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SUMMARY:Natural variation in Antirrhinum and Arabidopsis - Dr Andrew Hudso
 n\, University of Edinburgh
DTSTART:20070308T160000Z
DTEND:20070308T170000Z
UID:TALK6022@talks.cam.ac.uk
CONTACT:3901
DESCRIPTION:Some of the most consistent morphological differences between 
 organisms at higher taxonomic levels involve differences in the size and s
 hape of organs. We have identified the genetic basis for such differences 
 between Arabidopsis ecotypes and between species of snapdragon (Antirrhinu
 m) that are adapted to very different habitats.  In Arabidopsis we find th
 at leaf and petal size differences are determined by a large number of gen
 es of relatively small effects and that each ecotype carries a combination
  of 'small' and 'large' genes\, suggestive of stabilising selection\, even
  in the flowers of this predominantly self-pollinating species.  Sampling 
 of Arabidopsis populations from Edinburgh suggests significant  migration\
 , outcrossing and local adaptation in the wild.\n\nIn contrast\, we find t
 hat organ shape and size differences between Antirrhinum species are deter
 mine by relatively few genes of more major effect\, that the genes affect 
 either cell division or cell expansion and that genes affecting organ size
  also affect shape - i.e. act allometrically. Some genes affect only leave
 s or floral organs while others act in both\, raising the possibility of s
 election having acted independently on flower size (e.g. in co-evolution w
 ith pollinators) and on leaf size (e.g. in response to water use efficienc
 y).\n\nTo interpret these findings in an evolutionary context\, we have at
 tempted to construct a phylogeny for the genus Antirrhinum.  Although we f
 ind strong support for ~20 distinct species\, we have so-far been unable t
 o resolve the relationships between them.  The results are consistent with
  rapid recent speciation\, possibly following hybridisation within glacial
  refugia. \n\nhttp://www.biology.ed.ac.uk/research/institutes/plant/pages/
 staff_pages/A_Hudson_staffpage.htm
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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