Environmental niche modeling for some species of the genus Anthrax Scopoli (Diptera: Bombyliidae) in Egypt, with special notes on St. Catherine protected area as a suitable habitat

Abstract

The genus Anthrax Scopoli is a well-known genus of bee flies, with 16 species recorded from Egypt, out of about 250 species known worldwide. Six of these species seem to be endangered or threatened (at least in a part of their distribution range) as they disappeared from most of their Egyptian localities which faced severe changes in the floral and faunal composition during the last 50 years. These changes may be attributed to urbanization or modern agricultural activities that caused severe degradation of natural habitats of these species. Maximum entropy (Maxent) modeling was used to predict the potential climatic niches of these six Anthrax species, namely: Anthrax aethiops, Anthrax chionanthrax, Anthrax dentate, Anthrax melanista, Anthrax lucidus, and Anthrax trifasciatus. The Maxent model performed better than random for the six species, with an average test AUC value of 0.95 for A. aethiops bezzii, 0.83 for A. chionanthrax, and 0.98 for A. dentate, 0.86 for A. melanista, 0.96 for A. lucidus and 0.99 for A. trifasciatus. A set of four variables were selected for each species from 19 bioclimatic and 3 topographic variables, based on correlation analyses. The study showed that the current distributions of A. dentata, A. lucidus and A. trifasciatus were largely explained by the altitude, but A. chionanthrax and A. melanista were so far dominated by temperature, whereas on A. aethiops bezzii was strongly related to precipitation variables. St. Catherine protected area showed high habitat suitability for all species except A. lucidus. The suitable habitat for A. trifasciatus was restricted to this protected area, however, future scenarios of climatic changes through the area predict a great degradation in habitat suitability for this species. These results can be used for making powerful conservation management decisions in St. Catherine Protectorate to incorporate these Anthrax spp. in any present or future conservation programs.