Interspecific crossing and genetic mapping reveal intrinsic genomic incompatibility between two Senecio species that form a hybrid zone on Mount Etna, Sicily

Brennan, A.C.; Hiscock, S.J.; Abbott, R.J.

doi:10.1038/hdy.2014.14

Interspecific crossing and genetic mapping reveal intrinsic genomic incompatibility between two Senecio species that form a hybrid zone on Mount Etna, Sicily

Brennan, A.C.; Hiscock, S.J.; Abbott, R.J.

Authors

Dr Adrian Brennan a.c.brennan@durham.ac.uk
Associate Professor

S.J. Hiscock

R.J. Abbott

Abstract

Studies of hybridizing species can reveal much about the genetic basis and maintenance of species divergence in the face of gene flow. Here we report a genetic segregation and linkage analysis conducted on F2 progeny of a reciprocal cross between Senecio aethnensis and S. chrysanthemifolius that form a hybrid zone on Mount Etna, Sicily, aimed at determining the genetic basis of intrinsic hybrid barriers between them. Significant transmission ratio distortion (TRD) was detected at 34 (~27%) of 127 marker loci located in nine distinct clusters across seven of the ten linkage groups detected, indicating genomic incompatibility between the species. TRD at these loci could not be attributed entirely to post-zygotic selective loss of F2 individuals that failed to germinate or flower (16.7%). At four loci tests indicated that pre-zygotic events, such as meiotic drive in F1 parents or gametophytic selection, contributed to TRD. Additional tests revealed that cytonuclear incompatibility contributed to TRD at five loci, Bateson–Dobzhansky–Muller (BDM) incompatibilities involving epistatic interactions between loci contributed to TRD at four loci, and underdominance (heterozygote disadvantage) was a possible cause of TRD at one locus. Major chromosomal rearrangements were probably not a cause of interspecific incompatibility at the scale that could be examined with current map marker density. Intrinsic genomic incompatibility between S. aethnensis and S. chrysanthemifolius revealed by TRD across multiple genomic regions in early-generation hybrids is likely to impact the genetic structure of the natural hybrid zone on Mount Etna by limiting introgression and promoting divergence across the genome.

Citation

Brennan, A., Hiscock, S., & Abbott, R. (2014). Interspecific crossing and genetic mapping reveal intrinsic genomic incompatibility between two Senecio species that form a hybrid zone on Mount Etna, Sicily. Heredity, 113, 195-204. https://doi.org/10.1038/hdy.2014.14

Journal Article Type	Article
Acceptance Date	Jan 27, 2014
Online Publication Date	Mar 5, 2014
Publication Date	Sep 1, 2014
Deposit Date	Jun 12, 2014
Publicly Available Date	Jun 17, 2014
Journal	Heredity
Print ISSN	0018-067X
Electronic ISSN	1365-2540
Publisher	Springer Nature [academic journals on nature.com]
Peer Reviewed	Peer Reviewed
Volume	113
Pages	195-204
DOI	https://doi.org/10.1038/hdy.2014.14