Landscape Genetics of Southern populations of Anastrepha fraterculus

FERREYRA, L.I.; FREILIJ, D.; VILARDI, J.C.; GÓMEZ CENDRA, P.V.

BOGOTÁ

Congreso; Congreso Americano de Moscas de la Fruta ? 10 Reunión TWWH; 2020

Grupo de Trabajo en Moscas de la Fruta del Hemisferio Occidental - Tephritids Workers of Western Hemisphere (TWWH)

Anastrepha fraterculusis a complex of cryptic species involving at least eight differentbiological entities. In Argentina, information from multiple sources supports the occurrence of asingle morphotype, ?Brazilian-1?, which is present in the sub-tropical Northeast and Northwestregions, where the weather is warm and humid. A study previously conducted in our laboratory onthe variability of a 417 bp mitochondrial COII gene fragment found no significant associationbetween haplotypic variability and geographic distribution. The method applied was Templeton´sNested Clade Phylogeographic Analysis, which can provide very specific conclusions about thephylogeographic hypotheses, but is not model-based and its reliability and quantification ofuncertainty has been questioned. In the present work we re-analyzed those data applying a model-based Bayesian Phylogeographic and Ecological Clustering approach which assumes thatpopulation substructure is the result of individual migration events, infers geographical populationclusters, and admits a model for the evolutionary history. The analysis was based on the mt DNAfragment mentioned above. Sequences were modeled under the coalescent model, includinggeographical information and environmental covariables in order to identify population clusters asa result of migration. Seven Argentinian and one South Brazilian populations were sampledinvolving 28 individuals. These populations belong tofive ecoregions grouped in three biomes. Sixenvironmental variables meaningful for modeling A. fraterculusdistribution were included ascovariates: (1) mean temperature of warmest quarter, (2) mean temperature of coldest quarter, (3)precipitation of wettest quarter, (4) precipitation of driest quarter, (5) average solar radiation, and(6) average normalized difference vegetation index (NDVI). Demographic changes were evaluatedby a mismatch distribution plot, the raggedness index (rg), the neutrality Tajimas´D (TD) and Fu´sFstests. Taken as a whole these tests rejected the assumption of neutral evolution and constantpopulation size. The population growth parameters estimated from coalescent trees simulated byMCMC procedures suggested a population expansion starting 2500 years before present. A totalof 18 different haplotypes were identified. The Bayesian phylogeographic analysis including theenvironmental variables identified 2 clusters. Cluster 1 involves five haplotypes only found inPosadas (Argentina) and cluster 2 includes 12 haplotypes found in different populations. Theremaining haplotype may belong to clusters 1 or 2 with the same probability. The ecologicalclustering also indicated that the distribution of the environmental covariables differs betweenclusters. The analysis supports that the most probable number of migration events was 1 and themost likely ancestral location is Posadas. From this area A. fraterculuswould have expandedsouthwards and westwards, originating the populationsof cluster 2. The approach used in thepresent work might be applied to a wider range of populations and a larger DNA region to elucidatethe relationships and expansion routes of A. fraterculus.