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SUMMARY:Evolutionary and demographic genetics of polymorphic sexual system
 s in plants - Spencer Barrett FRS\, University of Toronto
DTSTART:20160602T120000Z
DTEND:20160602T130000Z
UID:TALK65486@talks.cam.ac.uk
CONTACT:38889
DESCRIPTION:Plant populations of many species are reproductively subdivide
 d into morphologically distinct mating groups. These polymorphic sexual sy
 stems have been of considerable interest to evolutionary biologists since 
 Darwin’s classic work “Different Forms of Flowers on Plants of the Sam
 e Species” (1877). Indeed\, many fundamental concepts in genetics\, incl
 uding linkage\, supergenes\, epistasis and frequency-dependent selection w
 ere developed\, in part\, from early studies of plants with sexual polymor
 phisms. In this talk I will review our recent studies on two of the most a
 ttractive sexual polymorphisms for evolutionary analysis – dioecy and he
 terostyly – and address several outstanding issues concerned with their 
 evolution and maintenance. For dioecy\, I discuss the demographic and gene
 tic mechanisms governing biased sex ratios in sexually dimorphic populatio
 ns\, and recent insights into the evolution of sex chromosomes\, particula
 rly Y-chromosome degeneration and its potential as a mechanism causing fem
 ale-biased sex ratios in Rumex. For heterostyly\, I examine the ecological
  conditions favouring the evolutionary breakdown of this complex floral po
 lymorphism\, and the demographic and genomic consequences of the transitio
 n from outcrossing to selfing in Eichhornia. I also report on our recent e
 fforts to map the genetic architecture of tristyly and the selfing variant
 s causing transitions to autogamy. Throughout\, I stress the value of intr
 a-specific variation for studies in ecological genetics and evolutionary g
 enomics.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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