PHYLOGEOGRAPHY OF THE NATTERJACK TOAD BUFO-CALAMITA IN BRITAIN - GENETIC DIFFERENTIATION OF NATIVE AND TRANSLOCATED POPULATIONS

The natterjack toad Bufo calamita is rare in Britain, which is at the northwestern edge of its biogeographical range. We investigated the le vel of genetic differentiation amongst almost all (34 out of 38) of th e surviving British populations of this species, and among six new pop ulations established by translocations during the 1980s. For eight mic rosatellite loci, allele sizes and frequencies were analysed using sam ples from each of these populations. The populations clustered into th ree robustly differentiated groups, each of which corresponded with a geographical region (east/southeast England, Merseyside and Cumbria). The Cumbrian populations showed a further weak geographical substructu ring into northern and southern clades. The populations in south Cumbr ia were genetically more diverse than those in any of the other region s, as judged by the mean numbers of alleles per locus and the mean het erozygosity estimates. The translocated populations clustered close to their founders and, with one exception, did not differ significantly with respect to mean allele numbers, heterozygosity or polymorphism le vel. However, significant genetic differentiation las measured by unbi ased R-ST was found between all but one of the founder-translocation p airs. The implications of this phylogeographic study for the future co nservation of B. calamita in Britain are discussed.