Niche modeling for the genus Pogona (Agamidae: Squamata) in Australia: predicting past (late Quaternary) and future (2070) occurrence

Background/Question/Methods: As the climate warms, many species of reptiles are at risk of habitat loss and ultimately extinction. Past, current, and future distribution predictions of several lizard species have already been modeled using MaxEnt, incorporating climatic variables related to temperature and precipitation. In this study, we examine the genus Pogona (commonly known as the bearded dragon), and predict where there is currently suitable habitat and where suitable areas may have shifted in the past or may shift in the future. Georeferenced occurrence records were obtained from the Global Biodiversity Information Facility, climate variables (bioclimatic, describing temperature and precipitation) were obtained from WorldClim, and a vegetation index was obtained from AVHRR satellite data. Matching climate variables were downloaded for three different past time periods (Last Interglacial, mid-Holocene, and Last Glacial Maximum) and two different future projections (RCPs 2.6 and 8.5). Variable resolution was 1 km² and occurrence records were rarefied to match. MaxEnt produced accuracy metrics, response curves, logistic thresholds, and probability surfaces. A 10% maximum occurrence record exclusion threshold was applied to each probability surface to delineate presence/absence predictions.

Results/Conclusions: In the 2070 future predictions, both models show similar results; however, the model produced using the 2070 RCP 8.5 climate change projection is more expansive in areas of potential habitat gain and loss. In the future P. henrylawsoni and P. microlepidota will gain habitat, while the other four species will primarily experience habitat loss. Based on the model results Pogona henrylawsoni emerged between the mid-Holocene and current, and P. microlepidota emerged between the Last Glacial Maximum and the mid-Holocene. The origination of these two species along with the predicted late Quaternary distributions for P. barbata, P. minor, P. nullarbor, and P. vitticeps are conservative and should be compared to the Pogona fossil record, which is currently not well known. Pogona nullarbor is the only species analyzed to potentially be considered vulnerable in the present since they already have a restricted range, and both future models predict additional habitat loss. A conservation plan may need to be considered in the future for Pogona nullarbor based on model results. Additionally, if greenhouse gas emissions continue to rise, P. barbata, P, minor, and P. vitticeps could become vulnerable or threatened.