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Analysis of the population structure of Macrolophus pygmaeus (Rambur) (Heteroptera: Miridae) in the Palaearctic region using microsatellite markers

Sanchez, Juan Antonio, La Spina, Michelangelo, Perera, Omaththage P.
Ecology and evolution 2012 v.2 no.12 pp. 3145
Bayesian theory, Macrolophus, alleles, biogeography, climate change, genetic markers, geographical distribution, glaciation, heterozygosity, introgression, linkage disequilibrium, microsatellite repeats, population genetics, population structure, Balkans, Canary Islands, France, Greece, Italy, Southern European region, Spain, Turkey (country)
Macrolophus pygmaeus (Rambur) (Heteroptera: Miridae) is widely distributed throughout the Palaearctic region. This current geographical distribution may have been influenced by climate change during the last glaciations and the geographical barriers interfering with the dispersal from southern refuges. The aim of this work was to explain the current geographical distribution of M. pygmaeus by investigating the genetic population structure using nine microsatellite markers. Samples of Macrolophus pygmaeus were collected in 15 localities through its Palaearctic range. A sample from a commercial producer was also analysed. Polymorphism was high (13.9 alleles per locus) with a maximum in southern Spain (68 alleles). Istanbul (Turkey) and Nimes (France) had the lowest (0.266) and the highest (0.592) observed heterozygosity (Ho), respectively. There was an increase in Ho from the Canary Islands to Nimes, and a progressive decrease thereafter. A significant correlation was found between the number of alleles and Ho, and the distance of each sample to the easternmost locality (Canary Islands). Significant linkage disequilibrium was observed in the samples from Turkey. FST (0.004 - 0.334) indicated a high population differentiation, with isolation by distance supported by a strong correlation. Bayesian analyses, PCA and UPGMA pointed to three main clusters: (1) Greece and Turkey, (2) Italy and France and (3) southern Iberia and the Canary Islands. The recent evolutionary history of M. pygmaeus is predicted as follows: (1) the reduction of the geographical distribution of the species to the Iberian, Italian and Balkan peninsulas, and possibly southern France, during glaciations and re-colonization of northern Europe from its southern refuges ; (2) The maintenance of high diversity in Iberia and Italy (and possibly southern France) during contraction periods, and bottlenecks in the Balkans; (3) Introgression of the Italian-French lineage in northern Spain, naturally or through trade.