Evolutionary History of the Galápagos Rail (1 Viewer)

[Fred Ruhe]

Jaime A. Chaves, Pedro J. Martinez-Torres, Emiliano A. Depino, Sebastian Espinoza-Ulloa, Jefferson García-Loor, Annabel C. Beichman and Martin Stervander, 2020

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

Diversity 2020, 12(11), 425
https://doi.org/10.3390/d12110425

Free pdf: https://www.mdpi.com/1424-2818/12/11/425

Abstract: https://www.mdpi.com/1424-2818/12/11/425

The biotas of the Galápagos Islands are one of the best studied island systems and have provided a broad model for insular species’ origins and evolution. Nevertheless, some locally endemic taxa, such as the Galápagos Rail Laterallus spilonota, remain poorly characterized. Owing to its elusive behavior, cryptic plumage, and restricted distribution, the Galápagos Rail is one of the least studied endemic vertebrates of the Galapagos Islands. To date, there is no genetic data for this species, 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 the recent past. Here, we examine the genetics of Galápagos Rails using a combination of mitogenome de novo assembly with multilocus nuclear and mitochondrial sequencing from both modern and historical 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 years ago. A separate analysis of one nuclear and two mitochondrial markers in the larger population samples demonstrates a shallow population structure across the islands, possibly due to elevated island connectivity. Additionally, birds from the island Pinta possessed the lowest levels of genetic diversity, possibly reflecting past population bottlenecks associated with overgrazing of their habitat by invasive goats. The modern and historical data presented here highlight the low genetic diversity in this endemic rail species and provide useful information to guide conservation efforts.

Keywords: ancient DNA; genetic diversity; island colonization; Laterallus spilonota; Rallidae; phylogenetics

Enjoy,

Fred

 

[Fred Ruhe]

Figure 1. Dated phylogenies of the family Rallidae showing the origin of the Galápagos Rail Laterallus spilonota based on (a) all coding sequences of mitochondrial genes (dataset mtCDS; GenBank accession numbers stated at tips); and (b) the mitochondrial genes cytochrome b and cytochrome oxidase I, and the coding sequence of the nuclear recombination-activating gene 1 (dataset 2mt1nc; for GenBank accession numbers and taxon selection, see Data Accessibility). The chronograms are based on a relaxed clock model with fossil-based calibrations of stem Rallidae and crown Gruiformes. We also ran alternative analyses in which the Rallidae calibration was applied to the crown node, yielding small differences in the estimated node ages (see Table 1). Nodes that were time-calibrated are indicated with an asterisk, and the prior densities are drawn in salmon. Posterior probabilities (PP) filled circles (PP = 1.0), open circles (0.950  PP  0.995), or stated at nodes if lower. Node are drawn at median ages, with the 95% highest posterior density represented with blue bars. Shading represent geological periods (Paleogene to Oligocene) and epochs of the Neogene period: Miocene, Pliocene (Pli), and Pleistocene (Ple). Every ten million years is indicated with dashed vertical lines. Illustrations reproduced with permission from Lynx Edicions

Fred

 

[Jim LeNomenclatoriste]

It would be interesting if they studied the phylogeny of genus Laterallus (sensu lato) in its entirety, especially if they included Laterallus levraudi and ruber in order to know their exact position. I think and hope the phylogeny of this genus will be resolved in a short time