Climate driven patterns shape clusters of co-occurring ticks and vertebrates in the Western Palearctic-Tropics.

Abstract

The assembly of parasite communities is driven by the intricate interplay between geography, climate and host communities, all of which define the range of tick species. Understanding these processes is necessary for uncovering the dynamics behind the circulation of tick-borne pathogens. In this study, we identify traits that define endemicity and ß-diversity patterns in interacting vertebrate and tick communities, based on the distributions of 82 species of ticks and 121 genera of vertebrates across a region that spans the Western Palearctic and the Tropics. Both ß-diversity and endemism exhibit considerable variation between climate regions, with maxima in the Rift Valley, South Africa, and a narrow oceanic band in Namibia. ß-diversity is high in sub-Saharan Africa, and lower in the Western Palearctic. Four chorotypes of co-occurring ticks were identified. Environmental and spatial niche sharing among chorotypes is high, except for certain tick species distributed over the Western Palearctic. Chorotypes display low values of hosts phylogenetic diversity, denoting a low impact of the occurrence of vertebrates on the delineation of chorotypes. Of importance, some ticks that overlap their environmental niche use phylogenetically distant hosts. Chorotypes aid in understanding biodiversity patterns and interactions among hosts and ticks. They are proposed as a framework for investigating the occurrence and spread of tick-borne pathogens. This framework allows a consistent structure for mapping and exploring critical vector-hosts associations in large areas, that could drive key epidemiological patterns of tick-borne diseases.