Evolutionary reasons for
sex linkage
• Sexual conflict
– Predicts initial X-linkage if genes that favor males but harm
females are recessive (Rice 1984)
– Predicts initial Z-linkage when SA genes are dominant
– Predict no bias once sex-limited
• Sexual selection: ornament-preference coevolution
– Predicts faster evolution of female preference genes when there
are X-linked or autosomal ornaments and X-linked preferences
(Kirkpatrick & Hall, 2004)
• Genomic conflict
– Predicts faster evolution of female preference genes for X-linked
indicators of X-chromosome meiotic drive (Lande & Wilkinson, 1999)
Why does mode of inheritance matter?
1. Sexual selection operates directly on males, indirectly on females.
Male heterogamety
Male
XY
Female
XX
Female heterogamety
Female
ZW
Male
ZZ
X-linked genes spend less time in males while Z-linked genes
spend more time in males, compared to autosomal genes.
Why does mode of inheritance matter?
2. Linkage disequilibrium between trait and preference depends on mode
X-linked
Male
XY
Autosomal
Female
XX
Male
XY
Female
XX
Linkage disequilibrium arises due to joint inheritance of ornament and
preference genes
Sexual selection and sex chromosomes
(Kirkpatrick & Hall, 2004)
better
*
Preference-display inheritance
*
*
better
Do sexually selected traits
exhibit sex-linkage?
• Are genes for sexually selected
traits sex-linked?
– YES – X
• Drosophila, mammals (Reinhold, 1998)
• human reproductive traits (Saifa & Chandra
1999; Lercher et al. 2003)
– YES – Z
• Butterflies (Prowell 1998; Iyengar 2002)
• Birds (Saether et al. 2007; Wright 2005)
• Are genes with male-biased
expression X-linked?
– NO - under-represented
• Drosophila soma (Parisi et al., 2003)
– YES - over-represented
• mosquitoes (Hahn & Lanzaro, 2005)
• mouse spermatogonia (Wang et al. 2001; Yang
2006)
Outline
• Stalk-eyed flies as a model for studying a sexually
selected trait
• What regions (QTL) influence eyestalk
expression?
• Which genes are expressed during eyestalk
development?
• Does sex linkage influence the rate of evolution of
eyestalk genes?
• Does sex linkage influence the expression of
eyestalk genes?
Eyestalks have evolved in 8
families of Acalyptrate flies
14 nuclear genes
full mtDNA genomes
Wiegmann et al. unpub.
Exaggerated eyestalks occur only in male flies
Richardia telescopica
Richardiidae (Peru)
Diopsosoma prima
Periscelididae (Brazil)
Teleopsis whitei
Diopsidae (Malaysia)
Achias rothschildi
Platystomatidae (New Guinea)
Eye-Stalk Sexual Dimorphism has evolved repeatedly in Diopsids
Teloglabrus entabenensis
Dimorphic
Equivocal
Dias. silvatica
Dias. obstans
Dias. fasciata
Eyespan
Monomorphic
Dias. dubia
Dias. sp.F
Dias. sp.W
Dias. albifacies
Dias. sp.Q
Dias. meigeni
Dias. conjuncta
Dias. nebulosa
Dias. aethiopica
Dias. elongata
Dias. longipedunculata
Dias. hirsutu
Teleo. breviscopium
Teleo. rubicunda
Teleo. quadriguttata
Cyrto. dalmanni
Cyrto. whitei
Cyrto. quinqueguttata
Eurydiopsis subnottata
Diopsis apicalis
Diopsis fumipennis
Most parsimonious
reconstruction of sexual
dimorphism in eyespan.
Diopsis gnu
Sphyr. munroi
Sphyr. brevicornis
Sphyr. detrahens
Sphyr. beccarri
Males
Females
Body length
Sexual dimorphism
Sexual dimorphism evolves due to change in
male eye span-body length allometry
Independent contrasts
Male slope
Female slope
Baker & Wilkinson 2001 Evolution
Teleopsis populations are genetically and
reproductively isolated
Belalong
100
100
100
100
Cameron/La
ngat
Bogor
T. dalmanni
Soraya
100
93
Bt Lawang
100
99
Gombak
100
100
100
NJ phylogram:
535 bp COII mtDNA
535 bp 16s mtDNA
655 bp wingless intron
T. whitei
Brastagi
86
Gombak
90
Chiang Mai
100
2.5 - 11 MYA
T. quinquegutatta
Swallow et al. 2005 Mol. Ecol.
