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Morning glory species co-occurrence is associated with asymmetrically decreased and cascading reproductive isolation.

Publication ,  Journal Article
Ostevik, KL; Rifkin, JL; Xia, H; Rausher, MD
Published in: Evolution letters
February 2021

Hybridization between species can affect the strength of the reproductive barriers that separate those species. Two extensions of this effect are (1) the expectation that asymmetric hybridization or gene flow will have asymmetric effects on reproductive barrier strength and (2) the expectation that local hybridization will affect only local reproductive barrier strength and could therefore alter within-species compatibility. We tested these hypotheses in a pair of morning glory species that exhibit asymmetric gene flow from highly selfing Ipomoea lacunosa into mixed-mating Ipomoea cordatotriloba in regions where they co-occur. Because of the direction of this gene flow, we predicted that reproductive barrier strength would be more strongly affected in I. cordatotriloba than I. lacunosa. We also predicted that changes to reproductive barriers in sympatric I. cordatotriloba populations would affect compatibility with allopatric populations of that species. We tested these predictions by measuring the strength of a reproductive barrier to seed set across the species' ranges. Consistent with our first prediction, we found that sympatric and allopatric I. lacunosa produce the same number of seeds in crosses with I. cordatotriloba, whereas crosses between sympatric I. cordatotriloba and I. lacunosa are more successful than crosses between allopatric I. cordatotriloba and I. lacunosa. This difference in compatibility appears to reflect an asymmetric decrease in the strength of the barrier to seed set in sympatric I. cordatotriloba, which could be caused by I. lacunosa alleles that have introgressed into I. cordatotriloba. We further demonstrated that changes to sympatric I. cordatotriloba have decreased its ability to produce seeds with allopatric populations of the same species, in line with our second prediction. Thus, in a manner analogous to cascade reinforcement, we suggest that introgression associated with hybridization not only influences between-species isolation but can also contribute to isolation within a species.

Duke Scholars

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Published In

Evolution letters

DOI

EISSN

2056-3744

ISSN

2056-3744

Publication Date

February 2021

Volume

5

Issue

1

Start / End Page

75 / 85

Related Subject Headings

  • 3104 Evolutionary biology
 

Citation

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Ostevik, K. L., Rifkin, J. L., Xia, H., & Rausher, M. D. (2021). Morning glory species co-occurrence is associated with asymmetrically decreased and cascading reproductive isolation. Evolution Letters, 5(1), 75–85. https://doi.org/10.1002/evl3.205
Ostevik, Kate L., Joanna L. Rifkin, Hanhan Xia, and Mark D. Rausher. “Morning glory species co-occurrence is associated with asymmetrically decreased and cascading reproductive isolation.Evolution Letters 5, no. 1 (February 2021): 75–85. https://doi.org/10.1002/evl3.205.
Ostevik KL, Rifkin JL, Xia H, Rausher MD. Morning glory species co-occurrence is associated with asymmetrically decreased and cascading reproductive isolation. Evolution letters. 2021 Feb;5(1):75–85.
Ostevik, Kate L., et al. “Morning glory species co-occurrence is associated with asymmetrically decreased and cascading reproductive isolation.Evolution Letters, vol. 5, no. 1, Feb. 2021, pp. 75–85. Epmc, doi:10.1002/evl3.205.
Ostevik KL, Rifkin JL, Xia H, Rausher MD. Morning glory species co-occurrence is associated with asymmetrically decreased and cascading reproductive isolation. Evolution letters. 2021 Feb;5(1):75–85.
Journal cover image

Published In

Evolution letters

DOI

EISSN

2056-3744

ISSN

2056-3744

Publication Date

February 2021

Volume

5

Issue

1

Start / End Page

75 / 85

Related Subject Headings

  • 3104 Evolutionary biology