THE HATCHING PATTERN OF BRANCHIPODOPSIS WOLFI (CRUSTACEA: ANOSTRACA): PHENOTYPIC PLASTICITY, ADDITIVE GENETIC AND MATERNAL EFFECTS
T.I.M. Van Dooren, L. Brendonck
Abstract:
We estimated quantitative genetic effects on the hatching pattern in the fairy shrimp Branchipodopsis wolfi, as part of a study on live history variation within and among metapopulations of that species in south-eastern Botswana. The results are presented of a breeding experiment (partial diallel cross breeding design) in which we studied reaction norms for hatching at different temperatures and after successive hydration/dehydration cycles. Only hatching at 20C and after the first dry period was sufficiently high (on average 11.6%) to allow a quantitative genetic analysis. We found significant additive genetic effects on hatching probability. We could not demonstrate dominance interaction effects nor epistasis effects. The hatching probability of cysts in a clutch shows a positive correlation with the age of the mother at the moment she shed that clutch. Three possible explanations are given for the evolutionary significance of this pattern: i) mothers use their own age as a predictor for successful reproduction of their offspring at the following inundation, ii) mortality increases among cysts from mothers of increasing age or iii) embryos from younger mothers suffer higher mortality at emergence.
(Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Wilrijk), Belgium)