Northern genetic richness and southern purity, but just one species in the Chelonoidis chilensis complex

Abstract

Fritz, U., Alcalde, L., Vargas‐Ramírez, M., Goode, E.V., Fabius‐Turoblin, D.U. & Praschag, P. (2012). Northern genetic richness and southern purity, but just one species in the Chelonoidis chilensis complex. —Zoologica Scripta, 41, 220–232. The Chelonoidis chilensis complex, the sister group of the famous Galápagos tortoises, is a widely distributed group of South American land tortoises, ranging from the dry Chaco of Bolivia, Paraguay and northern Argentina to northern Patagonia. Within this complex, up to three distinct species have been recognized. Using sequence data of the mitochondrial cytochrome b gene and length polymorphisms of 10 microsatellite loci, we investigate genetic differentiation among all three nominal species. We find only negligible differentiation, with decreasing genetic diversity from north to south. We conclude that only one species, Chelonoidis chilensis (Gray, 1870), is valid, with C. donosobarrosi (Freiberg, 1973) and C. petersi (Freiberg, 1973) as its junior synonyms. Morphological variation within C. chilensis sensu lato is in accord with the observation that size variation in chelonians follows Bergmann’s rule, with body size increasing with latitude. The observed phylogeographic differentiation inverses the well‐known pattern of southern genetic richness and northern purity from the northern hemisphere, resulting from dispersal from glacial refugia. This implies that in higher latitudes of both hemispheres genetic diversity may decrease with increasing distance from the refugium. For C. chilensis sensu lato, it seems likely that long‐distance dispersal via rafting on the Desaguadero River led to the foundation of the southernmost populations in northern Patagonia during the Holocene.

Goal-oriented evaluation of species distribution models’ accuracy and precision: True Skill Statistic profile and uncertainty maps

“…302 4a). Both models' predictions generally overlaps with published distribution maps for the 303 species (Waller 1986;Ernst 1998;Richard 1999; Administración de Parques Nacionales 304 2012; Fritz et al 2012) and with the ecoregions where the species has been described 305 (Fig. 2a).…”

“…In Argentina, the species is mainly threatened by habitat 174 degradation and poaching (Chebez 2009); thus is categorized as Vulnerable by the IUCN 175 (Tortoise & Freshwater Turtle Specialist Group 2010) and is CITES listed. In the current 176 study the species is defined after Fritz et al (2012), who concluded that Chelonoidis 177 chilensis (Gray, 1870), C. donosobarrosi (Freiberg, 1973) and C. petersi (Freiberg 1973) (Waller 1986;Buskirk 1993;Ergueta & Morales 1996;Cabrera 1998;Ernst 184 1998;Richard 1999;Gonzales et al 2006;Fritz et al 2012). We merged in a GIS vector 185 layer all reported observations using QuantumGIS 1.8 (Quantum GIS Development Team 186 2012).…”

Gene flow among deeply divergent mtDNA lineages of Testudo graeca (Linnaeus, 1758) in Transcaucasia

“…When topotypic individuals of mixed ancestry are included, FST values are for obvious reasons lower and amount only to 0.10-0.15. Also within other tortoise species, similar or even distinctly higher FST values have been reported (Chelonoidis chilensis, based on 10 microsatellite loci: 0.10-0.21, Fritz et al, 2012a; Gopherus agassizii, based on 20 microsatellite loci: 0.01-0.13, Hagerty and Tracy, 2010; G. polyphemus, based on 9 microsatellite loci: 0.06-0.51, Schwartz and Karl, 2005; Testudo marginata, based on 11 microsatellite loci: 0.05-0.16, Perez et al, 2012). Most notably, based on seven microsatellite loci FST values of up to 0.24 were found within one and the same subspecies of T. graeea, the western Mediterranean T. g. graeea (Gracia et al, 2013).…”

“…The three mtDNA clades A, C and E occurring in our study region differ by 4.15% to 4.90% in uncorrected p distances of the cyt b gene. These values exceed uncorrected p distances as observed among some other congeneric tortoise species (3.7% to 12.7%; Fritz et al, 2012a;Kindler et al, 2012), underlining that species delineation in chelonians should not rely on genetic distances alone (Vargas-Ramirez et al, 2010;Praschag et al, 2011;Stuckas and Fritz, 2011;Fritz et al, 2012a, b;Kindleret al, 2012).…”

<strong>A revision of African helmeted terrapins (Testudines: Pelomedusidae: <em>Pelomedusa</em>), with descriptions of six new species</strong>

“…Between-group divergences below diagonal; within-group divergences on the diagonal in boldface; n = number of sequences. Among the congeneric species reviewed by Vargas-Ramírez et al (2010) and Fritz et al (2012a), the divergences of the mtDNA lineages of Pelomedusa belong to the highest ones observed, and this is also true when the recently reported values for kinosternid turtles (Iverson et al 2013) are considered. When the divergences among the lineages of Pelomedusa are compared with Pelusios species, which represent the genus most closely related to Pelomedusa, it is obvious that the Pelomedusa lineages are highly differentiated and their divergences often exceed those among distinct Pelusios species (Tables 1-4).…”