Comparative cytogenetics of the primitive frog, <i>Leiopelma archeyi </i>(Anura, Leiopelmatidae)

Abstract

Chromosomally, Leiopelma archeyi is extremely similar to L. hamiltoni, a closely related species. Both have 2n = 18 chromosomes. Contrary to a previous report, the nucleolar organizer region and secondary constriction in L. archeyi are near the telomere of the smallest, telocentric chromosome, as in L. hamiltoni. The arm-length ratios of all chromosomes are virtually identical in the two species, expect for chromosomes 2 and 3, which show evidence of a past translocation. However, L. archeyi has much less heterochromatin than does L. hamiltoni, and, unlike L. hamiltoni, heteromorphic sex chromosomes are not discernable. These frogs demonstrate two stages in the evolution of sex-chromosome differentiation related to the extent of heterochromatin accumulation.

Genetic variation in the genus Leiopelma and relationships to other primitive frogs

“…The increased genetic divergence of L. hamdtoni relative to other species is paralleled by evidence from chromosomes (GREEN 1988b;GREEN and SHARBEL 1988). Although the karyotypes of these species are extremely similar, L. hamiltoni shows an increase level of heterochromatin compared to L. archeyi.…”

Estudo citogenetico de Pseudopaludicola canga, P. mineira e P. saltica e de cinco populações de Pseudopaludicola sp. (Anura, Leiuperidae)

“…Cromossomos heteromórficos são observados tanto no sistema XX/XY, como os encontrados em espécies de Eupsophus , de Gastrotheca (Schmid et al, 1983;) e de Engystomops petersi 1999), como no sistema ZZ/ZW observados, por exemplo, em Pseudis tocantins , Proceratophrys boei (Ananias et al, 2007) e em anuros marsupiais primitivos do gênero Leiopelma em que a diferenciação dos cromossomos sexuais baseia-se principalmente na aquisição de uma região de heterocromatina que originou um braço curto no cromossomo W Green & Sharbel, 1988;Green & Canatella, 1993;.…”