Evolutionary trees and population genetics: a family reunion 9 October 2009.
Joe Felsenstein
500th anniversary (or something) of the University of Chicago
Evolutionary trees and population genetics: a family reunion – p.1/44 The modern synthesis, part 1
R. A. Fisher J. B. S. Haldane Sewall Wright
Evolutionary trees and population genetics: a family reunion – p.2/44 The modern synthesis, part 2
Ernst Mayr George Gaylord Simpson Sir Julian Huxley
G. Ledyard Stebbins Theodosius Dobzhansky
Evolutionary trees and population genetics: a family reunion – p.3/44 Population genetics, around 1970
δφ δ 2 __ __ 1 ___δ = − M(x) φ(x) + __ V(x) φ( x) δτ δ x ( ) 2 2 () δ x
the species boundary
Evolutionary trees and population genetics: a family reunion – p.4/44 Population genetics, around 1970
δφ δ 2 __ __ 1 ___δ = − M(x) φ(x) + __ V(x) φ( x) δτ δ x ( ) 2 2 () δ x
the species boundary
Heare bee monsteres
Evolutionary trees and population genetics: a family reunion – p.5/44 Finding molecular variation
Richard Lewontin and Jack Hubby’s 1966 paper on protein variation (using gel electrophoresis) found many loci to show variation at the molecular level. It was not obvious that this variation affected fitness. Lewontin pointed out that this “neutral mutation” might account for much of the molecular variation within populations.
Evolutionary trees and population genetics: a family reunion – p.6/44 The neutral mutation theory
Moto¯ Kimura with his family in Mishima, Japan in the 1960s. The greatest theoretical population geneticist of the late 1900s, he was the chief advocate for the neutral mutation theory and worked out many of its consequences.
Evolutionary trees and population genetics: a family reunion – p.7/44 Lots of variation at the DNA level
Marty Kreitman, as a student of Lewontin’s in the early 1980s, used early sequencing methods to look for variation in DNA sequences. Result: you are heterozygous about every 1500 nucleotides.
Evolutionary trees and population genetics: a family reunion – p.8/44 A typical locus showing SNP variation
(From Debbie Nickerson’s SeattleSNPs project). Single-nucleotide polymorphisms (SNPs) at the Matrix Metalloproteinase 3 locus.
Evolutionary trees and population genetics: a family reunion – p.9/44 Molecular evolution (1963 on)
Linus Pauling in 1963 Emile Zuckerkandl, more recently
Evolutionary trees and population genetics: a family reunion – p.10/44 Molecular evolution and phylogeny methods
Population genetics Cavalli−Sforza Fitch Edwards, me Dayhoff (Sankoff) Sokal Biochemistry Numerical Molecular (and molecular phylogenies evolution Wilson biology) Goodman (Sneath) Systematics Farris
People who pioneered in phylogeny methods and the analysis of molecular evolution data with them.
Evolutionary trees and population genetics: a family reunion – p.11/44 An example: who is most closely related to whales?
from Amrine-Madsen, H. et al., 2003, Molecular Phylogenetics and Evolution
Evolutionary trees and population genetics: a family reunion – p.12/44 Molecular phylogenies Some examples of other important conclusions from molecular phylogenies:
Using immunological distances, Morris Goodman (1962 on) and later Wilson and Sarich (1966) show that humans, gorilla, and chimps were a clade. Wilson and Sarich (in that work, 1967) date the divergence of humans to 5 million years. Charles Sibley and Jon Ahlquist (1984) use DNA hybridization to argue for the clade humans-chimps. Carl Woese (1978) uses rRNA trees to introduce evolution into microbiology, argue for the domain Archaea. Much progress on early radiation of angiosperms Protostome-deuterostome tree of metazoans (more or less) replaced by deuterostome-lophotrichozoa-ecdysozoa tree. Fungi closer to animals than either is to plants. Symbiotic origin of mitochondria and of chloroplasts verified. Amphioxus diverged before split of tunicates from craniate chordates. Lots of horizontal gene transfer in prokaryotes, almost not a tree.
