Oceanic islands such as Galápagos are privileged settings for studying how species originate and diverge. In this context, the endemic geckos of the genus Phyllodactylus play an important ecological role and, at the same time, remain poorly known from a genetic perspective. They also face threats associated with habitat loss and the presence of introduced species. In response to this reality, this study aimed to analyze the genetic diversity and population structure of six endemic gecko species found on four inhabited islands of the archipelago, as well as to delimit their species boundaries in order to generate concrete inputs for their conservation.
Field sampling was conducted between May and August 2023 on the islands of Santa Cruz, Isabela, Floreana, San Cristóbal, and Fernandina, covering 27 localities in both urban and natural environments. Researchers manually captured adult individuals of the different Phyllodactylus species and obtained small tail tissue samples for genetic analyses, following permits and ethical protocols established by environmental authorities. Using this material, they applied a genomic technique known as RAD-Seq, which allows the analysis of thousands of DNA fragments simultaneously and provides a high-resolution overview of genetic diversity, evolutionary relationships, and patterns of gene flow among populations and species.
The results revealed five well-defined genetic groups corresponding to P. darwini, P. leei, P. baurii, P. galapagensis, and a combined group of P. simpsoni and P. andysabini, leading to the proposal of synonymizing P. andysabini under P. simpsoni due to their minimal genetic differentiation. High differentiation was detected among species, but overall low genetic diversity, especially in P. darwini and P. baurii, which may increase their vulnerability to environmental change. Population structure was associated mainly with geographic barriers and restrictions in gene flow, rather than with human presence, as no strong signals of admixture were observed among populations on inhabited islands. This study highlights the value of genomic tools for understanding the evolutionary history of Galápagos geckos, refining their species delimitation, and defining management units that support their conservation in an archipelago subject to increasing anthropogenic pressures.
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https://doi.org/10.1038/s41598-025-24790-2
