Genetic structure, diversity and distribution of a threatened lizard affected by widespread habitat fragmentation

Determining the generation length and level of morphological and genetic differentiation in the Data Deficient glossy grass skink (Pseudemoia rawlinsoni)

“…Interestingly, the location of the seven genetic lineages within the glossy grass skink were largely concordant with the recognised biogeographic boundaries in southeastern Australia (Chapple et al 2005(Chapple et al , 2011a(Chapple et al , 2011bBryant and Krosch 2016;Dissanayake et al 2022). Assuming 2% sequence divergence per million years, as used in other Australian skinks (Chapple et al 2005;Haines et al 2014), this would indicate a divergence time of between 0.5 million years ago and 2.6 million years, ago during the Pliocene-Pleistocene boundary (Chapple et al 2005;Dissanayake et al 2022;Senior et al 2022). This period was characterised by climatic fluctuations, and associated fluctuations in sea level (Byrne et al 2011;Chapple et al 2011a;Haines et al 2014).…”

“…Our study, combined with the results from Haines et al (2014), indicates that the glossy grass skink is a single widespread, but genetically variable, species. This is because the level of genetic divergence observed in the species was less than, or equivalent to, the level of intraspecific divergence reported for a range of other Australian skink species (Chapple et al 2004(Chapple et al , 2005(Chapple et al , 2011a(Chapple et al , 2011bSenior et al 2022). Although some degree of morphological variation was evident within the glossy grass skink, there were no consistent morphological differences among the seven genetic lineages in the species.…”

“…Overall, our genetic data might indicate that the glossy grass skink may not disperse across fragmented landscapes, and therefore habitat loss and fragmentation may result in decreased connectivity and genetic diversity within the species (e.g. Crain et al 2008;Dixo et al 2009;Haines et al 2014;Senior et al 2022). However, further work involving more detailed sampling within populations and across the species range, along with additional nuclear loci, would be required to confirm this result.…”

“…The glossy grass skink, and other Pseudemoia species, tend to inhabit areas with high precipitation (Hutchinson and Donnellan 1992;Haines et al 2014), and consequently drying due to climatic oscillations may present geographic www.publish.csiro.au/pc Pacific Conservation Biology 30 (2024) PC23037 boundaries to populations (Byrne et al 2011;Chapple et al 2011a;Bryant and Krosch 2016). In particular, an east-west split in Victoria is common in many skink species, and is likely due to historical volcanic activity (Chapple et al 2005;Senior et al 2022). Additionally, alpine populations are often separate from nearby lowland populations due largely to climatic and resource variation (Chapple et al 2005(Chapple et al , 2011a.…”

Habitat loss and degradation reduce the abundance of the glossy grass skink, Pseudemoia rawlinsoni

“…Nevertheless, reptiles that are dependent on wetland, or wetland-adjacent vegetation may be of particular conservation concern given that much of the landscape between wetlands has been cleared of connecting habitat. For example, the endangered swamp skink (Lissolepis coventryi) has suffered declines in population size and genetic diversity associated with fragmentation of its preferred dense wetland vegetation (Senior et al 2022). Small ectotherms such as lizards generally have poor dispersal abilities, and thus make excellent models for evaluating the effects of habitat loss on populations at fine scales (Olsson and Shine 2003;Dubey and Shine 2010;Ackley et al 2015;Doherty et al 2020).…”