Collaborative Research: Gluers, Grippers, and Gougers: Host-adapted Diversification of Barnacles Epizootic with Marine Megafauna and their Turtlescape Genomics

College Of Charleston, Charleston SC

Investigators

Abstract

Sea turtles and whales serve as the only attachment surfaces for approximately two dozen species of barnacles. These stationary crustaceans have evolved to seek out specific hosts as mobile homes because they provide barnacles an easy means of dispersing and feeding, while giving them protection from predators. Barnacles attach to turtles and whales by three mechanisms: there are “gluers” which cement themselves to shell and other firm body parts with minimal to no invasive action; “grippers” which cling to soft epidermis by means of skin-pinching mechanics; and “gougers” which can penetrate tissue, scutes, scales, and sometimes to the underlying bone. This research will map genetic tags from barnacles collected worldwide to 1) study host choice and the evolutionary history of barnacle attachment, 2) describe to what extent barnacles may be a “fingerprint” management tool for tracking sea turtle movements, and 3) establish a baseline distribution of barnacle genetic types for monitoring alterations in species ranges due to climate change. This research will train undergraduate and graduate students in genetics and evolutionary analyses as well as field methods in marine biology via a field course in Costa Rica. Outreach includes the development of museum exhibits and the publication of popular articles for a broad audience. The evolutionary history and species delineations of the coronuloid barnacles (Arthropoda: Crustacea: Cirripedia) is uncertain. Specifically, little is known of their route to epizoism, their degree of dependence on hosts for dispersal and diversification, their pathways to variable attachment mechanisms, and their contemporary phylogeographic distributions. The researchers aim to address these deficiencies through phylogenetic and population genomic analysis with three principle objectives: 1) construct a definitive phylogeny for the whale and turtle barnacles and map to it the evolutionary chronology of their gluing, gripping, and gouging attachment modes; 2) compare global phylogeographic patterns using genome-wide markers for the three most-common barnacle species from the four most-common sea turtle species, assessing population connectivity in the context of oceanographic larval dispersal (geographic localities) vs. host transport (host lineages); and 3) test whether barnacle genetic lineages within species assort with respect to sea turtle species. A network of international collaborators at 16 global localities will help collect, from more than 130 sea turtles, ~2,200 total barnacle specimens for population genomic analysis. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.