Download response to artificial selection for female and male floral

23806
Response to Artificial Selection for Female and Male Floral Biomass Allocation in
Gynodioecious Schiedea salicaria (Caryophyllaceae)
Tiffany Ng
Mentor: Ann Sakai & Stephen G. Weller
The plant genus Schiedea exhibits a wide range of breeding systems. Phylogenetic analysis suggests
that some species are undergoing evolution towards dioecy and show different stages of evolution. In
order for changes in these breeding systems to occur, allocation of resources for male and female
reproductive function must be heritable. Schiedea salicaria is a gynodioecious species with 13% females
in the population and previous studies show it is under strong selection for separate sexes. This
project studies the response of Schiedea salicaria to artificial selection to determine the genetic potential
to change reproductive resource allocation. We artificially selected two lines for high female function
(carpel and fruit biomass), two lines for high male function (stamen biomass), and had two control
lines, based on the family means of the traits. Tradeoffs between male and female function were
expected to occur, where the high female lines increased in carpel biomass and decreased in stamen
biomass, and the high male lines increased in stamen biomass and decreased in carpel biomass. In
high female lines, carpel and sepal/nectary biomass increased and stamen biomass did not change
relative to the controls. High male lines showed increased stamen biomass and no change in carpel
and sepal/nectary biomass. These results are consistent with the theory that this species has the
potential to evolve dioecy through changes in biomass allocation.