A Complex Interplay Between Balancing Selection and Introgression Maintains a Genus-Wide Alternative Life History Strategy

Authors

Kalle Tunstrom, Stockholm University
Alyssa Woronik, Sacred Heart UniversityFollow
Joseph J. Hanly, George Washington University
Pasi Rastas, University of Helsinki
Anton Chichvarkhin, National Scientific Center of Marine Biology, Far Eastern Branch of Russian Academy of Sciences, Vladivostok
Andrew D. Warren, University of Florida
Akito Kawahara, University of Florida
Sean D. Schoville, University of Wisconsin
Vincent Ficarrotta, George Washington University
Adam H. Porter, University of Massachusetts Amherst
Ward B. Watt, University of South Carolina Columbia
Arnaud Martin, George Washington University
Christopher W. Wheat, Stockholm University

Document Type

Article

Publication Date

2021

Abstract

Alternative life-history strategies (ALHS) are genetic polymorphisms generating phenotypes differing in life histories that generally arise due to metabolic resource allocation tradeoffs. Although ALHS are often be limited to a single sex or populations of a species, they can, in rare cases, be found among several species across a genus. In the butterfly genus Colias, at least a third of the species have a female limited ALHS called Alba. While many females develop brightly pigmented wings, Alba females reallocate nitrogen resources used in pigment synthesis to reproductive development, producing white-winged, more fecund females. Whether this ALHS evolved once or many times, and whether it has moved among species via introgression or been maintained via long-term balancing selection, has not been established. Answering these questions presents an opportunity to investigate the genetic basis and evolutionary forces acting upon ALHS, which have rarely been studied at a genus level. Here we identify the genetic locus of Alba in a second Colias species, allowing us to compare this with previous results in a larger phylogenetic context. Our findings suggest Alba has a singular origin and has been maintained in Colias through a combination of balancing selection and introgression for nearly one million years and at least as many generations. Finally, using CRISPR/Cas9 deletions in the cis-regulatory region of the Alba allele, we demonstrate that the Alba allele is a modular enhancer for the BarH1 gene and is necessary for the induction of the ALHS, which potentially facilitates its long-term persistence in the genus.

Comments

This article is a preprint and has not been certified by peer review. Posted May 20, 2021.

DOI

10.1101/2021.05.20.445023

Recommended Citation

Tunstrom, K., Woronik, A., Hanly, J. J., Rastas, P., Chichvarkhin, A., Warren, A. D., Kawahara, A., ... & Wheat, C. W. (2021). A complex interplay between balancing selection and introgression maintains a genus-wide alternative life-history strategy. bioRxiv. doi: 10.1101/2021.05.20.445023

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.