EFFECT OF CONTROLLED TEMPERATURES ON GAMETOGENESIS IN THE GASTROPODS PHYSA ACUTA (PHYSIDAE) AND BULINUS TROPICUS (PLANORBIDAE) |
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| Authors: | BRACKENBURY, THERESE D. APPLETON, C.C. |
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| Affiliation: | Department of Zoology and Entomology, University of Natal P. O. Box 373, Pietermaritzburg, 3200 South Africa |
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| Abstract: | The effects of a range of constant temperatures on gametogenesiswere investigated in two freshwater snail species which occursympatrically in the Umsin-dusi River, Natal, South Africa,Physa acuta (invasive) and Bulinus tropicus (endemic). Bothwere shown to be simultaneous hermaphrodites with slight protandry.An increase in temperature accelerated the process of gametogenesisbut P. acuta responded more rapidly to these changes than B.tropicus. This, coupled with the greater fecundity and shorterincubation period of P. acuta, gives it a reproductive advantageover the endemic species, providing a possible explanation forthe invasive's success in rapidly repopulating disturbed riverinehabitats. (Received 16 November 1990; accepted 1 May 1991) |
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