Divergent environmental preferences and areas of sympatry of tick species in the Amblyomma cajennense complex (Ixodidae)

ESTRADA-PEÑA AGUSTÍN; TARRAGONA EVELINA L.; VESCO UMBERTO; ATILIO J. MANGOLD; ALBERTO A. GUGLIELMONE; SANTIAGO NAVA

INTERNATIONAL JOURNAL FOR PARASITOLOGY

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2014 vol. 44 p. 1081 - 1089

0020-7519

Four species of Neotropical ticks, Amblyomma mixtum, Amblyomma cajennense, Amblyomma tonelliaeand Amblyomma sculptum (formerly included in the catch-all name A. cajennense), have an allopatricdistribution in much of their range, with areas of parapatry for at least two of them. We inferred theabiotic niches of these organisms using coefficients of a harmonic regression of the temperature andthe Normalized Difference Vegetation Index (NDVI, reflecting plant stress) from remotely sensed datafrom MODIS satellites with 0.05 spatial resolution. Combinations of coefficients describing the phenologyof these two variables pointed to divergent niche preferences, compatible with previous events ofvicariance among the species. Amblyomma cajennense has been recorded in areas with small variationsin temperature and NDVI. The remaining species were recorded in areas with large variations. The maximumenvironmental niche overlap was 73.6% between A. mixtum and A. cajennense and 73.5% betweenA. tonelliae and A. sculptum. Projecting these inferences on the geographical space revealed probable areasof sympatry or parapatry between A. mixtum and A. cajennense or between A. tonelliae and A. sculptum, thelatter of which was confirmed with field collections. The A. sculptum distribution overlaps with that ofA. tonelliae in northern Argentina and Paraguay; parapatry occurs at one extreme of the conditions occupiedby both species. Compared with areas of allopatry, sites with both species had consistently lowertemperatures, except for 10?12 weeks during the summer, and higher NDVI values throughout the year.We hypothesise that the overlap between A. tonelliae and A. sculptum resulted from secondary contactbetween populations, with A. sculptum adapting to sites with high water availability to balance highsummer temperatures. Additional surveys of the areas of spatial overlap among these species arenecessary to elucidate the forces driving their evolution and their adaptation to the environment.