0.005 substitutions/site
Bt Ringit
Male eyespan is under sexual selection
Males with longer eyespan roost
and mate with more females
(Wilkinson & Reillo 1994)
Male with longer relative eyespan
win contests (Panhuis et al. 1999)
Male with longer relative eyespan
are preferred by females (Wilkinson
et al. 1998; Hingle et al. 2001)
Eyespan is condition dependent,
but relative eyespan has a
genetic basis (Wilkinson & Taper 1999;
David et al. 2000)
Outline
• Why use stalk-eyed flies as a model for studying
sexually selection traits?
• Which genomic regions (QTL) influence eyestalk
expression?
• Which genes are expressed during eyestalk
development?
• Does sex linkage influence the rate of evolution of
eyestalk genes?
• Does sex linkage influence the expression of
eyestalk genes?
Selection on male eye span alters
brood sex ratios
Realized response
in eyespan
Wilkinson et al. 1998 Nature
X drive can catalyze sexual selection
• If a male ornament indicates absence of the
driving X chromosome
• then, choosy females, which avoid mating with SR
males, will produce more grandchildren as long as
there are more females than males in the
population
• This process leads to rapid evolution of an
autosomal female preference when genes for an
ornament are linked to X drive
• Occasional recombination (or imprecise female
choice) is necessary otherwise sexual selection
should eliminate drive
Lande and Wilkinson 1999 Genet Res
QTL mapping of eye span
Gen 45 intercross
XDYL-XXH
738 flies (2 families)
468 females
270 males
Gen 30 intercross
XYH-XXL
490 flies (1 family)
231 females
259 males
Number of males tested
Female-biased broods are due to X drive
Drive X fails to recombine
Chr 1
Chr 2
Chr X
Gen 30 F2 intercross
XY-XX
Chr XD
Gen 45 F2 intercross
XDY-XX
QTL for relative eye span
Johns et al. 2005 Proc. R. Soc. Lond. B
QTL for relative eye span
Johns et al. 2005 Proc. R. Soc. Lond. B
Eye span indicates drive X
Thus, females that choose long eye span mates produce more sons
XD
Only dimorphic Teleopsis populations carry SR
Sumatra
Pen Malaysia
C. dalmanni
Sumatra
Java
Thailand
10 changes
Wilkinson et al, 2003
= SR frequency
C. q.
Pen Malaysia
C. whitei
Pen Malaysia
Drive X evolves rapidly
Number of segregating sites in 3 Kb sequence
6
crc
18
71
Soraya
N = 13 males
395
autosomal gene
25
29
Gombak Non-drive
N = 14 males
21
2 X-linked regions
14
13
0
13
Gombak Drive
N = 11 males
3
1
2
70
167
125
106
Drive X evolves independently of
autosomal genes
3
1
2
70
167
125
106
2 X regions
21
395
6
crc
18
71
Note that drive X lacks
variation and is derived from
nondrive X chromosomes
2 autosomal regions
Drive X influences other traits
• Sperm length (drive sperm are shorter)
• Sperm storage organ size in females
• Sperm competition (drive sperm are less
competitive)
• Male fertility (drive males are less fertile)
• Mating rate (drive males mate less often)
• Female fecundity (heterozygous females
produce more offspring)
• Consistent with a chromosomal region rather
than a single pleiotropic gene
Outline
• Why use stalk-eyed flies as a model for studying
sexually selection?
• What genomic regions (QTL) influence eyestalk
expression?
• Which genes are expressed during eyestalk
development?
• Does sex linkage influence the rate of evolution of
eyestalk genes?
• Does sex linkage influence the expression of
eyestalk genes?
