Johannesson k a (5 risultati)

Kartoniert-O. Condizione: Gut. 1. Auflage.. 64 Seiten, 8°, mit reichh.Fotomat., in engl. Sprache, gutes Exemplar. P21596_Werften Sprache: Englisch Gewicht in Gramm: 400.

Galician exposed shore populations of the direct developing periwinkle Littorina saxatilis are strikingly polymorphic, with an ornamented and banded upper shore form and a smooth and unbanded lower shore form. Intermediates between the two pure forms occur in a narrow mid shore zone together with the parental forms. We have previously shown that the two pure forms share the same gene pool but that mating between them is non-random. This is due to a non-random microdistribution in the zone of overlap, and also to assortative mating. In this study we present data which show that intermediate (hybrid) females mate less often than pure females in micropatches dominated by either of the pure forms, but not in micropatches in which the two pure forms are equally common. Thus, sexual fitness in intermediate females depends on the frequency of both pure morphs. Furthermore, sexual selection against intermediate females also varies with the densities of snails within each micro patch. The biological mechanisms which may explain this particular reduction of female hybrid fitness are discussed. Assortative mating between the pure morphs is sometimes almost complete, while both morphs do not mate the intermediates assortatively. In the light of this, sexual selection against intermediate females may contribute considerably to restrict gene flow between the pure forms. 6 pp., 2 tabs, 4.…

geheftet. Condizione: Sehr gut. S.64; mit reichh.Fotomat., 22 cm Zustand: sehr gut - neuwertig F-R8055 Wenn das Buch einen Schutzumschlag hat, ist das ausdrücklich erwähnt. Rechnung mit ausgewiesener Mwst. Sprache: Englisch Gewicht in Gramm: 175.

Paperback. Condizione: Good +. First Edition. viii, 249 pp. Maps. Tables. FAO Fisheries Technical Paper 240. Label removed from spine, leaving mark. Light wear otherwise. Includes references and recommended reading. Echo sounding in fishing.

geheftet. Condizione: Sehr gut. 1. Aufl. 64 Seiten; mit reichh.Fotomat., Zustand: sehr gut - neuwertig F-R8056 Wenn das Buch einen Schutzumschlag hat, ist das ausdrücklich erwähnt. Rechnung mit ausgewiesener Mwst. Sprache: Deutsch Gewicht in Gramm: 160.