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SUMMARY:The evolution of meiosis and meiotic recombination in Arabidopsis 
 arenosa. - Dr Kirsten Bomblies\, John Innes Centre\, Norwich 
DTSTART:20171102T140000Z
DTEND:20171102T150000Z
UID:TALK75461@talks.cam.ac.uk
CONTACT:Caroline Newnham
DESCRIPTION:Meiosis is essential for fertility of sexual eukaryotes and it
 s core structures and progression are conserved across kingdoms. Neverthel
 ess\, meiotic proteins are often less conserved in primary sequence than w
 e might expect\, and sometimes show evidence of having experienced directi
 onal selection. Why? What challenges does meiosis face that might cause it
  to evolve adaptively and how does this alter the system? We study two imp
 ortant factors that can challenge the stability of meiosis and drive evolu
 tionary responses: whole genome duplication and temperature. My group seek
 s to understand how meiosis evolves in response to challenges\, that is\, 
 what its evolutionary potential is within the constraints of being an esse
 ntial and complex structural progression. We use Arabidopsis arenosa\, whi
 ch occurs naturally as an autotetraploid and a diploid\, and where both cy
 totypes have colonized a range of habitats. In a genome scan for adaptatio
 n to whole genome duplication\, we found that eight interacting meiotic pr
 oteins critical for axis formation and synapsis show strong evidence of ha
 ving been under selection in the tetraploid arenosas. This is associated w
 ith a reduction in crossover number\, and a greater tendency for terminal 
 localization of chiasmata. More recently\, we found that two of the same g
 enes under selection in tetraploids\, also show strong evidence of having 
 been under selection in a diploid A. arenosa lineage. This lineage coloniz
 ed a warmer lowland habitat (the ancestral form is found in cooler mountai
 n environments)\, we have evidence that this lineage evolved greater tempe
 rature tolerance of meiosis\, and also found that they\, too have fewer an
 d more distal crossovers in lab conditions. Distinct alleles of the same g
 enes were under selection after both whole genome duplication and habitat 
 colonization\, and thus have twice come under selection for apparently dis
 tinct reasons\; does this suggest evolutionary constraint on the system? D
 oes it indicate that the same processes are challenged by distinct stresse
 s? The finding that the genes that came under selection in both lineages a
 re known to interact also highlights the possible need for co-evolution of
  interacting partners in meiotic evolution\, which may be more broadly rel
 evant to the evolution of proteins that participate in large complexes.
LOCATION:Part II Room\, Department of Genetics\, Downing Site
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