Detecting recent positive selection

in the genome

Wolfgang StephanAbt. Evolutionsbiologie

LMU München

Coalescent without recombination and selection

Past

Present

Sampled gene copies

T(2)

T(3)

T(4)

T(5)

Two-locus model of genetic hitchhiking

Selected locus Neutral locus

A

a

A

no recombination recombination

AA

a

Ancestral recombination graph with hitchhiking

T= 0 (Present)

T =

neutral phase

selective phase

neutral phase

Tlimit

Position (kb)

Heterozygosity

Expected hitchhiking effect of a beneficial mutation

Position (kb)

Heterozygosity

Composite-likelihood ratio test (Kim and Stephan 2002)

European Population

0.0000.0050.0100.0150.0200.0250.0300.0350.0400.0450.0500.055

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Recombination rate

Nu

cle

oti

de

div

ers

ity

African Population

0.0000.0050.0100.0150.0200.0250.0300.0350.0400.0450.0500.055

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Recombination rate

Nu

cle

oti

de

div

ers

ity

Demographic model of D. melanogaster

wapl

63 73 103 113

83 92

coding non-coding (intergenic)

EG:87B1.3 Pgd bcn92 wapl Cyp4d1 152A3.3152A3.7/Cyp4d14

Cyp4d2 / Cyp4ae1 /pn / Nmd3 / CG17776

17E2.1

non-coding (Intron (>300 bp))

Positions in kb

csw

23

13

Unc-76

03

EG:67A9.2EG:22E5.4/22E5.9

D:

(6 lines)

Europe

Africa