A role for a neo-sex chromosome in stickleback speciation.
Sexual antagonism, or conflict between the sexes, has been proposed as a driving force in both sex-chromosome turnover and speciation. Although closely related species often have different sex-chromosome systems, it is unknown whether sex-chromosome turnover contributes to the evolution of reproductive isolation between species. Here we show that a newly evolved sex chromosome contains genes that contribute to speciation in threespine stickleback fish (Gasterosteus aculeatus). We first identified a neo-sex chromosome system found only in one member of a sympatric species pair in Japan. We then performed genetic linkage mapping of male-specific traits important for reproductive isolation between the Japanese species pair. The neo-X chromosome contains loci for male courtship display traits that contribute to behavioural isolation, whereas the ancestral X chromosome contains loci for both behavioural isolation and hybrid male sterility. Our work not only provides strong evidence for a large X-effect on reproductive isolation in a vertebrate system, but also provides direct evidence that a young neo-X chromosome contributes to reproductive isolation between closely related species. Our data indicate that sex-chromosome turnover might have a greater role in speciation than was previously appreciated.
Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109, USA.
Jun
J
Kitano
Joseph A
JA
Ross
Seiichi
S
Mori
Manabu
M
Kume
Felicity C
FC
Jones
Yingguang F
YF
Chan
Devin M
DM
Absher
Jane
J
Grimwood
Jeremy
J
Schmutz
Richard M
RM
Myers
David M
DM
Kingsley
Catherine L
CL
Peichel
D000818:Animals; D049628:Body Size; D003433:Crosses, Genetic; D005260:Female; D049810:Genetic Speciation; D006824:Hybridization, Genetic; D007248:Infertility, Male / Q000235:genetics; D007564:Japan; D008297:Male; D052586:Mating Preference, Animal; D009792:Oceans and Seas; D010140:Pacific Ocean; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D012098:Reproduction / Q000235:genetics / Q000502:physiology; D012727:Sex Characteristics; D012730:Sex Chromosomes / Q000235:genetics*; D023701:Smegmamorpha / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics* / Q000502:physiology*; D012934:Social Isolation; D014998:Y Chromosome / Q000235:genetics