Summary: Journal of Animal
© 2004 British
Blackwell Publishing, Ltd.
Low proportions of reproducing hemiclonal females
increase the stability of a sexual parasitehost system
(Rana esculenta, R. lessonae)
H.-U. REYER, M.-O. WÄLTI, I. BÄTTIG, R. ALTWEGG* and B. HELLRIEGEL
Zoological Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
1. The number of reproductive events per lifetime affects all levels of ecological
complexity, including the structure and dynamics of species communities. Here we
investigate a sexual parasitehost system with two water frog species of which one
(Rana esculenta, E) is a hemiclonal hybrid that depends on one of its parental species
(R. lessonae, L) for successful reproduction. Previous theoretical models have shown
that relative fecundities are important for the species composition and stability of this
system, but empirical data from natural mixed LE-populations were lacking.
2. We used three different methods to estimate the proportion of annually reproducing