Evolutionary trees and population genetics: a family reunion – p.13/44 Wen-Hsiung Li
Evolutionary trees and population genetics: a family reunion – p.14/44 Wen-Hsiung Li’s work on gene duplication
C5-cytosine methyltransferase gene family tree. Where are humans? (from Ponger and Li, 2005, Molecular Biology and Evolution) Evolutionary trees and population genetics: a family reunion – p.15/44 The “mitochondrial Eve” study in 1987
Rebecca Cann, Mark Stoneking, and the late Allan Wilson. In 1987 they made a molecular tree of mitochondria from humans.
Evolutionary trees and population genetics: a family reunion – p.16/44 One female ancestor? of what? When? Where?
Evolutionary trees and population genetics: a family reunion – p.17/44 My ancestor?
Charles the Great born 747 (Charlemagne)
about 44 more generations
1850s Cornelia John Maud William Itzhak Jacob 1880s Helen Will Sheimdel Lev 1910s Eleanor Jake 1942 Joe
Evolutionary trees and population genetics: a family reunion – p.18/44 Chromosome 1, back up one lineage
−6 (none) −5 −4 −3 −2 −1 now
Evolutionary trees and population genetics: a family reunion – p.19/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.20/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.21/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.22/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.23/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.24/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.25/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.26/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.27/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.28/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.29/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.30/44 Coalescent genealogy for one gene
Time
Evolutionary trees and population genetics: a family reunion – p.31/44 Untangling the crossed lines ...
Time
Evolutionary trees and population genetics: a family reunion – p.32/44 Genealogy of a sample of 3 copies
Time
Evolutionary trees and population genetics: a family reunion – p.33/44 J. F. C. Kingman’s (1982) “coalescent” 1. start with n tips 2. go back an amount of time drawn from Exponential 4N n(n−1) 3. join a random pair of the n 4. n ← n − 1 5. if n =1 stop, else go to step 2.
This excellently approximates the distribution of genealogies which arise from samples from a standard (Wright-Fisher) population genetics model with a population size of N, provided n2 ≪ N
Evolutionary trees and population genetics: a family reunion – p.34/44 Pioneer of coalescent theory
Dick Hudson, pioneered understanding of coalescents having recombination or natural selection
Evolutionary trees and population genetics: a family reunion – p.35/44 A coalescent with recombination
Recomb.
Different markers have slightly different coalescent trees
Evolutionary trees and population genetics: a family reunion – p.36/44 Coalescents for two loosely-linked genes
locus A locus B = recombination both
Evolutionary trees and population genetics: a family reunion – p.37/44 Species trees and trees of gene copies
N N 1 2
t 1
N 3 N 4
t 2
N 5
Evolutionary trees and population genetics: a family reunion – p.38/44 Species trees and trees of gene copies
N N 1 2
t 1
N 3 N 4
t 2
N 5
Evolutionary trees and population genetics: a family reunion – p.39/44 Species trees and trees of gene copies
N N 1 2
t 1
N 3 N 4
t 2
N 5
Evolutionary trees and population genetics: a family reunion – p.40/44 Protists and bacteria – a worry
If protist (or bacterial) populations remain large for long periods of time ...
8 10 generations
population size 10 10
... is it possible that some apparent horizontal gene transfer events are actually just species-tree / gene-tree discrepancies due to coalescent effects? Has this been examined?
Evolutionary trees and population genetics: a family reunion – p.41/44 Approaches to breaching the species barrier
Jerry Coyne Allen Orr
Direct assault. Make use of cases where we can cross species or incipient species. Jerry Coyne, Allen Orr, Nick Barton, etc.
Evolutionary trees and population genetics: a family reunion – p.42/44 Approaches to breaching the species barrier
Jerry Coyne Allen Orr
Direct assault. Make use of cases where we can cross species or incipient species. Jerry Coyne, Allen Orr, Nick Barton, etc.
QTLs across species. e.g., Toby Bradshaw and Doug Schemske
Evolutionary trees and population genetics: a family reunion – p.42/44 Approaches to breaching the species barrier
Jerry Coyne Allen Orr
Direct assault. Make use of cases where we can cross species or incipient species. Jerry Coyne, Allen Orr, Nick Barton, etc.
