Karyotypic Evolution in Gehyra (Gekkonidae: Reptilia) I. The Gehyra Variegata-Punctata Complex.

Abstract

A karyotypic analysis of populations of the gekkos Gehyra variegata and G. punctata reveals three chromosome races in G. variegata (2n = 44; 2n = 40a; 2n = 40b), and three in G. punctata (2n = 44; 2n = 42; 2n = 38). The chromosome races have differentiated by a series of chromosome fusions. The ordered nature of these changes suggests that the phylogenetic relationships of the races cut across the current taxonomy, and it is argued that there is but one 2n = 44 race, occurring as a number of morphologically distinct populations, two of which were erroneously described as the separate Gehyra species. Isolated populations within a number of the chromosome races show pronounced morphological differences. It is believed that these gekkos are an ancient Australian group which differentiated chromosomally during a number of colonizing radiations. Since then, populations within each race have been isolated by geographic barriers and have speciated allopatrically. This suggests that the chromosome races are at least good species and may be of a higher taxon.

Evaluating evolutionary history in the face of high gene tree discordance in Australian Gehyra (Reptilia: Gekkonidae)

“…The content of our two groups mostly matches the subdivision proposed by Mitchell (1965) and King; however, two of King's australis group species, G. occidentalis and G. xenopus, fall into our variegata clade. Species contained within the initial concepts of the G. australis clade (Figure 2) were, on average, larger-bodied taxa (King, 1983;Horner, 2005) associated with the tropical, subtropical and monsoonal tropics of Australia and southern New Guinea, whereas the variegata clade comprised smaller bodied species associated with the arid and semi-arid zones (King, 1979;Moritz, 1986). Both G. occidentalis and G. xenopus are relatively large bodied (maximum SVL (Snout-vent length) 465 mm), both are confined to the monsoonal Kimberley region of Western Australia and both branch near the base of the G. variegata clade.…”

“…The Australian Gehyra radiation has proven to be taxonomically troublesome in the past, as considerable genetic, karyotypic and allozyme variation does not manifest in easily recognizable morphological variation. Thus, many species comprise multiple morphological isolates, distinct chromosome races, allozymeoperational taxonomic units and mitochondrial clades (King, 1979(King, , 1982(King, , 1983(King, , 1984Moritz, 1984Moritz, , 1986Moritz, , 1992Sistrom et al, 2009;Sites and Moritz, 1987). As a relatively recent radiation (King, 1984), gene tree discordance in Gehyra is expected owing to ILS (Edwards, 2009).…”

“…King (1979King ( , 1983King ( , 1984 summarized many of these assumptions, including (1) A recent Asian origin for Gehyra (King, 1984); (2) Australian Gehyra form two major species complexes (Mitchell, 1965)-the G. variegata complex characterized by small bodied species associated with arid regions (King, 1979) and the Gehyra australis species complex characterized by larger bodied animals associated with tropical, subtropical and monsoonal regions (King, 1983); and (3) that radiation within these two complexes was due to allopatric divergence and chromosomal rearrangement with sequential radiations of allopatrically derived species from 2n ¼ 44 chromosome ancestor(s), to 2n ¼ 42 chromosome species and to 2n ¼ 40 and 2n ¼ 38 chromosome species simultaneously. However, King's proposal was criticized as premature given the incomplete taxonomy of the genus and lack of data demonstrating reproductive isolation of allopatric chromosome races (Moritz, 1992;Sites and Moritz, 1987).…”

“…The focal organismal group for our study-Gehyra-is a large genus of geckos from the family Gekkonidae (Han et al, 2004;Russell and Bauer, 2002), comprising 36 species occupying a wide range of habitats from Indochina throughout most of Oceania and Melanesia (King, 1979;Russell and Bauer, 2002). The Australian Gehyra radiation represents the bulk of the group's diversity comprising 19 largely endemic species (Horner, 2005;Sistrom et al, 2009).…”

Spots before the eyes: revision of the saxicoline geckos of the Gehyra punctata (Squamata: Gekkonidae) species complex in the Pilbara region of Western Australia

“…no mention was made of G. dubia [Macleay, 1877], indicating Bustard was unaware of this name). In the late 1970s and early 1980s, work on documenting the karyotypes of widely distributed Gehyra taxa in Australia by King and Moritz began to reveal the true confusion in the genus and resulted in many species descriptions (reviewed in King 1979Moritz 1986;Sistrom et al 2009Sistrom et al , 2013. Based on widely varying karyotypes across the region, new species were erected to accommodate several chromosomally and morphologically divergent populations, i.e.…”