Post-Doctoral Associate University of Arizona Tucson, Arizona
The whitefly Bemisia tabaci cryptic/sibling species group consists of important pests and plant virus vectors corresponding to geographically structured phylogenetic clades. Here, the mitochondria cytochrome oxidase (mtCOI) gene sequences from individual whiteflies (n= 1,923) were used to infer a global phylogeny of the B. tabaci cryptic/sibling species group, and the extent of diversity within the cryptic species was estimated based on corrected nt distances with a 12.5% species threshold. Using matrix correlation and niche modeling methods, respectively, whitefly ‘occurrence’ records were superimposed to determine if phylogenetic breaks were structured based on geographical affiliations or sharp transitions across environmental gradients i.e. indicative of geographic isolation. To determine if intra-clade genetic variation could be explained by spatial distribution, the intra-clade divergence estimates were compared to the geographic distances of the members of the clade using a simple mantel test. To account for potential influence by environmental factors a partial mantel test that evaluated fourteen agro-environmental variables was carried out. Finally, the climatic suitability, as a potential driver of diversification of endemic B. tabaci clades, was assessed by ecological niche modelling that considers environmental-, ecological-, and agriculture-related factors that might have been influenced by ecological processes that in turn may delimit the distribution and phenotypic plasticity within the B. tabaci cryptic species. Distance analysis delineated fourteen lineages that grouped within and/or basal to recognized major species clades (delineated by analysis of 2184 nuclear genes) from the American Tropics, Asia, Asia-Pacific-Australia, North Africa-Mediterranean-Middle East, Sub-Saharan Africa, and ‘undefined’ sweet potato-Uganda, and Italian highlands-T mitotype.
