Chromosomal Evolution in the Brazilian Geckos of the Genus <i>Gymnodactylus</i> (Squamata, Phyllodactylidae) from the Biomes of Cerrado, Caatinga and Atlantic Rain Forest: Evidence of Robertsonian Fusion Events and Supernumerary Chromosomes

Abstract

Chromosomes of the South American geckos Gymnodactylus amarali and G. geckoides from open and dry areas of the Cerrado and Caatinga biomes in Brazil, respectively, were studied for the first time, after conventional and AgNOR staining, CBG- and RBG-banding, and FISH with telomeric sequences. Comparative analyses between the karyotypes of open areas and the previously studied Atlantic forest species G. darwinii were also performed. The chromosomal polymorphisms detected in populations of G. amarali from the states of Goiás and Tocantins is the result of centric fusions (2n = 38, 39 and 40), suggesting a differentiation from a 2n = 40 ancestral karyotype and the presence of supernumerary chromosomes. The CBG- and RBG-banding patterns of the Bs are described. G. geckoides has 40 chromosomes with gradually decreasing sizes, but it is distinct from the 2n = 40 karyotypes of G. amarali and G. darwinii due to occurrence of pericentric inversions or centromere repositioning. NOR location seems to be a marker for Gymnodactylus, as G. amarali and G. geckoides share a medium-sized subtelocentric NOR-bearing pair, while G. darwinii has NORs at the secondary constriction of the long arm of pair 1. The comparative analyses indicate a non-random nature of the Robertsonian rearrangements in the genus Gymnodactylus.

Out of the deep: Cryptic speciation in a Neotropical gecko (Squamata, Phyllodactylidae) revealed by species delimitation methods

“…We found no evidence for the existence of G. geckoides populations in the Cerrado as previously suggested by Pellegrino et al (2009). These authors found one specimen in 'Barra do Garças' (one of our sampled locations in central Cerrado) to have an identical karyotype to G. geckoides, and suggested it was a potential relict population of G. geckoides.…”

“…Dissimilarities noted between G. amarali and G. geckoides include ecological differences such as clutch and egg sizes (Colli et al, 2003), karyological differences in chromosome number and type (Pellegrino et al, 2009), and morphological differences in pholidosis and coloration patterns (Cassimiro and Rodrigues, 2009;Vanzolini, 1953Vanzolini, , 2005. Nonetheless, it remains unclear whether the widespread Cerrado populations of G. amarali form a monophyletic group in relation to its Caatinga counterpart.…”

“…Nonetheless, it remains unclear whether the widespread Cerrado populations of G. amarali form a monophyletic group in relation to its Caatinga counterpart. In fact, it was proposed that relict populations of G. geckoides might be present in the core of the Cerrado region (Pellegrino et al, 2009), because the karyotype of one specimen was identical to the karyotype observed in G. geckoides populations. In addition, extensive chromosomal polymorphism has been observed within and between G. amarali populations (Pellegrino et al, 2009), as well as great morphological variation among populations (Cassimiro and Rodrigues, 2009;Vanzolini, 1953Vanzolini, , 2005.…”

“…In fact, it was proposed that relict populations of G. geckoides might be present in the core of the Cerrado region (Pellegrino et al, 2009), because the karyotype of one specimen was identical to the karyotype observed in G. geckoides populations. In addition, extensive chromosomal polymorphism has been observed within and between G. amarali populations (Pellegrino et al, 2009), as well as great morphological variation among populations (Cassimiro and Rodrigues, 2009;Vanzolini, 1953Vanzolini, , 2005. As such, it is possible that populations treated under the name G. amarali are paraphyletic in relation to G. geckoides and, moreover, that differences among G. amarali populations reflect the existence of cryptic species.…”

Genomic Distribution of Telomeric DNA Sequences – What Do We Learn from Fish About Telomere Evolution?

“…Similar location of the telomeric repeats in one and three meta-submetacentric chromosomes in the Brazilian lizards, Leposoma guianense and L. oswaldoi, respectively indicated Roberstonian translocations were involved in the evolution of these lizards' karyotypes (Pellegrino et al, 1999). Centric fusion in the Brazilian gecko, Gymnodactylus amarali also left telomeric repeat DNA sequences at the fusion sites of two chromosomes (Pellegrino et al, 2009). …”