Meeting Abstract
64.8 Wednesday, Jan. 6 Using behavioral processes to predict geographic distributions: Implications of hatchling sea turtle migration on spatial patterns of nest abundance PUTMAN, N.F.*; SHAY, T.J.; BANE, J.M.; LOHMANN, K.J.; UNC Chapel Hill; UNC Chapel Hill; UNC Chapel Hill; UNC Chapel Hill nputman@email.unc.edu
Variation in individual abundance across a species’ reproductive range is often correlated with factors that increase offspring fitness at a given location. However, for highly mobile species it may be important to specifically consider how the movement of migratory offspring might also influence which areas within a region are used for reproduction. To investigate, two nesting assemblages of sea turtles were considered: loggerhead turtles (Caretta caretta) along the southeastern U.S. and Kemp’s ridley turtles (Lepidochelys kempii) along the western Gulf of Mexico. Using loggerhead nesting data that spanned two decades, a simple regression model considering only distance hatchlings must migrate from the beach to the Gulf Stream System (which assists their migration across the Atlantic) can account for nearly all of the spatial variation in loggerhead nest density at regional scales and almost half at the smaller scale of Florida counties. For the Kemp’s ridley, standardized nesting records are not available across their reproductive range; additionally there is no stable ocean current to which they migrate. Thus, for this analysis, hatchling dispersal was simulated across the Kemp’s ridley nesting range and recruitment to nursery habitat was tracked. Dispersal from the region where most nesting presently occurs allowed for more recruitment to juvenile foraging grounds than did dispersal from surrounding regions. These studies provide insight into what may be a fundamental ecological principle: natural selection shapes the geographic distribution of migratory animals by favoring reproduction in areas that facilitate migration while simultaneously selecting against the use of areas from which successful migration is difficult.
