Haldane's rule in the placenta: Sex‐biased misregulation of the Kcnq1 imprinting cluster in hybrid mice

Crosses between populations or species often display an asymmetry in the fitness of reciprocal F 1 hybrids. This pattern, referred to as isolation asymmetry or Darwin's Corollary to Haldane's Rule, has been observed in taxa from plants to vertebrates, yet we still know little about which factors determine its magnitude and direction. Here, we show that differences in offspring size predict the direction of isolation asymmetry observed in crosses between populations of a placental fish, Heterandria formosa . In crosses between populations with differences in offspring size, high rates of hybrid inviability occur only when the mother is from a population characterized by small offspring. Crosses between populations that display similarly sized offspring, whether large or small, do not result in high levels of hybrid inviability in either direction. We suggest this asymmetric pattern of reproductive isolation is due to a disruption of parent–offspring coadaptation that emerges from selection for differently sized offspring in different populations.

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Haldane's Rule

Encyclopedia of Genetics, Genomics, Proteomics and Informatics ◽

10.1007/978-1-4020-6754-9_7299 ◽

2008 ◽

pp. 836-837

Keyword(s):

Haldane’S Rule ◽

Haldane's Rule

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Genomic Conflicts Underlying Haldane's Rule

Genetics ◽

10.1093/genetics/133.2.425 ◽

1993 ◽

Vol 133 (2) ◽

pp. 425-432

Author(s):

A POMIANKOWSKI ◽

L D HURST

Keyword(s):

Haldane’S Rule ◽

Haldane's Rule

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Restricted X chromosome introgression and support for Haldane's rule in hybridizing damselflies

10.1101/2021.11.28.470238 ◽

2021 ◽

Author(s):

Janne Swaegers ◽

Rosa Ana Sanchez-Guillen ◽

Pallavi Chauhan ◽

Maren Wellenreuther ◽

Bengt Hansson

Keyword(s):

X Chromosome ◽

Sex Chromosomes ◽

Hybrid Zones ◽

Haldane’S Rule ◽

Haldane's Rule ◽

Genome Wide ◽

Determination System ◽

Heterogametic Sex ◽

Sex Determination System ◽

Genomic Introgression

Contemporary hybrid zones act as natural laboratories for the investigation of species boundaries and allow to 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 hybridisation. 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 adds to the few studies on species with X0 sex determination system and contradicts the hypothesis that the absence of a Y chromosome causes exceptions to Haldane's rule.

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