ADAPTATIVE CHARACTER OF A ROBERTSONIAN FUSION IN CHROMOSOMES OF THE FISH GOBIUS-PAGANELLUS (PISCES, PERCIFORMES)

Four new karyomorphs have been detected in extending the study of Gobius paganellus'’ chromosomal polymorphism to a distance of about 1000 km along the south-east Spanish coast. These new morphs are equivalent to others previously found (Thode et al., 1985), in which a second chromosome fusion (F', by Giles et al., 1985) is present. Frequency distribution of F' in the sampled area shows significant differences between both the western and eastern zones, suggesting that this rearrangement has an adaptative character related to the interaction of Mediterranean and Atlantic environmental conditions. © 1990, The Genetical Society of Great Britain.