EST Sequencing and Analysis
• cDNA libraries were made from C. dalmanni eyeantennal imaginal discs at 3 stages:
– wandering larvae
– 1-3 d pupae
– 4-7 d pupae
Larval brain + eye disc
•
24192 cDNAs were bidirectionally sequenced and
annotated using the JGI EST pipeline and FlyBase
•
EST assembly summary
–
–
–
–
–
–
Total # of high quality ESTs
# of clusters in assembly
# clusters w/ significant (e-9) Blast hits
# of unique protein genes
# ORFs > 300 bp w/out Blast hit
Average unique sequence per gene
33,229
7,066
4,422
3,487
186
1.65 Kb
Eye-antennal
imaginal disc
EST representation in GO categories
essential to eye-stalk development
cell motility
metamorphosis
eye-antennal disc morphogenesis
regulation of cell shape
eye development
growth
axonogenesis
Wnt/N/smo/fz/TGFb/InR signaling pathways
actin cytoskeleton organization and biogenesis
morphogenesis of an epithelium
regulation of cell size
cell growth
regulation of body size
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
% of D.m. genes in EST database
0.8
0.9
GO categories that exhibit over-representation
with respect to developmental stage
0.9000
0.8000
0.7000
0.6000
0.5000
0.4000
0.3000
0.2000
0.1000
0.0000
Pre-pupal
Pupal 1-3
Pupal 4-6
Developmental Time
Cuticular protein 30B
Cuticular protein 30F
Cuticular protein 49Aa
Cuticular protein 49Ac
Cuticular protein 49Ae
Cuticular protein 56F
Cuticular protein 57A
Cuticular protein 62Bb
Cuticular protein 62Bc
Cuticular protein 64Ac
Cuticular protein 65Ec
Cuticular protein 66Ca
Cuticular protein 66Cb
Cuticular protein 66D
Cuticular protein 67Fa1
Cuticular protein 76Bd
Cuticular protein 92F
Cuticular protein 97Ea
Cuticular protein 97Eb
Cuticular protein 100A
Outline
• Why use stalk-eyed flies as a model for studying
sexually selection?
• What genomic regions (QTL) influence eyestalk
expression?
• Which genes are expressed during eyestalk
development?
• Does sex linkage influence the rate of evolution of
eyestalk genes?
• Does sex linkage influence the expression of
eyestalk genes?
Identifying sex-linked genes by CGH
• Designed custom 44K oligoarray
–
–
–
–
60 bp oligo probes
6-10 nonoverlapping probes/gene
3,400 genes from EST library
~200 ORFs
• Hybridize male and female
genomic DNA
– 4 replicates/sex/species
– 4 Teleopsis species
• Expect X-linked genes in females
to have 2-fold intensity of males
CGH chromosome inference:
T. dalmanni
Autosomal
Frequency
Y
-7.5
Median log2(F/M intensity)
X
CGH chromosome inference:
T. dalmanni
Y
Autosomal
X
PCR confirmation
Chr confirmation
Frequency
Chr Prediction
A
X
Y
A
27
0
0
X
0
7
0
Y
0
0
1
35/35 correct = 100%
-7.5
Median log2(F/M intensity)
Teleopsis has a neo-X = Dm 2L
Left neo-X
Moved onto neo-X
Muller elements in Drosophila
Y replacement
Note 1: Muller element A is the ancestral X
Note 2: X drive is common in obscura group flies, which have a fused X and also have a new Y
chromosome which contains genes not on XR (Carvalho et al 2009)
Schaeffer et al. 2008 Genetics
DrosophilaAnopheles
synteny
53% of X-linked genes in A.
gambiae are X-linked in D.
melanogaster
Drosophila-Anopheles
shared a common ancestor ~
260 MYA
Zdobnov et al. 2002 Science
T. dalmanni - D. melanogaster synteny
Gene movement ->
Td chromosome
Muller element A+D
C+E
B
CGH chromosome inference:
T. quinqueguttata
Autosomal
Frequency
Y
-5.0
Median log2(M/F intensity)
X
Recent gene movement
X
X
Median log2(CQ M/F intensity)
Autosome
Autosome
Cd chr
Cq
chr
A
X
Y
A
X
3105 17
12 560
2
0
2 = 2392
P < 0.0001
Median log2(CD M/F intensity)
Y
1
0
0
Gene movement to X is associated with
increased dimorphism in Teleopsis
Genes may leave X chromosome to avoid X chromosome inactivation
during meiosis
Sequence divergence using
relative branch lengths
To identify genes that evolve faster in stalk-eyed flies than in
Drosophila, we used relative branch lengths
All conseqs translated and aligned to
transcript/gene alignments for 3
Drosophila species and Anopheles.
Alignments for conseqs from same
gene were concatenated prior to BL
estimate. Trees constrained to ‘known’
topology generated with PhyML.
