Species delimitation and biogeography of the Ryukyu ground geckos,Goniurosaurus kuroiwaessp. (Squamata: Eublepharidae), by use of mitochondrial and nuclear DNA analyses

Abstract

In the Ryukyu Archipelago, Japan, Goniurosaurus geckos are currently divided into six allopatric taxa among nearby islands. Recent studies suggested the occurrence of large genetic divergence within a single island and the possible non‐monophyly of a few taxa, but their species delimitation is not well resolved. We investigated the taxonomic relationships between the possibly geographically overlapped, highly diverged entities as well as other island populations via dense sampling. Our mitochondrial and nuclear DNA analyses showed that the two genetic groups were distributed in parapatry within Okinawajima Island and that they were hybridizing in narrow area around the contact zone. Geohistorical evidence suggests that the restricted gene flow has been caused by some intrinsic isolation mechanisms. Thus, we conclude that the two lineages represent full species. Mitochondrial analysis also showed that the genetic differences among other island populations were comparable to those between these species, thereby suggesting the presence of seven full species, including one unnamed taxon. We also discuss the possible cause of this divergence and why it has occurred at such a fine geographic scale.

Origin and intraspecific diversification of the scincid lizard Ateuchosaurus pellopleurus with implications for historical island biogeography of the Central Ryukyus of Japan

“…The partial concordance with discordant boundaries was likely formed by initial allopatric isolations followed by repeated secondary dispersals. During the repeated dispersals, the local genetic elements may have been swept out in some cases but occasionally retained in other cases, as discussed by Kurita et al (2018). Although the vicariance events that isolated the Iheyajima and Kumejima assemblages are unclear, those deserve further consideration given the concordant divergence dates among taxa.…”

“…3). Divergences around 2.5 MYA between the Iheyajima-Izenajima and Okinawajima populations were known for Microhyla okinavensis (around 2.1 MYA; Tominaga et al 2019) and Goniurosaurus kuroiwae (Namiye, 1912) sensu lato (1.7-3.5 MYA; Kurita et al 2018), although the latter species is absent from Izenajima.…”

“…the northern and southern populations did not share any haplotypes except for the widespread haplotype RHWc, whereas the haplotype RHWe was shared by two local samples in northern Okinawajima. Genetic differentiation within Okinawajima was known for two other taxa, Plestiodon marginatus (Kurita & Hikida 2014b) and Goniurosaurus kuroiwae (Kurita et al 2018). Of these, G. kuroiwae exhibited distinct differentiation, with a reproductive barrier between the northern and southern populations.…”

Phylogeny and evolution of habitat preference in Goniurosaurus (Squamata: Eublepharidae) and their correlation with karst and granite-stream-adapted ecomorphologies in species groups from Vietnam

“…Eublepharid geckos of the genus Goniurosaurus Barbour, 1908 comprise 23 saxicolous specialists (Uetz et al 2021) that extend from the Ryukyu Archipelago in Japan, southward through East Asia to northern Vietnam. Goniurosaurus is a well-defined monophyletic group (Grismer 1988) comprised of four monophyletic species groups: the kuroiwae group containing six species endemic to the Ryukyu Archipelago, Japan; the lichtenfelderi group with five species from insular and mainland China and northern Vietnam; the luii group with eight species from northern Vietnam, some of its offshore islands, and southern China; and the yingdeensis group consisting of four species from southern China (Kurita et al 2008;Nguyen et al 2009;Nguyen 2011;Wang et al 2013;Honda and Ota 2017;Liang et al 2018;Qi et al 2020aQi et al , 2020bZhu et al 2020aZhu et al , 2020b. Apart from these species, Goniurosaurus sinensis Zhou, Peng, Huo and Yuan, 2019 is likely a junior synonym of another species from Hainan Island, China and not included herein (Qi et al in progress).…”

Structure and movement of the hybrid zone between two divergent lineages of the Japanese newtCynops pyrrhogaster(Amphibia: Urodela) in central Japan

“…Knowledge of genetic relationships, levels of gene flow, introgression, and structure and maintenance mechanisms of hybrid zones of divergent lineages of organisms in their secondary contact zone will aid our understanding of the allopatric speciation process. Thus, many studies of parapatric lineages have been conducted to reveal the level of gene flow required to delimitate a species (e.g., Fontanella et al, 2017; Kurita et al, 2018).…”