SCRIPPS INSTITUTION OF OCEANOGRAPHY FACULTY CANDIDATE SEMINAR
DATE: April 12th, Wednesday, 12:15pm
LOCATION: Hubbs Hall 4500
TITLE: The role of environmental gradients in coral diversity: From deep time to the deep sea
The ecological and evolutionary processes that interact to shape community structure are poorly studied in the largest environment on Earth – the deep sea. Yet, the deep sea is critical to the planet’s climate regulation and harbors a vast amount of undiscovered biodiversity, much of which is threatened by anthropogenic impacts including changing ocean conditions. To address how changing environmental conditions impact coral diversity in the deep sea, I coupled population genetic data, phylogenetic data, and morphological traits with environmental data. I found that depth (and the co-factors that vary with it) exhibited a greater effect on genetic differentiation than horizontal distance in deepwater coral populations. These results provide support for the depth-differentiation hypothesis and strengthen the notion that adaptive divergence along a depth gradient is an important mechanism in structuring deep-sea populations. In related work, I also found that octocoral communities sort along an environmental gradient of depth. Closely related octocoral species sorted into discrete depth strata on the upper slope of the Gulf of Mexico (250-800 m) likely due to barriers imposed by water masses followed by adaptive divergence. At depths > 2000 m, octocorals were more closely related than expected by chance due to the diversification of chrysogorgiids and isidids, which retain conserved traits that perhaps impart survival at deeper and/or colder depths. Trait lability across depth was also observed for several characters, demonstrating that environmental gradients can influence octocoral morphology. Finally, to inform predictions of future ocean change, it is useful to resolve when particular clades of corals and their traits arose in time and to identify any possible connections between those evolutionary events and paleoclimate conditions. To address this, I am creating a robust, time-calibrated phylogeny of the class Anthozoa using a targeted-genomic approach. To date, I have sequenced 1,778 loci from 33 anthozoan species. Sequencing of 160 additional anthozoans is currently underway to resolve key regions in the phylogeny, further understand character evolution in the class, and identify any links between past climate conditions and evolutionary events.