Evolutionary History of the Galápagos Rail Revealed by Ancient Mitogenomes and Modern Samples

MARTINEZ-TORRES, PEDRO J.; GARCÍA-LOOR, JEFFERSON; DEPINO, EMILIANO A.; BEICHMAN, ANNABEL C.; CHAVES, JAIME A.; ESPINOZA-ULLOA, SEBASTIAN; STERVANDER, MARTIN

Diversity

MDPI

Año: 2020 vol. 12

The biotas of the Galápagos Islands are one of the best studied island systems and haveprovided a broad model for insular species? origins and evolution. Nevertheless, some locallyendemic taxa, such as the Galápagos Rail Laterallus spilonota, remain poorly characterized. Owing toits elusive behavior, cryptic plumage, and restricted distribution, the Galápagos Rail is one of theleast studied endemic vertebrates of the Galapagos Islands. To date, there is no genetic data for thisspecies, leaving its origins, relationships to other taxa, and levels of genetic diversity uncharacterized.This lack of information is critical given the adverse fate of island rail species around the world in therecent past. Here, we examine the genetics of Galápagos Rails using a combination of mitogenomede novo assembly with multilocus nuclear and mitochondrial sequencing from both modern andhistorical samples. We show that the Galápagos Rail is part of the ?American black rail clade?,sister to the Black Rail L. jamaicensis, with a colonization of Galápagos dated to 1.2 million yearsago. A separate analysis of one nuclear and two mitochondrial markers in the larger populationsamples demonstrates a shallow population structure across the islands, possibly due to elevatedisland connectivity. Additionally, birds from the island Pinta possessed the lowest levels of geneticdiversity, possibly reflecting past population bottlenecks associated with overgrazing of their habitatby invasive goats. The modern and historical data presented here highlight the low genetic diversityin this endemic rail species and provide useful information to guide conservation efforts.