D. m.
CG10561:
D. p.
D. v.
C. d.
A. g.
scramb1:
D. v.
D. m.
D. p.
C. d.
A. g.
Distance measure: T.d. branch length / tree length
Teleopsis branch prop.
Transposed genes show faster divergence
Teleopsis chromosomal location
Sequence divergence by CGH
(Cd(m+f) - Cq(m+f))/(Cd(m+f) + Cq(m+f))
“Recent” gene divergence
To identify genes that have evolved rapidly between the dimorphic
and monomorphic stalk-eyed flies, we used the relative difference in
total signal intensity from the CGH microarray
R2 = 0.23, P < 0.0001
Dm-Cd divergence (1-BlastX)
CGH divergence and
ancestral X movement
CD-CQ divergence is highest
for Dm genes which move on
or off the X in Cd
source
F
P
Cd-Cq div
9.4
< 0.0001
Note: excludes unique Cd genes
(unknown location in Dm)
CGH divergence by
Dm chromosome arm
*
Divergence of eyespan genes
is greatest for genes which are
unique to C dalmanni
source
F
P
Dm arm
32.4
< 0.0001
Gene Duplication in EST Database
• Possible duplicates: 234 cases in which two or more clusters had
the top Blast hit to overlapping regions of the same D.m. gene
• Tentatively assigned clusters as paralogs
if >10% amino acid divergence for aligned
regions and all clusters are monophyletic
relative to D. mel and D. pseudo homologs
.67
.17
1.15
2.38
Cd Soraya crolA
1.21
1.57
.56
.34
.50
.31
.46
Cd B.Law crol
Cd Soraya crol
Cd Brunei crol
.55
.50
.27
1.01
Cd Bogor crol
Cd Langat crol
.38
zinc finger protein - 10 domains
Cw crol
dN/dS
.77
xxxxxxxxxxx
Cd Gombak crol
.16
confirmed by phylogenetic analysis of
~ 1700 bp of crol genes for 7
populations of C. dalmanni + C. whitei
Cd Gom crolA
Cd B.Law crolB
.40
• Example: crooked legs, 3 copies
Cd Gom crol
Cd Gombak crolA
1.18
• Found 20 gene duplicates. Overrepresented for genes involved in
spermatogenesis and mRNA binding
Cd B.Law crolA
.44
Cd Bras crol
Sex-linkage and gene duplication
• Gene duplications (21) preferentially involve neo-X
– 11 homologs on neo-X (Dm 2L) and 10 on ancestral A
 2 = 14.1, P = 0.0002
• Genes involved in duplications are more likely to
move chromosomes
– 10 genes in 21 sets moved chromosomes (exp 2.8%)
 2 = 31.0, P < 0.0001
• Duplicate copies preferentially move off neo-X
– 7 X -> A; 2 A -> X; 1 A -> Y
Sex-linkage and gene duplication evolution
Six autosome duplications:
Mean CGH divergence change = 0.15 ± 0.04
One autosome -> X duplication/translocation:
-> 2R
-> 2
-> 3R
-> X (Cd-Cq div: 0.48)
-> auto (Cd-Cq div: 0.79)
Outline
• Why use stalk-eyed flies as a model for studying
sexually selection?
• What genomic regions (QTL) influence eyestalk
expression?
• Which genes are expressed during eyestalk
development?
• Does sex linkage influence the rate of evolution of
eyestalk genes?
• Does sex linkage influence the expression of
eyestalk genes?
Sex-bias by species gene expression
• Comparison
– Male vs female T. dalmanni and T. quinqueguttata
– Using probes with least divergence in CGH
• Method
– Sample: eye-antennal imaginal discs from 25
wandering larvae
– Sex: genotyped larvae using X & Y-linked
microsat markers, then pooled discs by sex
– Replicates: 8 samples/sex/spp with dye swap
– Hybridized to 44k custom oligoarrays
•
•
•
•
5 nonoverlapping probes/gene
each probe printed in duplicate
3320 unique genes
Used normalized (intensity – background) intensity
– Averaged log2(M/F intensity) over probes/gene
&
Sex-bias x species gene expression
SAM ANOVA
569/1922 genes
FDR < 0.1%
Average log2(M/F) expression
Sex-biased expression, sexual
dimorphism and sex linkage
Average log2(M/F) expression
Sex-biased expression, sexual
dimorphism and gene movement
Sex-biased gene expression and
gene movement among Teleopsis
Gene name
capulet
RNA polymerase II 215kD subunit
ORF-65
extradenticle
aubergine
Deoxyribonuclease II
ORF-25
Spindly
CG9246
La autoantigen-like
Ran GTPase activating protein
mitochondrial ribosomal protein L28
Pendulin
msb1l
CG3305
CG14341
CG7870
Dm Td
2L A
X
A
X
X
X
2L X
3R X
X
2L X
2L X
2L X
2L X
2L X
2L X
2L X
2L X
2L X
2L X
Tq
X
Y
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
Conclusions
• Exaggerated eyestalks are influenced by X-linked genes
– X chromosome drive likely has influenced sexual selection and
may have facilitated evolutionary change due to restricted
recombination.
