caa a22 4500 386400032 CHVBK 20180307112155.0 cr unu---uuuuu 161130e198904 xx s 000 0 eng 10.1017/S0031182000062156 doi S0031182000062156 pii (NATIONALLICENCE)cambridge-10.1017/S0031182000062156 Harris P.D. Department of Zoology and Comparative Physiology, University of Birmingham, P.O. Box 363, Birmingham B15 2TT Interactions between population growth and sexual reproduction in the viviparous monogenean Gyrodactylus turnbulli Harris, 1986 from the guppy, Poecilia reticulata Peters [Elektronische Daten] [P.D. Harris] Mating was observed in populations of Gyrodactylus turnbulli from guppies. Copulation took place between older (post-1st birth) flukes and resulted in the insemination of spermatozoa into the seminal receptacle. New-born flukes, and flukes which had only recently given birth for the first time (in which the penis was absent or developing), were never inseminated. Flukes were promiscuous, copulating with several partners in succession. The occurrence of mating was related to the size, age and crowding of the G. turnbulli population, taking place most frequently when the parasites were most densely crowded upon the peduncle of the fish on days 5 and 6 of the infection. Maximum population size was positively correlated with the number of flukes initiating an infection. As a result, mating began earlier, and continued for longer in populations founded by several parasites rather than those begun by single flukes. These observations are discussed with respect to the population biology of G. turnbulli: it is likely that sexual and asexual reproduction alternate, with sex being important only during phases of epidemic population growth. The significance of sex in gyrodactylids is discussed, and the potential importance of continuous sexual reproduction in G. turnbulli infections on cultivated guppies is noted. Copyright © Cambridge University Press 1989 Gyrodactylus turnbulli nationallicence population growth nationallicence sexual reproduction nationallicence Poecilia reticulata nationallicence Parasitology Cambridge University Press 98/2(1989-04), 245-251 0031-1820 98:2<245 1989 98 PAR https://doi.org/10.1017/S0031182000062156 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0031182000062156 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Harris P.D. Department of Zoology and Comparative Physiology, University of Birmingham, P.O. Box 363, Birmingham B15 2TT NATIONALLICENCE 773 0- Parasitology Cambridge University Press 98/2(1989-04), 245-251 0031-1820 98:2<245 1989 98 PAR CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge