Discordant phylogeographic patterns between the tortoise tick Hyalomma aegyptium and their Testudo graeca hosts

Abstract

Tortoise ticks, Hyalomma aegyptium, are considered so strongly associated with their hosts that they are even used as indirect indicators for them. In such a case, a robust pattern of congruence between host and parasite could be expected, with phylogeographic breaks within the host being reflected in their parasites. We sequenced two mitochondrial partial gene regions (12S rRNA and Cytochrome Oxidase 1) from ticks across northern Africa and Anatolia, and compared patterns of variation with those identified in its main host, Testudo graeca. Two distinct haplogroups were identified, both of which were found distributed across much of northern Africa. This pattern does not reflect the known variation within the host, which has multiple, geographically disjunct subspecies in this region, but rather the major climatic zones. This relationship can be explained by adaptive processes to environmental conditions influenced by the climate, as well as by the spatial structure of the communities of tick potential hosts in larval and nymphal stages. Extensive anthropogenic movement of tortoises may also obscure congruence patterns between H. aegyptium ticks and their hosts.