• X chromosome history influences divergence rates
– Gene movement on or off the X results in faster divergence.
– Unique stalk-eyed fly genes evolve faster between sexually
monomorphic and dimorphic species
– Gene duplications preferentially involve neo-X
• X linkage and history influence gene expression
– Sexual dimorphism is associated with female bias among X-linked
genes
– Genes that moved off the X show male-biased expression while
those that joined the X show female-biased expression in the
dimorphic species, consistent with sexual conflict
Acknowledgements
Collaborator:
Rick Baker
(AMNH)
Postdocs:
Philip Johns
(Bard College)
Xianhui Wang
Leanna Birge
(UCL)
Technicians:
Marie Pitts
Sarah Josway
Graduate students:
Sarah Christianson
Jackie Metheny
Undergraduates:
Cara Brand
and many others!
Gene expression between lines
• Comparison
– High vs low lines after 50 generations
of selection on relative eye span
• Method:
– Sample: eye-antennal imaginal discs
from 25 wandering larvae
– Replicates: 8 samples per line, with
dye swap
– Hybridized to 44k custom oligoarrays
• three nonoverlapping oligos/gene
• each oligo printed in triplicate
• 3320 unique genes
– Average log2(H/L intensity) over
probes/gene
Biased gene expression between lines
SAM (FDR = < 1%)
176 biased clusters; 111 genes
19 sig genes unique to Cd
Gene expression and ancestral
X transposition
source
Cd-Dm chr
F
P
1.6
0.19
N = 2969; excludes Cd genes
with unknown location in Dm
Gene expression and recent sex
chromosome transposition
source
Cq-Cd chr
F
P
1.06
0.38
N = 3053; includes Cd genes
with unknown location in Dm
Gene expression by chromosome arm
Biased expression is
greatest for
*
•
154 Cd genes which are
not detected in Dm
•
No effect of Cd X
chromosome
source
F
P
Dm arm
9.0
< 0.0001
Cd chr
1.0
0.322
Where do drive chromosomes
come from?
Hypothesis: drive chromosomes arise
when new sex chromosomes evolve
because suppressors are initially
absent
Biased sex ratios in medflies
caused by B chromosomes
Y+B
Percent males
X+B
Basso et al. 2009 PLoS One
Where do drive chromosomes
come from?
Hypothesis: drive chromosomes arise
when new sex chromosomes appear,
which in flies may be initiated by
fusions of B chromosomes or other
elements
Candidate genes for expression regulation
Single amino-acid repeat polymorphisms (SARPs)
– Common in coding sequences of transcription factors
– Repeat expansions/contractions occur more often than point mutations
– Can enhance or suppress transcription in a length dependent manner
Fondon & Gardner 2004
Single amino-acid repeats in
C. dalmanni EST database
0.6
Q repeat genes are most common
Transcription factors are over-represented
Gene divergence is less than for other genes
Proportion
0.5
0.4
AA repeat > 8 bp (N = 129)
0.3
AA abundance (N = 1651205)
0.2
0.1
0
Q
L
F
N
S
T
A C
D
E G
I
Y
P
Amino acid code
K
V
R
H
M W
For homologous genes, Q repeats
are longer in Cd than Dm
Chromosome
location does not
influence repeat
length or purity
Q rep
all genes
No. Cd - Dm Q repeats per gene
X
A
9
54
542 2894
Q repeats vary in length
between populations
No Q repeats for D. melanogaster homologue in 4 of 63 genes, e.g.
