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Abstract Detail



The evolutionary causes and consequences of dioecy across the land plants

Case, Andrea [1], Caruso, Christina [2].

Antagonistic cyto-nuclear interactions and the evolution of separate sexes in angiosperms.

Genes underlying sex determination in gynodioecious angiosperms represent a common example of both sexual antagonism and deleterious alleles favoring sexual system change in plants. Cytoplasmic male sterility (CMS) genes are sexually antagonistic because they eliminate male function (creating females) in favor of increased female fertility. Their presence selects for nuclear alleles (Rf) that restore male function and thus hermaphroditism in individuals. Whether this antagonism can maintain separate sexes within populations depends on the frequencies of CMS/Rf. In particular, Rf should spread to fixation and separate sexes should not be maintained unless carrying excess Rf alleles is deleterious (i.e. a cost of male-fertility restoration). Despite very clear expectations from theory that costs of restoration are necessary, there are still few empirical tests. Specifically, the role of cost of restoration has been difficult to document in natural populations of gynodioecious plants.
In this talk, we summarize some of our recent research on estimating costs of restoration in gynodioecious Lobelia siphilitica. We demonstrate that the cost of restoration varies among L. siphilitica populations. The cost of restoration is higher in populations with more females, as expected if cost is a key determinant of the frequency of Rf alleles and the persistence of separate sexes in species with CMS/Rf Our results suggest that interpreting CMS, Rf, and gynodioecy in light of sexual antagonism and deleterious alleles will be important for evaluating the generality of these phenomena in shaping the evolution of plant sexual systems.

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1 - Kent State University, Box 5190, 256 Cunningham Hall, Kent, OH, 44242-0001, USA, 330-346-0765
2 - University of Guelph, Department of Integrative Biology, New Science Complex, 50 Stone Road East, GUELPH, ON, N1G 2W1, Canada

Keywords:
sexual systems
gynodioecy
male sterility
cost of fertility restoration.

Presentation Type: Symposium or Colloquium Presentation
Session: SY05
Location: Jasperwood/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 2:45 PM
Number: SY05003
Abstract ID:402
Candidate for Awards:None


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