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SUMMARY:Genomics of speciation and adaptation in the Lake Malawi cichlid f
 ish radiation - Professor Richard Durbin\, Department of Genetics
DTSTART:20200213T140000Z
DTEND:20200213T150000Z
UID:TALK129511@talks.cam.ac.uk
CONTACT:Caroline Newnham
DESCRIPTION:Our genomes are both the product of evolution\, and the medium
  through which evolution acts.  Modern genomics allows us to observe direc
 tly the consequences of evolution acting on genetic variation\, to study t
 he processes that give rise to the diversity of life.  I will discuss our 
 studies on one of the largest recent adaptive radiations\, of over 500 spe
 cies of cichlid fish in Lake Malawi\, which have diverged within the last 
 million years.  These species demonstrate enormous variation in morphology
 \, diet\, behaviour and ecology\, although the mean genetic divergence bet
 ween species is just 0.2%\, only twice the diversity within modern humans.
   Over the last five years we have started to investigate the genetic hist
 ory and structure of the radiation by whole genome sequencing samples from
  over 300 species/populations.  There is not a simple tree-like phylogeny 
 but rather evidence of hybridisation at the base of the radiation and also
  at multiple points since.  In several cases this was associated with adap
 tive introgression of functional variation\, for example between deeply di
 verged deep water clades.  Sequences of over 600 samples from two recently
  diverging A. calliptera ecomorphs from the satellite crater lake Masoko r
 eveal 50-100 genomic “islands” of genetic divergence in a background o
 f very low population separation (4% Fst).  We have begun to use these dat
 a to map loci involved in specific traits by genome wide association.  Mos
 t strikingly\, we have identified two competing XY sex determination loci\
 , suggesting a possible role for rapid evolution of sex determination in s
 upporting adaptive speciation.
LOCATION:Part II Room\, Department of Genetics\, Downing Site
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