes. In this chapter, we will explore the current understanding of genetic and molecular adaptations of marine mammals, focusing on adaptations that afford dolphins and other marine mammals an elevated tolerance for hypoxia and ischemia during diving. We will summarize the current knowledge of gene gain/loss events, mutations, and alterations in gene regulatory networks that have occurred in marine mammals, as well as unique patterns of gene expression in this group. These changes will be connected to potential resulting physiological adaptations and will also be compared with other species of physiological relevance, such as those living in chronic hypoxic environments. Based on a review of the available literature, we will speculate how molecular adaptations may have shaped physiological structures and systems to allow marine mammals to thrive in aquatic environments.
