A. Guiller et al., Evolutionary history of the land snail Helix aspersa in the Western Mediterranean: preliminary results inferred from mitochondrial DNA sequences, MOL ECOL, 10(1), 2001, pp. 81-87
Intraspecific phylogeographic methods provide a means of examining the hist
ory of genetic exchange among populations. As part of a study of the histor
y of Helix aspersa in the Western Mediterranean, we performed a phylogeneti
c analysis based on partial sequences of the mitochondrial large ribosomal
subunit (16S) gene. Our samples include 31 H. a. aspersa populations from N
orth Africa previously investigated for anatomical and biochemical characte
rs. To clarify subspecific relationships, three individuals of the subspeci
es H. a. maxima were also studied. The molecular phylogeny inferred agrees
largely with previous results, in splitting H. a. aspersa haplotypes into a
n eastern and a western group. H. a. maxima haplotypes form a third lineage
arising before the H. a. aspersa groups. Divergence times estimated betwee
n the lineages suggest that dispersal during Pleistocene glaciation and vic
ariance events due to Pliocene geological changes in the western Mediterran
ean may both have played a significant part in the establishment of the pre
sent range of H aspersa.