Climate change poses further threats, though signs of population increases have been seen more recently in the wake of conservation initiatives. The ensuing period coincided with falling populations of many turtles, through activities including egg and meat exploitation, coastal urbanisation and pollution. Taking into account that the two species mature between the ages of 20 and 40, while two hybrid generations have been observed so far, her team thinks high-frequency cross-breeding started before 1980. She says that interbreeding is aided in Bahia by the overlapping nesting seasons of hawksbills and loggerheads. вЂIf you think about primates, it would be something like humans and lemurs hybridising,вЂ™ said Dr VilaГ§a.Дr VilaГ§a is investigating the causes of this hybridisation and its implications in the TurtleHyb project. Some cases of turtle hybridisation involve crosses between species that diverged more than 60 million years ago, which is very unusual. вЂThereвЂ™s evolutionarily an interesting question there: what happens when these genomes meet again?вЂ™ вЂYou donвЂ™t see that a lot in the animal kingdom вЂ“ species that have diverged so long ago and theyвЂ™re capable of still hybridising,вЂ™ said Dr Sibelle Torres VilaГ§a, a population geneticist at the University of Ferrara in Italy. It could also shed an intriguing light on the potential role played by hybridisation in long-term evolution, given that hawksbills and loggerheads are estimated to have diverged genetically as long as 30 million years ago. Understanding why this is happening may be important for informing conservation efforts because hybridisation can have consequences for speciesвЂ™ survival. These hybrids can then produce viable second-generation offspring by interbreeding, or вЂbackcrossingвЂ™, with members of either parent species.

However, in BrazilвЂ™s northeastern state of Bahia, genetic analysis has uncovered that as many as 30 to 40% of female hawksbills at some nesting sites are, in fact, first-generation hybrids resulting from cross-breeding with loggerheads. Hybridisation has been observed in five of the worldвЂ™s existing species, yet much of this has been at low levels. While efforts are ongoing to protect turtles, part of the puzzle that requires more knowledge concerns the effects of interspecies mating, or hybridisation вЂ“ particularly between hawksbills ( Eretmochelys imbricata) and loggerheads ( Caretta caretta) in one area of Brazil.

Seaturtle gene sequence s