Climate change and species distribution: possible scenarios for thermophilic ticks in Romania

Several zoonotic tick-borne diseases are emerging in Europe due to various factors, including changes of the cultural landscape, increasing human populations, variation of social habits and climate change. We have modelled the potential range changes for two thermophilic tick species (Hyalomma marginatum and Rhipicephalus annulatus) by use of MaxEnt® and 15 climatic predictors, taking into account the aptitude for future climatic change in Romania. Current models predict increased temperatures, both in the short term (up to 2050) and in the long term (up to 2070), together with possible changes also of the other climatic factors (e.g. precipitation), and may lead to higher zoonotic risks associated with an expansion of the range of the target species. Three different models were constructed (the present, 2050 and 2070) for four representative concentration pathways (RCPs) of greenhouse gas scenarios: RCP2.6, RCP4.5, RCP6, and RCP8.5. The most dramatic scenario (RCP8.5) produced the highest increase in the probable distribution range for both species. In concordance with similar continental-wide studies, both tick species displayed a shift of distribution towards previously cooler areas of Romania. In most scenarios, this would lead to wider ranges; from 9.7 to 43.1% for H. marginatum, and from 53.4 to 205.2% for R annulatus. Although the developed models demonstrate a good predictive power, the issue of species ecology should also be considered.