VERY LOCAL ADAPTATION IN CORAL THERMAL TOLERANCE LIMITS: EVIDENCE FROM 2.5 COUNTRIES, 2 OCEANS, AND 2 SPECIES
It is well known that the same species of coral from different latitudes can differ in bleaching thresholds by as much as a few degrees. This has historically been attributed to an evolutionary tuning of coral thermal limits to the conditions of their local environment (i.e. local adaptation). Recently, a growing body of evidence is finding that corals from different micro-habitats within the same reef-system separated by only 500m to 5km can differ in bleaching tolerance by as much as or more than corals from contrasting latitudes 100s - 1000s of kilometers apart. Here, we present data comparing the response of corals from three study sites to experimental heat stress: a set of shallow back-reef pools in American Samoa, a nearshore and offshore patch reef in the Florida Keys, and a back reef and fore reef in Belize. In all three cases, corals from the micro-habitats with the highest amount of daily variability in temperature showed the greatest resistance to bleaching compared to conspecifics from sites with more stable temperatures. These differences were consistent despite long periods of common garden acclimation (30, 36, and 240 days for Belizean, Samoan, and Floridian corals respectively), and similar symbiont types. As a whole, these results combined with those of other recent studies suggest that the amount of thermal variability may play an important role in shaping coral bleaching thresholds and that local adaptation may be as common at within-reef scales as it is thought to be across latitudinal gradients in ocean temperatures.
Barshis, D. J., Old Dominion University, USA, firstname.lastname@example.org
Maxie, B. K., Old Dominion University, USA, email@example.com
Rosen, P., Nyack High School, USA, firstname.lastname@example.org
Jones, D. D., Old Dominion University, USA, email@example.com
Location: 313 B
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