Two populations of Tisbe holothuriae, coming from marine (Banyuls-sur-mer) and brackish waters (Sigean), have been analyzed before and after progressive inbreeding. It has been shown that an increase of the homozygosity due to inbreeding determines in both populations a progressive depression of survival, fecundity, mean generation time and intrinsic rate of natural increase. The inbreeding depression is higher in the marine population. The concealed genetic variability, estimated on the basis of survival values, demonstrates a higher genetic load in the marine population. The hypothesis is advanced that the genetic variability in the population from Sigean, subjected to extreme variability in time of both chemical and physical factors, is lower than in the population from Banyuls.
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Con il contributo del Ministero per i Beni e le Attività Culturali