The Evolutionary Ecology of Animals Inhabiting Hydrogen Sulfide–Rich Environments

Abstract

Hydrogen sulfide (H 2 S) is a respiratory toxicant that creates extreme environments tolerated by few organisms. H 2 S is also produced endogenously by metazoans and plays a role in cell signaling. The mechanisms of H 2 S toxicity and its physiological functions serve as a basis to discuss the multifarious strategies that allow animals to survive in H 2 S-rich environments. Despite their toxicity, H 2 S-rich environments also provide ecological opportunities, and complex selective regimes of covarying abiotic and biotic factors drive trait evolution in organisms inhabiting H 2 S-rich environments. Furthermore, adaptation to H 2 S-rich environments can drive speciation, giving rise to biodiversity hot spots with high levels of endemism in deep-sea hydrothermal vents, cold seeps, and freshwater sulfide springs. The diversity of H 2 S-rich environments and their inhabitants provides ideal systems for comparative studies of the effects of a clear-cut source of selection across vast geographic and phylogenetic scales, ultimately informing our understanding of how environmental stressors affect ecological and evolutionary processes.