TY - JOUR
T1 - Restricted X chromosome introgression and support for Haldane's rule in hybridizing damselflies
AU - Swaegers, Janne
AU - Sanchez-Guillen, Rosa Ana
AU - Chauhan, Pallavi
AU - Wellenreuther, Maren
AU - Hansson, Bengt
PY - 2022/7/27
Y1 - 2022/7/27
N2 - Contemporary hybrid zones act as natural laboratories for the investigation of species boundaries and may shed light on the little understood roles of sex chromosomes in species divergence. Sex chromosomes are considered to function as a hotspot of genetic divergence between species; indicated by less genomic introgression compared to autosomes during hybridization. Moreover, they are thought to contribute to Haldane's rule, which states that hybrids of the heterogametic sex are more likely to be inviable or sterile. To test these hypotheses, we used contemporary hybrid zones of Ischnura elegans, a damselfly species that has been expanding its range into the northern and western regions of Spain, leading to chronic hybridization with its sister species Ischnura graellsii. We analysed genome-wide SNPs in the Spanish I. elegans and I. graellsii hybrid zone and found (i) that the X chromosome shows less genomic introgression compared to autosomes, and (ii) that males are underrepresented among admixed individuals, as predicted by Haldane's rule. This is the first study in Odonata that suggests a role of the X chromosome in reproductive isolation. Moreover, our data add to the few studies on species with X0 sex determination system and contradict the hypothesis that the absence of a Y chromosome causes exceptions to Haldane's rule.
AB - Contemporary hybrid zones act as natural laboratories for the investigation of species boundaries and may shed light on the little understood roles of sex chromosomes in species divergence. Sex chromosomes are considered to function as a hotspot of genetic divergence between species; indicated by less genomic introgression compared to autosomes during hybridization. Moreover, they are thought to contribute to Haldane's rule, which states that hybrids of the heterogametic sex are more likely to be inviable or sterile. To test these hypotheses, we used contemporary hybrid zones of Ischnura elegans, a damselfly species that has been expanding its range into the northern and western regions of Spain, leading to chronic hybridization with its sister species Ischnura graellsii. We analysed genome-wide SNPs in the Spanish I. elegans and I. graellsii hybrid zone and found (i) that the X chromosome shows less genomic introgression compared to autosomes, and (ii) that males are underrepresented among admixed individuals, as predicted by Haldane's rule. This is the first study in Odonata that suggests a role of the X chromosome in reproductive isolation. Moreover, our data add to the few studies on species with X0 sex determination system and contradict the hypothesis that the absence of a Y chromosome causes exceptions to Haldane's rule.
KW - Haldane's rule
KW - hybrid zone
KW - sex chromosome
KW - species divergence
U2 - 10.1098/rspb.2022.0968
DO - 10.1098/rspb.2022.0968
M3 - Article
C2 - 35855603
AN - SCOPUS:85134634937
SN - 0962-8452
VL - 289
JO - Proceedings of the Royal Society B: Biological Sciences
JF - Proceedings of the Royal Society B: Biological Sciences
IS - 1979
M1 - 20220968
ER -