Impact of Climate Change on Reptiles (Order Testudinea) in Pakistan: current and future trends

Abstract

Pakistan, located in South Asia between the Palearctic, Ethiopian, and Oriental biogeographic realms, possesses diverse landscapes including mountains, plains, deserts, arid regions, and the Arabian Sea coast, with climatic extremes such as floods, droughts, and monsoon variability shaping its biodiversity. Reptiles, constitute nearly one-fourth of known vertebrate fauna, and are highly influenced by climatic and geographic factors, thus making distribution and population densities dependent on temperature and other environmental gradients. Pakistan hosts around 170 living Reptilian species where Testudines (turtles and tortoises) consisted of fifteen spp. inhabiting freshwater, marine, and terrestrial ecosystems across tropical and subtropical regions and considered world’s most threatened group because of habitat loss, illegal trade, diseases and climate change. The present analysis evaluated the impact of temperatures, moisture and changing weather (global warming) on three vulnerable species of Pakistan: Caretta caretta, Geochelone elegans, and Lepidochelys olivacea (IUCN, 2019). A total of 136,888 occurrence records of last 40 years from 1980–2019 were obtained from global biodiversity information facility (GBIF) and 19 climatic predictors taken from WorldClim 1.4 database using carbon emission level (RCP 4.5) for future projections of 2050 through generalized linear model (GLM) and maximum entropy (MaxEnt) models in R program. Results indicated a distribution range shifts for all three species: Caretta caretta was mainly affected by climatic variable (BIO-09) mean temperature of driest quarter and (BIO-08) mean temperature of wettest quarter, Geochelone elegans with a slight extinction risk of (-0.5%) was affected with BIO-I mean annual temperature and BIO-02 mean diurnal range while Lepidochelys olivacea was affected by BIO-19 precipitation of coldest quarter, BIO-02 mean diurnal range and BIO-08 mean temperature of wettest quarter. Overall, the study projected that future climate change under RCP 4.5 would significantly modify the geographic distribution and habitat suitability of vulnerable species of Reptiles in Pakistan by 2050.