| Autor: |
SOUTY-GROSSET, C., GRANDJEAN, F., RAIMOND, R., FRELON, M., DEBENEST, C., BRAMARD, M. |
| Zdroj: |
Bulletin Français de la Pêche et de la Pisciculture; January 1997, Vol. 1997 Issue: 347 p677-692, 16p |
| Abstrakt: |
The white-clawed crayfish, Austropotamobius pallipes pallipes, still has a wide-spread distribution in France, but since the last century, populations have declined because of habitat alteration (due to human disturbance) and have been also eliminated by crayfish plague, for which introduced exotic species are a vector. Action plans for the conservation of A. pallipesare urgent and if recovery programmes are to be initiated in France, then it is important to estimate how much genetic variation is partitioned between remaining populations as the species is being currently threatened in all its European distribution. We show how a new molecular marker can be used to study crayfish populations. Mitochondrial DNA (mtDNA) variation in natural populations was examined by restriction fragment length polymorphism analysis in samples taken from fifteen French populations and six European populations representative of three subspecies observed in A. pallipesin order to examine the extent of differentiation between populations. Biogeographic considerations about the genetic distances observed between the three subspecies are made. The study reveals a low level of genetic variation among English, Welsh and most of French populations, corresponding to a genetic stock uniformity among A. pallipes pallipes. The only two French populations exhibiting a high level of intrapopulational genetic variation are in fact mixed samples : the comparison with results obtained in European populations revealed that the first population was composed of the two subspecies A. pallipes pallipesand A. pallipes italicusand the second of A. pallipes italicusand A. pallipes lusitanicus. Results proved that some repopulations, performed in the past from A. pallipes italicusand supposed having failed, have been successful and that the French stock did not correspond to the only subspecies A. pallipes pallipes. A first analysis of genetic variance observed on a regional scale revealed that there was no genetic structure according to basins and could reflect human-mediated movement of crayfish stocks between these basins. Consequently, mtDNA is an essential marker to measure genetic diversity between crayfish populations, to map how the subspecies are partitioned in France and what the importance of each is before any planning crayfish conservation strategies of the native crayfish |
| Databáze: |
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