Hawksbill Genetics Explained
A female hawksbill can mate with several males within one reproductive season; males might also have multiple mates within the same season. © R.P. van Dam
By Alberto Abreu and Robin LeRoux
Molecular genetics offers a valuable set of tools for unraveling the mysteries and histories of many species. These tools have developed rapidly during the past decade, allowing scientists to gain insight into previously intractable questions. In the case of the hawksbill turtle, molecular genetics has described evolutionary patterns, stock identities, geographic distributions, and the presence of hybrids. Genetic techniques have drastically improved our understanding of hawksbill biology and, in turn, have enhanced our ability to manage the species.
Recent Discoveries about Hawksbills from Genetic Studies
Hawksbill lineages in the Indo-Pacific and Atlantic oceans are evolutionarily distinct, a notion that was established previously on a morphological basis but later discarded.
Hawksbills, with their unique diet of sponge, belong to a carnivorous sea turtle lineage that aligns them with the loggerhead and ridley subfamilies.
Hybridization between hawksbills and olive ridleys, loggerheads, or green turtles is sporadically observed, especially in areas where hawksbill populations have declined greatly. In Bahía, Brazil, however, hawksbill-loggerhead hybrids apparently have integrated into the normal population, constituting about 40 percent of the rookery.
Nesting hawksbill populations are not closed, as previously thought. Rather, they share developmental and foraging grounds with individuals from multiple genetic stocks, and they migrate internationally, returning to their natal beaches to reproduce. These characteristics highlight the need for regional and multinational management schemes that take into account both nesting and foraging grounds.
Distinctions exist among multiple nesting stocks within geographic regions. For example, there are at least 15 different nesting populations in the Caribbean region.
Clearly, genetic studies have uncovered numerous crucial clues about hawksbill populations worldwide. However, more information—particularly stock identifications for nesting populations in certain regions (for instance, the Eastern Atlantic and Indian oceans)—is necessary to solve many remaining hawksbill mysteries and to develop sound policies to conserve this species globally.
This article originally appeared in SWOT Report, vol. 3 (2008). Click here to download the entire article as a PDF.