Climate Change-Induced Distribution Shifts of Keratin-Feeding Beetle Omorgus (Omorgus) suberosus: Implications for Olive Ridley Sea Turtle Lepidochelys olivacea Conservation

The sea turtle Lepidochelys olivacea (Eschscholtz, 1829) is particularly threatened by egg predation from the invasive beetle Omorgus (Omorgus) suberosus (Fabricius, 1775). However, the impact of global climate change on the distribution and overlap of these species is still poorly understood. Our study aimed to predict the global distributions of O. suberosus and L. olivacea under various climate change scenarios, to examine their distribution overlap and to assess the conservation status of L. olivacea. We analysed a dataset of 2896 O. suberosus records and 15,329 L. olivacea records, using three modelling algorithms: Maximum entropy default (MXD), DOMAIN (DOM) and generalised linear models (GLM) to project their global distributions under the SSP2-4.5 and SSP5-8.5 scenarios. Results revealed shifts in the distribution of O. suberosus by 2100. As temperatures increased, the species expanded its range northward into Europe and North America, while substantial habitat losses occurred in tropical and subtropical regions. Under a mild climate change scenario (SSP2-4.5), the suitable habitat for O. suberosus decreased globally by 9.5%, whereas under a 'business-as-usual' scenario (SSP5-8.5) projected a 20.8% reduction. Our projections indicate that by 2100, L. olivacea will experience significant reductions in suitable coastal habitats under the SSP245 (12.11%) and SSP585 (24.63%) scenarios, with particularly severe losses in northern South America and southern Europe under SSP245 (12.11%). The overlap of O. suberosus and L. olivacea ranges indicates a significant decline. Under the SSP245 scenario for 2081-2100, the overlap area is projected to decrease by 20.66%. The SSP585 scenario forecasts a further reduction of 37.56%. Understanding the interactions between O. suberosus and L. olivacea is vital for guiding field studies and informing conservation strategies. Although our results suggest a reduction in the overlap of these species, the decline in the suitable area of L. olivacea raises concerns. Our findings emphasise the importance of targeted research and strategic management to mitigate the impacts of invasive species and climate change on vulnerable turtle populations globally.