Genetic testing of GIS-based models of dispersal in Triturus newts
This study aims to reconstruct the dispersal routes of the great-crested newt (Triturus cristatus) in a moving hybrid zone. It is known from field studies that this species has migrated into areas that were previously strongholds of the marbled newt (Triturus marmoratus). This is a natural process, but it is almost certainly expedited by recent, anthropogenic changes to the environment.The study site, near Mayenne, western France, has been the site of agricultural reform resulting in field enlargement and removal of the hedgerows. Hedgerow clearance has been to the advantage of T. cristatus and to the detriment of T. marmoratus. The use of GIS (geographical information systems, including satellite imaging), aerial photographs and historical data, combined with an understanding of their habitat preferences, has led us to hypothesise that T. cristatus invaded from the east of France along flat, unforested land. From the results of our research it will be possible to test the invasion hypothesis by looking at the genetic flow between populations in a network of ponds. If this can be achieved successfully then the study should have far reaching consequences in showing that genetic and GIS analyses can be successfully combined and applied in the conservation of natural populations of plants and animals.
During this study we have isolated and characterised numerous tetranucleotide microsatellite markers from T. cristatus, from which a set of eight highly polymorphic loci has been selected for use in our population studies. Cross-species amplification is possible in T. marmoratus, and has already been used to distinguish larvae of the two species and their hybrids. One-thousand two-hundred T. cristatus individuals from 45 ponds throughout the study site have been genotyped using an ABI Prism 377 DNA Sequencer. The data are currently being analysed and the results should be available in the near future.
The study has been funded by the Natural Environment Research Council (http://www.nerc.ac.uk).
1997-2000 Andy Krupa (A.Krupa@Sheffield.ac.uk)
Dr. J.W. Arntzen, University of Porto, Portugal (joint Principal Investigator)
Robert Jehle, University of Vienna, Austria
Elsa Froufe, University of Porto, Portugal
Thanks to Dr. J.W. Arntzen and Robert Jehle for supplying the newt images.
Erratum: Krupa et al. (2002) Microsatellite loci in the crested newt (Triturus cristatus), and their utility in other newt taxa.Conservation Genetics, 3, 87-89.
Krupa AP, Jehle R, Dawson DA, Gentle LK, Gibbs M, Arntzen JW, Burke T (2002) Microsatellite loci in the crested newt (Triturus cristatus), and their utility in other newt taxa. Conservation Genetics, 3, 87-89.
Jehle R & Arntzen JW (2002) Review: Microsatellite markers in amphibian conservation genetics, Herpetological Journal, 12, 1-9.
Arntzen JW and GP Wallis (1999) Geographic variation and taxonomy of Crested newts (Triturus cristatus superspecies): morphological and mitochondrial DNA data. Contributions to Zoology, 68 (3), 181-200.
Arntzen JW (1996) Parameters of ecology and scale integrate the gradient and mosaic models of hybrid zone structure in Bombina toads and Triturus newts. Israel Journal of Zoology, 42, 111-119.