crc (cryptocephal): Ecdysone-regulated transcription factor
Cd_CRC-A: 6
VLTQLTPPHSPPQTAASSAFPNASIETSTNVNDAPF-QVSSTPPLASPVQI--------- 55
Dm_CRC-A: 148 ILQQLTPPQSPPQ------F------------DA-YKQAGDAQP--KPVLVKAEQKVQCY 186
Cd_CRC-A: 56 ---VTNDKFGSSAVQPTFLNFNNWQQQQQQQQQQQQEQQQQQNQHSTVGALNNEFNVDIA 112
Dm_CRC-A: 187 TPDVTH---AASAT-P-F-NFTNW-----------------------VGG--SE----IA 211
Cd_CRC-A: 113 REMQIVDEIVNKRVKEL-FDSN----NDDCESMSSYSAPSQIES-ST-----------DE 155
Dm_CRC-A: 212 RENQLVDDIVNMRAKELELSTNWQQLNEDCESQAS----SSLDSRSTGSGVCSSIADADE 267
Cd_CRC-A: 156 EWMP---CSSYSSAGSSPVHNGCEESSLKATATNGS--KKRTRPYGRGIEDRKLRKKEQN 210
Dm_CRC-A: 268 DWVPELISSS-----SSPAPTTIEQSA--------SQPKKRTRTYGRGVEDRKIRKKEQN 314
Cd_CRC-A: 211 KNAATRYRQKKKLEMENVLSEEQQLTQRNDELKRILSDR 249
Dm_CRC-A: 315 KNAATRYRQKKKLEMENVLGEEHVLSKENEQLRRTLQER 353
X-linked Q repeat genes tend to
be more polymorphic
F = 4.31
P = 0.051
Q repeat gene association study
Sires
Dams
Offspring
(n = 300)
(n = 300)
(n = 2000)
Breeding
values/family
A. Screen variable loci (n=32)
20
1.
X
2.
275.
.
.
298.
=
20
20
X
X
=
20
20
=
20
20
X
=
20
20
X
=
20
20
299.
300.
Progeny
breeding
values
20
20
X
3.
.
.
.
25.
=
X
X
=
20
=
20
20
HQQQQQQQQQQL
............
............
............
............
............
............
............
............
............
............
(n = 50 fams)
Parental
Genotypes
HQQQQ---QQQQQQL
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
A. Autosomal loci screen
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Female LS-ES
Locus
Bar1
Bif ocal
CG4409
CG10082
CG10321
CG10435
CG11848
CG12104
CG31064
CG31224
CG32133
CG33692
CG34347
Cap-n-coll ar
Corto
Domi no
E5
Ecdysone-induced protein 75B
Grainy head
M-spondin
Mastermi nd
SRPK
Tenascin major
Toutatis
Trachealess
F
0.45
1.46
1.43
1.57
0.8
0.04
6.01
3.19
0.35
1.11
1.25
2.98
0.66
0.55
2.25
1.58
0.85
2.71
1.09
0.37
1.52
1.95
0.56
1.07
0.82
P
0.77
0.20
0.24
0.18
0.49
0.85
0.0002
0.046
0.93
0.37
0.28
0.011
0.78
0.58
0.022
0.11
0.43
0.07
0.38
0.83
0.21
0.06
0.57
0.40
0.44
Male LS-ES
F
0.62
1.89
1.38
1.77
1.82
0.04
4.72
2.09
0.69
1.76
2.84
3.16
1.01
0.57
2.59
2.04
0.90
6.13
1.38
0.75
2.19
2.54
1.91
1.23
3.00
P
0.65
0.09
0.26
0.13
0.13
0.84
0.0016
0.13
0.68
0.10
0.0079
0.0074
0.45
0.57
0.0087
0.029
0.41
0.0032
0.22
0.56
0.08
0.015
0.15
0.28
0.055
N
92
91
92
88
88
89
98
89
98
73
88
98
89
89
96
85
84
91
86
87
88
99
90
89
92
A. X-linked loci screen
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Female LS-ES
Male LS-ES
Locus
Parent
F
P
F
P
N
Bunched
Male
Female
0.22
0.71
0.80
0.62
0.42
0.88
0.66
0.50
45
45
CG8668
Male
Female
0.65
0.64
0.69
0.77
0.60
1.18
0.73
0.34
48
46
CG10107
Male
Female
4.18
0.99
0.011
0.46
3.03
0.97
0.039
0.47
48
49
CG31738
Male
Female
2.04
0.81
0.12
0.55
1.87
1.83
0.15
0.13
49
50
Cryptocephal
Male
Female
0.82
0.33
0.54
0.92
1.28
0.71
0.29
0.65
50
49
Q repeat gene association study
Sires
Dams
Offspring
(n = 300)
(n = 300)
(n = 2000)
A. Screen variable loci (n=32)
20
1.
