Marked Genetic Differentiation between Western Iberian and Italic Populations of the Olive Fly: Southern France as an Intermediate Area.

摘要

The olive fly, Bactrocera oleae, is the most important pest affecting the olive industry, towhich it is estimated to cause average annual losses in excess of one billion dollars. As withother insects with a wide distribution, it is generally accepted that the understanding of B.oleae population structure and dynamics is fundamental for the design and implementationof effective monitoring and control strategies. However, and despite important advances inthe past decade, a clear picture of B. oleae's population structure is still lacking. In the Mediterraneanbasin, where more than 95% of olive production is concentrated, evidence fromseveral studies suggests the existence of three distinct sub-populations, but the geographicallimits of their distributions, and the level of interpenetration and gene flow among themremain ill-characterized. Here we use mitochondrial haplotype analysis to show that one ofthe Mediterranean mitochondrial lineages displays geographically correlated substructureand demonstrate that Italic populations, though markedly distinct from their Iberian and Levantinecounterparts are more diverse than previously described. Finally, we show that thisdistinction does not result from extant hypothetical geographic limits imposed by the Alps orthe Pyrenees nor, more generally, does it result from any sharp boundary, as intermixing isobserved in a broad area, albeit at variable levels. Instead, Bayesian phylogeographic analysissuggests the interplay between isolation-mediated differentiation during glacial periodsand bi-directional dispersal and population intermixing in the interglacials has played amajor role in shaping current olive fly population structure