A Parasite Reveals Cryptic Phylogeographic History of Its Host: The Colonization of the Western Mediterranean Islands

This study compares the colonisation patterns of the field mouse Apodemus sylvaticus (Muridae) and its parasite Heligmosomoides polygyrus (Heligmosomoidea) in 8 Western Mediterranean islands. Respectively 690 bp and 501 bp of the mitochondrial cytochrome b gene were sequenced in 44 H. polygyrus and 49 A. sylvaticus. The results reveal the congruence between both species’ insular Mediterranean colonisation and highlight the role of biological “magnifying glass” of the parasite in precising the continental origin of insular wood mice: both species colonised the Balearic islands and Porquerolles from Spain or Southern France, while Elba, Sardinia and Sicily were colonized from Central-South Italy and Corsica from northern Italy, and Crete from Greece. Finally, Sicily should be considered as a “hot spot” of intraspecific genetic biodiversity.