Assortative Mating in Hybrid Zones Is Remarkably Ineffective in Promoting Speciation

Irwin, Darren E.

doi:10.1086/708529

Cited by 89 publications

(125 citation statements)

References 91 publications

(93 reference statements)

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“…Collectively, the published data suggest that male hybrids have a significant loss in reproductive fitness compared to both Golden‐winged and Blue‐winged Warblers. Although our estimate of behavioral isolation is much higher than our estimate of sexual selection against hybrids (Figure 2), recent work suggests that even weak postzygotic reproductive isolating barriers can potentially play a larger role in reducing gene flow than strong prezygotic barriers (Irwin, 2020). Thus, the reduced mating success of hybrids may be just as, if not more, important to speciation in this system as behavioral isolation.…”

Section: Discussioncontrasting

confidence: 75%

Implications for evolutionary trends from the pairing frequencies among golden‐winged and blue‐winged warblers and their hybrids

Confer

Porter

Aldinger

et al. 2020

Ecology and Evolution

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Section: Discussioncontrasting

confidence: 75%

Implications for evolutionary trends from the pairing frequencies among golden‐winged and blue‐winged warblers and their hybrids

Confer

Porter

Aldinger

et al. 2020

Ecology and Evolution

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“…3G) are capable of generating a bivariate distribution of hybrid indices, they continue to exhibit an excess of off-diagonal hybrids (as evidenced by the excess of simulated individuals with H o near 0.5) that fail to match our empirical data. However, high levels of immigration would also lead to emigration of hybrids into adjacent parental populations, likely accelerating hybrid zone expansion rather than narrowing it, an effect we did not consider in our model but which has been modeled and confirmed elsewhere (Irwin 2020). These results, together with the fact that we have a hybrid zone where hybridization is common, argues against strong premating isolation for our species pair but does not eliminate a secondary contribution of assortative mating to total reproductive isolation.…”

Section: Discussionmentioning

confidence: 66%

Postzygotic isolation drives genomic speciation between highly crypticHypocnemisantbirds from Amazonia

et al. 2020

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How species evolve reproductive isolation in the species-rich Amazon basin is poorly understood in vertebrates. Here, we sequenced a reference genome and used a genome-wide sample of SNPs to analyze a hybrid zone between two highly cryptic species of Hypocnemis warbling-antbirds-the Rondonia warbling-antbird (H. ochrogyna) and Spix's warbling-antbird (H. striata)-in a headwater region of southern Amazonia. We found that both species commonly hybridize, producing F 1 s and a variety of backcrosses with each species but we detected only one F 2-like hybrid. Patterns of heterozygosity, hybrid index, and interchromosomal linkage disequilibrium in hybrid populations closely match expectations under strong postzygotic isolation. Hybrid zone width (15.4 km) was much narrower than expected (211 km) indicating strong selection against hybrids. A remarkably high degree of concordance in cline centers and widths across loci, and a lack of reduced interspecific F st between populations close to versus far from the contact zone, suggest that genetic incompatibilities have rendered most of the genome immune to introgression. These results support intrinsic postzygotic isolation as a driver of speciation in a moderately young cryptic species pair from the Amazon and suggest that species richness of the Amazon may be grossly underestimated.

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“…Prezygotic isolation is common in nature, but the high prevalence of gene flow suggest that prezygotic barriers are leaky (Irwin 2019). Hybridization is a common occurrence in all taxa in which surveys have been systematically performed (Harrison and Larson 2014b;Mallet et al 2016;Taylor and Larson 2019).…”

Section: Discussionmentioning

confidence: 99%

Pure species discriminate against hybrids in theDrosophila melanogasterspecies subgroup

Serrato-Capuchina¹,

Schwochert²,

Zhang³

et al. 2020

Preprint

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Introgression, the exchange of alleles between species, is a common event in nature. This transfer of alleles between species must happen through fertile hybrids. Characterizing the traits that cause defects in hybrids illuminate how and when gene flow is expected to occur. Inviability and sterility are extreme examples of fitness reductions but are not the only type of defects in hybrids. Some traits specific to hybrids are more subtle but are important to determine their fitness. In this report, we study whether F1 hybrids between two species pairs of Drosophila are as attractive as the parental species. We find that in both species pairs, the sexual attractiveness of the F1 hybrids is reduced and that pure species discriminate strongly against them. We also find that the cuticular hydrocarbon (CHC) profile of the hybrids is intermediate between the parental species. Perfuming experiments show that modifying the CHC profile of the hybrids to resemble pure species improves their chances of mating. Our results show that behavioral discrimination against hybrids might be an important component of the persistence of species that can hybridize.

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Assortative Mating in Hybrid Zones Is Remarkably Ineffective in Promoting Speciation

Cited by 89 publications

References 91 publications

Implications for evolutionary trends from the pairing frequencies among golden‐winged and blue‐winged warblers and their hybrids

Implications for evolutionary trends from the pairing frequencies among golden‐winged and blue‐winged warblers and their hybrids

Postzygotic isolation drives genomic speciation between highly crypticHypocnemisantbirds from Amazonia

Pure species discriminate against hybrids in theDrosophila melanogasterspecies subgroup

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