Most (if not all) animal and plant species live in association with tenth to thousands of microbes. The roles they play for their host range from the acquisition and processing of food to immune defense. Some bacterial symbionts are so functionally important that the host organism cannot survive without them. By maintaining hosts healthy and alive, microbial symbionts are considered to play essential ecosystem functions either directly or indirectly (e.g., the coral microbiome indirectly provisions habitat). They may also prove to be key in the ability of organisms to acclimatize and adapt to ongoing environmental changes.

My colleagues and I are interested in learning about mechanisms of symbiont acquisition in marine invertebrates and fish, the evolution of microbial symbiosis and the role of symbionts in host adaptability. We are conducting comparative analysis of microbiomes and microbial genomes in sister species that have become separated by the formation of the Isthmus of Panama, approximately 3 million years ago. The division of an ancient seaway created a perfect, natural Darwinian evolutionary experiment in the sea, by creating two oceans with strikingly different geophysical characteristics. The Caribbean became warmer, saltier and nutrient poor whereas the environmental conditions in the Bay of Panama in the Tropical Eastern Pacific (TEP) became more variable, highly influenced by upwelling of deep water when the seasonal trade-winds blow. We are using geminate pairs of hosts as replicated evolutionary experiments to test general theories of host-microbe evolution.