C. Calmet et al., Is it worth eradicating the invasive pest Rattus norvegicus from Molene archipelago? Genetic structure as a decision-making tool, BIODIVERS C, 10(6), 2001, pp. 911-928
Genetic variability and structure were estimated by microsatellite analysis
at 7 loci in brown rat populations (Rattus norvegicus) from the Iroise ins
ular complex and neighbouring mainland (Brittany, France). Island genetic d
iversity is lower than on the mainland and a highly significant positive co
rrelation was found between mean heterozygosity and the logarithm of island
area, which is consistent with theoretical expectations. Rattus norvegicus
populations are substructured at a kilometric scale, both on the islands a
nd on the mainland. Intra-island structuration is extremely high, suggestin
g that no effective migration occurs between islands or with the mainland.
Historical and genetical evidence suggest that R. norvegicus was introduced
independently on Ouessant and Molene archipelago, with a low and a high fo
under effect respectively. These results are discussed in terms of recoloni
zation probability of islands that have been cleared of R. norvegicus, whic
h illustrates the usefulness of genetic markers in determining parameters o
f interest to the conservation biologist.