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Fish diversity
Laura (6)
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Species richness in vertebrates
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Genome and biodiversity
- Genome duplication and differential
rediploidisation
- Transposable elements
- Sex chromosomes and sex determination
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Sex determination systems in vertebrates
Ezaz et al. 2006
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Diversity of sex determination in fish

• Others
• - Autosomal influence
• - Polyfactorial
• - With several sex chromosomes
• With several pairs of sex chromosomes

Mank et al. 2006
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Diversity of sex determination in Poeciliids
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Sex determination systems in vertebrates master
sex-determining genes
SRY
dmrt1bY (Y)
medaka XY/XX
Ezaz et al. 2006
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Dmrt1bY, a recent master sex-determining gene
from the medaka fish Oryzias latipes
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Dmrt1bY, a recent master sex-determining gene
from the medaka fish Oryzias latipes
Tanaka et al. 2007
Dmrt1bY is not the universal master
sex-determining gene in fish
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Sex determination evolves very rapidly in
fish Possible association with the formation of
new sex-determining genes and new sex
chromosomes Possible role in speciation?
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Speciation genes on sex chromosomes
Qvarnström and Bailey 2009
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Sex determination evolution and prezygotic
reproductive isolation
X
Y
W
Z
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Fish models for the study of genetic sex
determination
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The genus Xiphophorus
www.Xiphophorus.org
Livebearing, freshwater fish, first described
1884 by Heckel, Genus contains three groups
Northern and Southern swordtails and
platyfish 23 species described
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Melanoma formation in Xiphophorus interspecific
hybrids
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Xiphophorus maculatus
Xiphophorus hellerii
X
-/- R-/R-
Xmrk/Xmrk
R/R
X
-/- R-/R-
Xmrk/-
R/R-
Xmrk/-
R/R-
Xmrk/-
R-/R-
- / -
R/R-
- /- R-/R-
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The sex-determining region of the platyfish X.
maculatus
Sex- determining locus
Melanoma- inducing oncogene
Macromelanophore determining locus
Red-yellow locus
Proto-oncogene
Tel
Cen
Y
Xmrk
Mdl
RY
Egfr-b
SD
X
Xmrk
SD
Mdl
RY
Egfr-b
SD
Egfr-b
W
P
Melanoma
P
puberty locus
WX WY XX
XY YY
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Positional cloning strategy
X
egfrbX
XmrkX
X-linked
Y
Y-linked
egfrbY
XmrkY
Bacterial artificial clones (BACs)
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Homomorphic sex chromosomes in the platyfish
XY
XX
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Neither dmrt nor sox genes in the
sex-determining region of the platyfish
No synteny with other fish sex chromosomes
Independent origin of sex-determining genes
and sex chromosomes in different fish species
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Comparative sexomics in vertebrates
Mammals Fish Origin ancient / unique recent /
multiple Master gene unique (Sry) multiple
(?) Differentiation yes restricted Degeneration ye
s (Y) restricted Suppres. recombination
yes yes Sex-specific gonad genes yes
(Y) yes Gene duplications yes yes Transposable
elements yes yes
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Since 2007 Equipe Génomique Evolutive des
Vertébrés Institut de Génomique Fonctionnelle de
Lyon CNRS/INRA/UCBL/ENSL Astrid Böhne Frédéric
Brunet Delphine Galiana-Arnoux Christina
Schultheis Amandine Darras Karim Madani Emilie
Deleva Laurie Nave Domittile Chalopin Vincent
Martin Jean-Nicolas Volff Until
2006 BioFuture Research Group Evolutionary Fish
Genomics Biozentrum, University of Würzburg,
Germany Christina Schultheis Qingchun
Zhou Cornelia Schmidt Agnès Dettai Anne-Marie
Veith Alexander Froschauer Yvonne Selz Marina
Vucic Sabine Matschl Jürgen Brandt Astrid Böhne
Wolfgang Bernhardt Marc Rathmann Reinhold
Hanel Ingo Braasch Jean-Nicolas Volff Mariam
Naciri
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Collaborations
Manfred Schartl (University of Würzburg,
Germany) Sylvie Samain, Jean Weissenbach
(Genoscope, Evry) Catherine Ozouf-Costaz, Agnés
Dettai (Muséum Natl dHistoire Naturelle,
Paris) Yann Guigen, Julien Bobe (INRA SCRIBE,
Rennes) Jean-Francois Baroiller, Helena DCotta
(CIRAD Montpellier) Indrajit Nanda, Michael
Schmid (University of Würzburg, Germany) Stefan
Chilmonczyk (INRA, Jouy en Josas,
France) Carsten Hoffman, Martin Lohse
(University of Würzburg, Germany) Christoph
Winkler (University of Singapore)
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