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What is the estimated overall prevalence of these hybrids?

I like the idea of this study a lot, that sea turtles have distinct ecologies, and that a hybrid might be disperse to a place that doesn't match it's features. Sea turtles are somewhat unique in this respect by comparison to other hybrid species. But what is the estimate overall rate of hybridization with respect to each parent population? And what is the expected rate moving forward, into the future? Is hybridization expected to increase? Thanks!

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The overall prevalence of the hybridization phenomenon in Brazilian sea turtles is quite challenging to determine. Nesting numbers fluctuate seasonally, and sampling/DNA analyses are difficult to perform on all females over a reproductive season. Additionally, maternally-inherited mitochondrial DNA can underestimate the occurrence of hybrids in cases where morphology matches mtDNA, and nuclear markers should also be investigated to understand the extent of this process. Studies with mtDNA have reported that approximately 42% of analyzed nesting hawksbills are hybridized with loggerheads, and 36% of nesting loggerheads have also been shown to present mtDNA characteristic of olive ridleys, but these prevalences could be underestimated. The causes behind these hybridization scenarios have not been established, and therefore future rates cannot yet be projected. Nonetheless, possible explanations include uneven population sizes and overlapping reproductive areas and periods, combined with decreased population numbers. Currently, several research teams are working towards a better understanding of the phenomenon, through field observations, analyses of nuclear DNA markers, and partial genome screening of pure parental species, adult hybrids, and their hybrid offspring. We hope that this will elucidate the extent of hybridization in sea turtles in Brazil, and how it affects the behavior and ecology of these animals.

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