Low genetic variability in the endangered Colombian endemic freshwater turtle Podocnemis lewyana (Testudines, Podocnemididae)

Abstract

The Magdalena River Turtle (Podocnemis lewyana) is a Colombian endemic species, endangered due to human exploitation and habitat destruction. To date, this species is poorly known ecologically and data on its genetic diversity are lacking. Here we report on the first genetic survey of the species across its distribution range. We obtained mitochondrial DNA sequences (488 bp) of the cytochrome b gene from 109 individuals. Samples belong to populations located at several different localities, grouped in five regions, along the four main river basins: Magdalena, Cauca, San Jorge, and Sinú drainages. We found two haplotypes, which differ in only one nucleotide substitution and which are represented with different frequencies in the five geographic regions. These results suggest that P. lewyana harbors little genetic variation and is a genetically uniform species, but more variable markers (i.e., microsatellites) should be used to unravel fine-scale phylogeographic structures in this species.

Trade in non-native, CITES-listed, wildlife in Asia, as exemplified by the trade in freshwater turtles and tortoises (Chelonidae) in Thailand

“…Freshwater turtles and tortoises are traded worldwide (e.g. Georges et al, 2006;O'Brien et al, 2003;Vargas-Ramirez et al, 2007) and in Asia to the point where it has been termed a crisis (van Dijk et al, 2000). They are traded for their meat, to be used as ingredients in traditional medicines and, increasingly so as pets (Shepherd, unpubl.…”

Effects of Incubation Temperature on Sex Determination in the Endangered Magdalena River Turtle,Podocnemis lewyana

“…), compared with our southern population (mean ambient temperature 288C, elevation 150 m a.s.l.). However, previous studies have detected low genetic variability and weak population differentiation in this species, which are most likely attributable to genetic drift (Vargas-Ramírez et al 2007, such that other causes should also be considered. For instance, differences between populations may also be attributable to variation in maternal allocation of yolk hormones, as has been reported for P. lewyana (Páez et al 2015) and other turtles (Janzen et al 1998;Bowden et al 2000;Ramsey and Crews 2007), or even trans-generational effects of incubation temperature reported in other reptile species (i.e., inheritance of the parents' thermal sensitivity at which their sex was determined during embryonic development; Warner et al 2013).…”

“…48C (Páez et al 2009). Podocnemis lewyana is endemic to Colombia and is listed as Endangered (Castaño-Mora 2002; International Union for Conservation of Nature [IUCN] 2015), although the continuing population reduction attributable to human predation and habitat degradation may require relisting it as Critically Endangered (Vargas-Ramírez et al 2007;Restrepo et al 2008;Páez et al 2012).…”

Geographic Variation in Sex Determination Patterns in the River TurtlePodocnemis lewyana: Implications for Global Warming

“…Fragmentation impedes short-and long-distance dispersal processes, and smaller habitat patches sustain smaller populations that show lower genetic and phenotypic variability, a prerequisite for rapid adaptive responses (Hof et al, 2011). Indeed, this species has extremely low neutral genetic diversity (Restrepo et al, 2008a;Vargas-Ramírez et al, 2007, 2011 and medium-sized populations (Pá ez et al, 2015b). Nevertheless, neutral genetic diversity is a poor predictor of additive genetic variation for traits that influence fitness (Reed and Frankham, 2001), so further molecular studies with nonneutral markers are needed in this species to better predict the impact in this trait.…”