X
2.
Progeny
breeding
values
20
20
X
3.
.
.
.
25.
=
=
20
20
X
X
=
20
20
=
20
HQQQQQQQQQQL
............
............
............
............
............
............
............
............
............
............
(n = 50 fams)
Parental
Genotypes
HQQQQ---QQQQQQL
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
B. Confirm associations
275.
.
.
298.
20
X
=
20
Progeny
phenotypes
20
X
=
20
(n > 300)
20
299.
300.
X
X
=
20
=
20
20
HQQQQQQQQQQL
............
............
............
............
............
............
............
............
............
............
Progeny
Genotypes
HQQQQ---QQQQQQL
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
.....QQQ.......
B. Progeny genotype-phenotype associations
Females
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Source of variation
CG33692 (1)
Family
Genotype
Error
df
5
7
168
Var Comp%
Males
F
P
df
Var Comp%
F
P
37.3
5.6
13.2
2.7
< 0.0001
0.011
5
7
200
38.6
6.8
18.2
3.5
< 0.0001
0.0013
Ecdysone-induced protein 75b (1)
Family
4
Genotype
2
Error
134
32.9
5.4
14.3
4.6
< 0.0001
0.012
4
2
119
43.3
1.2
19.2
1.8
< 0.0001
0.18
CG11848 (2)
Family
Genotype
Error
5
4
177
36.9
2.0
14.5
1.7
< 0.0001
0.16
5
4
202
53.6
1.1
31.7
1.6
< 0.0001
0.17
Corto (2)
Family
Genotype
Error
5
9
175
33.7
4.9
10.5
2.1
< 0.0001
0.035
5
9
200
46.1
1.1
18.4
1.3
< 0.00 01
0.23
CG10107 (X)
Family
Genotype
Error
4
5
143
47.7
-1.0
16.2
0.7
< 0.0001
0.59
4
5
144
50.6
6.5
22.6
4.5
< 0.0001
0.0049
Genotype-phenotype associations
A. Progeny breeding values by parent genotypes
CG33692 Dm X -> Cd A
B. Progeny phenotypes by progeny genotypes
CG10107 Dm A -> Cd X
Cq A -> Cd X
Multiple SR haplotypes occur in a population
Microsatellite haplotype
(ms125, 244, 395 bps)
Screen of 89 Gombak males at 3 X-linked microsatellite loci
Wilkinson et al, 2006
If there is an arms race between
a drive X and suppressors in
each population, then matings
between populations should
reveal cryptic drive
Reproductive isolation increases
with genetic distance
(reciprocal matings among 8 populations)
Matings/h
Progeny/2 wks
Each data point represents average values from 16 cages containing 1 male and 3 females
Christianson et al. (2005) Evolution
Cross-population matings produce sterile
male, fertile female progeny
Proportion hybrids fertile
(Haldane’s Rule)
Gombak (Malaysia) x Soraya (Sumatra)
between parental populations
Christianson & Wilkinson 2005 Evol
Mapping cryptic drive
GBX
(n = 438)
SBX
(n = 261)
Determine brood sex ratios for all fertile BX progeny
Genotype all progeny at 30 microsatellite loci
Intact X is required for fertility
3
1
2
70
167
125
106
3
1
2
GBX
# S Fertile Sterile
alleles
21
0
159
70
167
125
106
# G Fertile Sterile
alleles
21
123
395
SBX
0
121
108
>1
0
21
395
6
6
crc
18
>1
6
152
crc
18
71
71
SBX reveals female-biasing modifiers
Chr 1
GSRX chromosome is lost
presumably because it
causes hybrid inviability.
One region on chr 1 is
associated with femalebias
**
**
Proportion male progeny
GBX reveals male biasing modifiers
Chr 1
Chr 2
*
***
*
**
GSRX chromosome is
present, but unrelated to
male-biased sex ratios
**
Parts of chr 1 and 2 are
associated with male-bias
***
***
***
Proportion male progeny