Evolutionary history of the land snail Helix aspersa in the Western Mediterranean: preliminary results inferred from mitochondrial DNA sequences

Abstract

Intraspecific phylogeographic methods provide a means of examining the history of genetic exchange among populations. As part of a study of the history of Helix aspersa in the Western Mediterranean, we performed a phylogenetic analysis based on partial sequences of the mitochondrial large ribosomal subunit (16S) gene. Our samples include 31 H. a. aspersa populations from North Africa previously investigated for anatomical and biochemical characters. To clarify subspecific relationships, three individuals of the subspecies H. a. maxima were also studied. The molecular phylogeny inferred agrees largely with previous results, in splitting H. a. aspersa haplotypes into an eastern and a western group. H. a. maxima haplotypes form a third lineage arising before the H. a. aspersa groups. Divergence times estimated between the lineages suggest that dispersal during Pleistocene glaciation and vicariance events due to Pliocene geological changes in the western Mediterranean may both have played a significant part in the establishment of the present range of H. aspersa.

Genetic variation within African spiny-tailed lizards (Agamidae: Uromastyx) estimated using mitochondrial DNA sequences

“…However, much less is understood concerning the evolutionary history of North African fauna during this period. North Africa experienced alternate humid and arid periods that appeared to affect many terrestrial species, from snails (Guiller et al, 2001) to mammals (Cosson et al, 2005). Of the reptiles studied, Agama (Brown et al, 2002), Acanthodactylus (Harris et al, 2004a), Blanus (Vaconcelos et al, 2006), Lacerta perspicillata (Harris et al, 2003) and Tarentola (Harris et al, 2004b) all show deep phylogenetic divisions, and the same is demonstrated here in U. acanthinura.…”

The snails the dinosaurs saw: are the pleurocerid populations of the Older Appalachians a relict of the Paleozoic Era?

“…However, double-digit values of % sequence divergence within molluscan populations, such as those shown in Figs 3 and 4, are not entirely unprecedented. The phenomenon has been reported within numerous populations of land snails (Thomaz et al 1996, Goodacre and Wade 2001, Guiller et al 2001, Haase et al 2003 and in the special case of doubly-uniparental inheritance in bivalves (Rawson …”

Early phases of a successful invasion: mitochondrial phylogeography of the common genet (Genetta genetta) within the Mediterranean Basin

“…As a consequence, we expect that at least some dating events proposed for the recently introduced populations across the Mediterranean Basin are likely overestimated. It is thus especially surprising that those estimates that predated by far evidences of human crossing of the Strait of Gibraltar or fossil records were not envisaged under the light of these expected estimation biases and limitations (Guiller et al 2001;Libois et al 2001;Michaux et al 2003;Brandli et al 2005;Cosson et al 2005). Recent methods that calculate simultaneously times of divergence, population sizes and migration rates, were designed to circumvent this bias (e.g.…”