To change or not to change sex : A comparison between two Ophryotrocha species (Polychaeta)
1991 (English)In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 5, no 2, 128-135 p.Article in journal (Refereed) Published
The polychaete Ophryotrocha puerilis is a male-to-female sex-changer, whereas O. labronica has separate sexes throughout life. In other respects the two species are remarkably similar: they occur in the same habitat, they look the same, they eat the same things, and in some O. labronica populations sex-changers can actually be found. The size-advantage hypothesis predicts that in O. puerilis males should not benefit reproductively from a size increase as much as males in O. labronica: hence O. puerilis but not O. labronica males should change to the female sex at a certain size. I experimentally compared reproductive success at different body sizes between the two species. In isolated male-female pairs reproductive rate increased significantly with female body size but not with male body size, and this pattern was the same in both species. Hence male fecundity per se cannot account for the difference in reproductive type between the two species. In other experiments I investigated if larger males gained access to more females because they were superior competitors for mates or were preferred by females, compared to small males. In O. puerilis the combined effect of these two factors conferred no size advantage to the males, whereas in O. labronica larger males acquired more females than did smaller males. Hence interactions among males and females, in accordance with the size-advantage hypothesis, can explain why sex change is maintained in O. puerilis, and why separate sexes are maintained in O. labronica.
Place, publisher, year, edition, pages
1991. Vol. 5, no 2, 128-135 p.
Sex change, sequential hermaphrodition, size-advantage, hypothesis, gonochorism
IdentifiersURN: urn:nbn:se:uu:diva-126436DOI: 10.1007/BF02270829ISI: A1991FK60600004OAI: oai:DiVA.org:uu-126436DiVA: diva2:324068