Correlation between male and female reproduction in the subdioecious herb Astilbe biternata (Saxifragaceae)

Genotypic trade-offs between male and female reproduction are commonly assu med in theoretical studies of the evolution of gender specialization. Altho ugh these trade-offs are supported by higher seed production of females tha n hermaphrodites in natural populations of gynodioecious species, compariso ns between male and female reproductive allocation among hermaphrodite indi viduals under controlled conditions are rare. We assessed phenotypic and ge notypic correlations between stamen and fruit production in fruiting males of the near-dioecious herb Astilbe biternata. In the field, we found a sign ificant negative phenotypic correlation between stamen production and fruit production within individuals that produced both stamens and fruit as well as higher fruit set in females than fruiting males. The negative correlati on between fruit and stamen production that was observed in the field was a lso apparent across clonally propagated genotypes. These results suggest th at negative genetic correlations between male and female reproduction may l imit the independent evolution of fruit and stamen production in A. biterna ta.