QTLs across species. e.g., Toby Bradshaw and Doug Schemske
Going round the other way. Used inadvertently by people studying molecular evolution, then coalescents.
Evolutionary trees and population genetics: a family reunion – p.42/44 Approaches to breaching the species barrier
Jerry Coyne Allen Orr
Direct assault. Make use of cases where we can cross species or incipient species. Jerry Coyne, Allen Orr, Nick Barton, etc.
QTLs across species. e.g., Toby Bradshaw and Doug Schemske
Going round the other way. Used inadvertently by people studying molecular evolution, then coalescents.
Study of coalescents at time of speciation. Jody Hey, Rich Kliman.
Evolutionary trees and population genetics: a family reunion – p.42/44 Approaches to breaching the species barrier
Jerry Coyne Allen Orr
Direct assault. Make use of cases where we can cross species or incipient species. Jerry Coyne, Allen Orr, Nick Barton, etc.
QTLs across species. e.g., Toby Bradshaw and Doug Schemske
Going round the other way. Used inadvertently by people studying molecular evolution, then coalescents.
Study of coalescents at time of speciation. Jody Hey, Rich Kliman.
Synonymous/nonsynonymous comparisons. Masatoshi Nei, Takashi Gojobori, Ziheng Yang, Rasmus Nielsen, John Huelsenbeck Evolutionary trees and population genetics: a family reunion – p.42/44 Between-species and within-species evolutionary work
They are increasingly coming into contact.
Evolutionary trees and population genetics: a family reunion – p.43/44 Between-species and within-species evolutionary work
They are increasingly coming into contact.
Signs of this as well in a new wave of work on modelling quantitative genetics in natural populations
Evolutionary trees and population genetics: a family reunion – p.43/44 Between-species and within-species evolutionary work
They are increasingly coming into contact.
Signs of this as well in a new wave of work on modelling quantitative genetics in natural populations
Renewed controversy about models of speciation (Doebeli versus Gavrilets)
Evolutionary trees and population genetics: a family reunion – p.43/44 Between-species and within-species evolutionary work
They are increasingly coming into contact.
Signs of this as well in a new wave of work on modelling quantitative genetics in natural populations
Renewed controversy about models of speciation (Doebeli versus Gavrilets)
But ... what do we call the event?
Evolutionary trees and population genetics: a family reunion – p.43/44 Between-species and within-species evolutionary work
They are increasingly coming into contact.
Signs of this as well in a new wave of work on modelling quantitative genetics in natural populations
Renewed controversy about models of speciation (Doebeli versus Gavrilets)
But ... what do we call the event? The Reunion?
Evolutionary trees and population genetics: a family reunion – p.43/44 Between-species and within-species evolutionary work
They are increasingly coming into contact.
Signs of this as well in a new wave of work on modelling quantitative genetics in natural populations
Renewed controversy about models of speciation (Doebeli versus Gavrilets)
But ... what do we call the event? The Reunion? The Final Roundup?
Evolutionary trees and population genetics: a family reunion – p.43/44 Between-species and within-species evolutionary work
They are increasingly coming into contact.
Signs of this as well in a new wave of work on modelling quantitative genetics in natural populations
Renewed controversy about models of speciation (Doebeli versus Gavrilets)
But ... what do we call the event? The Reunion? The Final Roundup? (not The Postneodarwinian Synthesis)
Evolutionary trees and population genetics: a family reunion – p.43/44 Between-species and within-species evolutionary work
They are increasingly coming into contact.
Signs of this as well in a new wave of work on modelling quantitative genetics in natural populations
Renewed controversy about models of speciation (Doebeli versus Gavrilets)
But ... what do we call the event? The Reunion? The Final Roundup? (not The Postneodarwinian Synthesis) (definitely not The Postmodern Synthesis)
Evolutionary trees and population genetics: a family reunion – p.43/44 Thousands of SNPs?
SNPs will help integrate the statistical variation within populations, between populations, and between species.
They will also allow us to connect QTL statistical genetics with morphological phylogenies
Still, there will be a lot of statistics to do to correct for false positives.
Evolutionary trees and population genetics: a family reunion – p.44/44