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DTSTART:20171029T020000
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DTSTAMP:20260428T030316Z
UID:58ef76f689e76645841453@ist.ac.at
DTSTART:20170517T094500
DTEND:20170517T104500
DESCRIPTION:Speaker: Anja Marie Westram\nhosted by Nick Barton\nAbstract: O
 utlier scans facilitate the identification of loci potentially affected by
  divergent selection between ecotypes or incipient species. However\, thes
 e approaches have various shortcomings\; the strength and nature of select
 ion acting on outliers is often unclear\, and functional roles and locatio
 ns in the genome are commonly unknown. After performing outlier scans in o
 ur study organism\, the marine snail Littorina saxatilis\, we now use data
  from hybrid zones to fill some of these gaps. L. saxatilis contains two d
 istinct ecotypes\, adapted to wave-exposed vs. high-predation habitats and
  showing partial reproductive isolation. To gain insight into the genomic 
 basis of divergence\, we have phenotyped hundreds of snails sampled across
  a hybrid zone on the Swedish west coast and sequenced 40\,000 genomic mar
 kers. We have identified loci with steep allele frequency clines across th
 e habitat transition\, which often correspond to outliers from earlier wor
 k\, supporting the role of divergent selection. However\, we also show tha
 t clines for some loci do not coincide with the habitat transition and may
  reveal other axes of divergent selection. Using a genetic map\, we demons
 trate that divergent selection is pervasive across the genome. Currently w
 e are using an admixture mapping approach to establish the link between se
 lected loci and phenotypes.\nA particularly useful aspect of the L. saxati
 lis system is that divergent ecotypes have evolved repeatedly in multiple 
 geographical locations. A key question is to what extent the genetic basis
  of divergence – i.e. the set of loci under divergent selection – is the
  same across such instances of parallel divergence. Answering this questio
 n is hindered by the fact that local signatures of selection\, detected e.
 g. in outlier scans\, may be modified by genetic drift\, potentially leadi
 ng to an underestimation of the number of selected loci shared among locat
 ions. I will discuss potential future work that takes the effects of genet
 ic drift into account\, combining simulation approaches and analyses of L.
  saxatilis whole-genome resequencing data.
LOCATION:Mondi Seminar Room 3\, Central Building\, ISTA
ORGANIZER:abonvent@ist.ac.at
SUMMARY:Anja Marie Westram: Using hybrid zones to understand the links betw
 een genotype\, phenotype and selection
URL:https://talks-calendar.ista.ac.at/events/572
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