Genomic identification and characterization of the pseudoautosomal region in highly differentiated avian sex chromosomes.
The molecular characteristics of the pseudoautosomal region (PAR) of sex chromosomes remain elusive. Despite significant genome-sequencing efforts, the PAR of highly differentiated avian sex chromosomes remains to be identified. Here we use linkage analysis together with whole-genome re-sequencing to uncover the 630-kb PAR of an ecological model species, the collared flycatcher. The PAR contains 22 protein-coding genes and is GC rich. The genetic length is 64 cM in female meiosis, consistent with an obligate crossing-over event. Recombination is concentrated to a hotspot region, with an extreme rate of >700 cM/Mb in a 67-kb segment. We find no signatures of sexual antagonism and propose that sexual antagonism may have limited influence on PAR sequences when sex chromosomes are nearly fully differentiated and when a recombination hotspot region is located close to the PAR boundary. Our results demonstrate that a very small PAR suffices to ensure homologous recombination and proper segregation of sex chromosomes during meiosis.
Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
Linnéa
L
Smeds
Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
Takeshi
T
Kawakami
Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
Reto
R
Burri
Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
Paulina
P
Bolivar
1] Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden [2] Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
Arild
A
Husby
Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
Anna
A
Qvarnström
Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
Severin
S
Uebbing
Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
Hans
H
Ellegren
D000818:Animals; D005260:Female; D008040:Genetic Linkage; D016678:Genome / Q000235:genetics*; D008297:Male; D023421:Models, Animal; D046109:Passeriformes / Q000235:genetics*; D011995:Recombination, Genetic / Q000235:genetics; D012730:Sex Chromosomes / Q000235:genetics*