Environmental and anthropogenic impacts on intra-specific variation in leatherback turtles: opportunities for targeted research and conservation

Intra-specific variation in life history traits and/or population trends provides ‘natural experiments’ to identify causes of observable differences among populations of organisms. Geographically widespread marine species, for example, can experience variation in both environmental and anthropogenic impacts across their ranges that can differentially influence expression of life history traits and population dynamics in separate populations. For example, body size and reproductive output differences among geographically separate, conspecific populations of leatherback turtles Dermochelys coriacea have been linked to variations in environmentally driven resource availability, which differentially affect the resilience of leatherback populations to anthropogenic pressures. Specifically, differences in life history traits and population trends among breeding populations of leatherbacks that forage in the eastern Pacific versus Atlantic Ocean reflect the variable nature of resource availability in the eastern Pacific. These environmentally driven life history differences have contributed to divergent population responses to anthropogenic sources of mortality. In this review, we provide a synoptic view of this body of research and conclude with strategic recommendations for future research and conservation initiatives. This approach has implications for other widely distributed marine species with variations in life history traits that make them more susceptible to humandriven population declines.