From speciation to introgressive hybridization: the phylogeographic structure of an island subspecies of termite, Reticulitermes lucifugus corsicus.
BACKGROUND
Although much research has been carried out into European Reticulitermes taxonomy in recent years, there is still much discussion about phylogenetic relationships. This study investigated the evolution from intra- to interspecific phylogeny in the island subspecies Reticulitermes lucifugus corsicus and threw new light on this phenomenon. An integrative approach based on microsatellites and mitochondrial and nuclear DNA sequences was used to analyze samples taken from a wide area around the Tyrrhenian sea and showed how the subspecies evolved from its origins to its most recent form on continental coasts.


RESULTS
According to mitochondrial phylogeny and molecular clock calculations, island and continental taxa diverged significantly by vicariance in the Pleistocene glacial period. However, more recently, numerous migrations, certainly human-mediated, affected the structure of the populations. This study provided evidence of direct hybridization and multiple introgressions which occurred in several hybrid areas. Analysis using STRUCTURE based on microsatellite data identified a population in Provence (France) which differed considerably (Fst = 0.477) from populations on the island of Corsica and in Tuscany in the Italian peninsula. This new population, principally distributed in urban areas, is highly heterogeneous especially within the ITS2 regions where homogenization by concerted evolution does not appear to have been completed.


CONCLUSIONS
This study provides an unusual picture of genetic interaction between termite populations in the Tyrrhenian area and suggests that more attention should be paid to the role of introgression and human impact on the recent evolution of European termites.
Lefebvre
Thomas
T
I.R.B.I., CNRS UMR 6035, Université François Rabelais de Tours, Faculté des Sciences et Techniques, Parc de Grandmont, 37200 Tours, France. thomas.lefebvre@bondy.ird.fr
Châline
Nicolas
N
Limousin
Denis
D
Dupont
Simon
S
Bagnères
Anne-Geneviève
AG
D000818:Animals; D019143:Evolution, Molecular; D005163:Factor Analysis, Statistical; D049810:Genetic Speciation; D049750:Genome, Insect; D005843:Geography; D006239:Haplotypes; D006824:Hybridization, Genetic; D020049:Isoptera / Q000145:classification / Q000235:genetics*; D007558:Italy; D018895:Microsatellite Repeats; D010802:Phylogeny; D017422:Sequence Analysis, DNA