A preliminary investigation of allozyme genetic variation and population geographical structure in Aphanius fasciatus from Italian brackish-water habitats |
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Authors: | F. Maltagliati |
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Affiliation: | Dipartimento di Scienze dell'Uomo e dell'Ambiente, Via A. Volta 6, 1-56126 Pisa, Italy |
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Abstract: | A total of 150 individuals from Aphanius fasciatus from coastal brackish-water habitats was analysed by allozyme electrophoresis to collect data on its genetic variation. From 22 enzymes, 43 putative enzyme-coding loci were resolved, 12 of which were polymorphic at P0·99 level. Only one of the 31 probability tests showed a significant departure from the Hardy-Weinberg equilibrium. Aphanius fasciatus showed low levels of genetic polymorphism, with expected heterozygosity values ranging from 0·027 (S.E.=0·013) to 0·064 ( s.e. =0·023). Nei's genetic distances between populations ranged from 0·002 to 0·042. Weir & Cockerham F -statistics showed high levels of genetic heterogeneity among populations (jackknifed θ=0·302, s.e. =0·045) and estimates of N m were < 1, indicating restricted gene flow. Significant positive correlation between genetic distance and geographical distance matrices, detected by Mantel's test ( g =1·941; P 0·001), is consistent with the prediction that the species is genetically structured by isolation-by-distance. |
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Keywords: | Aphanius fasciatus brackish-water habitats allozymes genetic variation genetic distance gene flow isolation-by-distance |
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