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Geographic variation in hybridization across a reinforcement contact zone of chorus frogs (Pseudacris)

Title: Geographic variation in hybridization across a reinforcement contact zone of chorus frogs (Pseudacris).
Name(s): Lemmon, Emily Moriarty, author
Juenger, Thomas E., author
Type of Resource: text
Genre: Text
Journal Article
Date Issued: 2017-10-11
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Reinforcement contact zones, which are secondary contact zones where species are diverging in reproductive behaviors due to selection against hybridization, represent natural laboratories for studying speciation-in-action. Here, we examined replicate localities across the entire reinforcement contact zone between North American chorus frogs Pseudacris feriarum and P. nigrita to investigate geographic variation in hybridization frequencies and to assess whether reinforcement may have contributed to increased genetic divergence within species. Previous work indicated these species have undergone reproductive character displacement (RCD) in male acoustic signals and female preferences due to reinforcement. We also examined acoustic signal variation across the contact zone to assess whether signal characteristics reliably predict hybrid index and to elucidate whether the degree of RCD predicts hybridization rate. Using microsatellites, mitochondrial sequences, and acoustic signal information from >1,000 individuals across >50 localities and ten sympatric focal regions, we demonstrate: (1) hybridization occurs and (2) varies substantially across the geographic range of the contact zone, (3) hybridization is asymmetric and in the direction predicted from observed patterns of asymmetric RCD, (4) in one species, genetic distance is higher between conspecific localities where one or both have been reinforced than between nonreinforced localities, after controlling for geographic distance, (5) acoustic signal characters strongly predict hybrid index, and (6) the degree of RCD does not strongly predict admixture levels. By showing that hybridization occurs in all sympatric localities, this study provides the fifth and final line of evidence that reproductive character displacement is due to reinforcement in the chorus frog contact zone. Furthermore, this work suggests that the dual action of cascade reinforcement and partial geographic isolation is promoting genetic diversification within one of the reinforced species.
Identifier: FSU_libsubv1_scholarship_submission_1518810795_fea4fd92 (IID), 10.1002/ece3.3443 (DOI)
Keywords: Acoustic signal, Cascade reinforcement, Hybridization, Reproductive character displacement
Publication Note: © 2017 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Grant Number: DEB #0546316, DEB #9981631, DEB #1120516
Persistent Link to This Record:
Use and Reproduction: Creative Commons Attribution (CC BY 4.0)
Owner Institution: FSU
Is Part Of: Ecology and Evolution.
Issue: iss. 22, vol. 7

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Lemmon, E. M., & Juenger, T. E. (2017). Geographic variation in hybridization across a reinforcement contact zone of chorus frogs (Pseudacris). Ecology And Evolution. Retrieved from