Abstract
Global environmental change is rapidly driving deterioration of many
ecosystems- such as coral reefs- though the rate of decline could be
offset by genetic adaptation. We aimed to identify which environmental
gradients drive local adaptation in two common corals across the Florida
Keys Reef Tract, Porites astreoides and Agaricia agaricites. Both
species contained three genetically distinct lineages distributed across
depths in a remarkably similar way. Additionally, each lineage harbored
genetic variation that aligned with other environmental gradients. The
most commonly highlighted driver of within-lineage genetic structure was
temperature during the coldest winter month, which is warmer at offshore
sites especially in the upper Keys. Other repeatedly highlighted
environmental drivers were high variation in bottom temperature at
nearshore sites along the main island chain, more pronounced ocean
stratification west of Key West, and outlying values of several water
quality parameters (such as dissolved oxygen, carbon, turbidity, and
salinity) at nearshore and Florida Bay locations of the lower and middle
Keys. Synthesizing these results, we provide a map of adaptive
neighborhoods in the Florida Keys that are likely to harbor
differentially adapted coral populations, which can be regarded as
different genetic stocks from the perspective of reef conservation and
restoration.