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Workshop on population and speciation genomics Walter Salzburger Zoological Institute University of Basel, Switzerland evolution “The process by which different kinds of living organism are believed to have developed from earlier forms during the history of the earth.” The Oxford Advanced Learner’s Dictionary evolution heritable variation selection + ADAPTATION INNOVATION SPECIATION species distribution map ‣ …are fundamental (real) natural units Bombina bombina Bombina variegata species frequency ‣ …are varied trait ? time species ‣ …are not (always) easy to define Two species appear to be present at one place, but those two “species” are connected by a series of forms that are geographically arranged in a ring. No phenetic character could be used, except arbitrarily, to divide the ring into two species. A division would be meaningless, as there really is a continuum, not a number of clear-cut, separate species. Stebbins (1994) Ring Species: species species ‣ “Species are groups of interbreeding natural populations that are reproductively isolated from other such groups” (Mayr 1963) Salzburger et al. (2002) P. ca Eu erul rop eus e The evolution of part of the original species into a new one renders the remaining populations paraphyletic. For example, the Blue Tit (Parus caeruleus) is a paraphyletic species. The North African subspecies P. c. degener and P. c. ultramarinus are the sister group to the European Blue Tit (P. c. caeruleus) plus the Eurasian Azul Tit (P. cyanus) with four subspecies (P. c. cyanus, flavipectus, tianshanicus, and yaniseensis). P. c Eu yanu ras s ia Paraphyletic Species: P. ca N- erul Af eus ric a ‣ …are not (always) easy to define speciation continuum species A no partial complete reproductive isolation ancestral species species B time speciation continuum divergence locus under selection species A chromosome [position] disruptive selection divergence hitchhiking genome hitchhiking post-speciation divergence reproductive isolation species B time ••• JL Feder, SP Egan & P Nosil (2012) TREE speciation continuum ! phenotypic difference RAD genome scans Misty Joes Roberts Boot ••• M Roesti, A Hendry, W Salzburger & D Berner (2012) Molecular Ecology ` ` ••• FC Jones et al. (2012) Nature Barrett et al. (2008) Science speciation continuum speciation continuum ••• V Soria-Carrasco et al. (2014) Science selection Charles R. Darwin (1809-1882) natural selection images: www.idscaro.net, www.wikipedia.com ‣ ... “is the process by which the forms of organisms in a population that are best adapted to the environment increase in frequency relative to less well-adapted forms over a number of generations” (Ridley 1996) sexual selection images: www.crbs.umd.edu, www.smh.com.au ‣ ...“is the selection on mating behavior, either through competition among members of one sex (usually males) for access to members of the other sex or through choice by members of one sex (usually females) for certain members of the other sex” (Ridley 1996) selection fitness competitors sexual selection individual fitness other members of the same sex natural selection fitness of the genotype other individuals in the same population selection reproduction heredity trait variation variation in fitness organisms must reproduce to form new generations offspring resemble parents (“like must produce like”) individuals in natural populations vary in (adaptive) traits individuals in natural populations vary in the number of their offspring that survive to reproduce (‘lifetime reproductive success’) (Ridley 2004; Stearns & Hoekstra 2005) ‣ ...operates if the following conditions are met: natural variation ‣ Natural populations show variation at all levels, from gross morphology to DNA sequences. Selection can only operate, if heritable variation exists. natural variation ‣ Natural populations show variation at all levels, from gross morphology to DNA sequences. Selection can only operate, if heritable variation exists. ‣ Natural variation is generated by two processes: recombination mutation “reshuffling” of genetic material by introducing or breaking up physical linkage generation of new genetic variation by “mistakes” during the copying of a DNA strand natural variation ‣ New mutations are only transmitted to the next generation, if they occur in germinal tissue! natural variation variation in: phenome morphology ecology behavior genome genome structure and/or ATG AAC GTA TGG AGG... Met Asn Val Trp Arg coding sequence and/or regulatory regions ATG AAC GCA TGG AGG... Met Asn Ala Trp Arg natural variation ` 100% astbur 50% 100% 1-90001 Astbur.: 50% 100% 1 Alignment neobri Neobri. (-) 1-89776 70%, 100 bp Criteria: 61 Regions: 2 Alignment orenil orenil. (+) 755 bp 13819-106 70%, 100 Criteria: 78 Regions: 3 Alignment psenye psenye (+) 32 bp 9404-1062 70%, 100 Criteria: 49 Regions: r bu X-axis: astn: 31 Resolutiosize: 100 bp Window gene n exo UTR CNS mRNA 12k 10k 8k 18k 16k 14k 50% 20k ••• The Heliconius Genome Consortium (2012) Nature C7orf57 100% 6k 4k 2k natural variation 0k 50% 100% 50% 100% 24k 22k 20k 34k 32k 30k 28k 26k 50% 40k 38k 36k 100% Fhl2 (2of2) 50% 100% C7orf57 50% 100% 40k 42k 44k 52k g element non-codin e divergenc 46k 48k 50k 54k 56k 58k 50% 60k miRNAs relaxed selection gene duplica tion transposable elements ••• D Brawand et al. (2014) Nature