Skip to main content
bioRxiv
  • Home
  • About
  • Submit
  • ALERTS / RSS
Advanced Search
New Results

Supergene degeneration opposes polymorphism: The curious case of balanced lethals

View ORCID ProfileEmma L. Berdan, View ORCID ProfileAlexandre Blanckaert, View ORCID ProfileRoger K. Butlin, View ORCID ProfileThomas Flatt, View ORCID ProfileTanja Slotte, View ORCID ProfileBen Wielstra
doi: https://doi.org/10.1101/2021.11.27.470204
Emma L. Berdan
1Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, The Netherlands
2Institute of Biology Leiden, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands
3Tjärnö Marine Laboratory, Department of Marine Sciences, University of Gothenburg, 45296 Strömstad, Sweden
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • ORCID record for Emma L. Berdan
  • For correspondence: emma.berdan@gmail.com
Alexandre Blanckaert
4Laboratory of Genetics, University of Wisconsin-Madison Madison WI, USA
5cE3c – Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • ORCID record for Alexandre Blanckaert
Roger K. Butlin
3Tjärnö Marine Laboratory, Department of Marine Sciences, University of Gothenburg, 45296 Strömstad, Sweden
6Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • ORCID record for Roger K. Butlin
Thomas Flatt
7Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • ORCID record for Thomas Flatt
Tanja Slotte
8Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • ORCID record for Tanja Slotte
Ben Wielstra
1Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, The Netherlands
2Institute of Biology Leiden, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • ORCID record for Ben Wielstra
  • Abstract
  • Full Text
  • Info/History
  • Metrics
  • Supplementary material
  • Data/Code
  • Preview PDF
Loading

Abstract

Supergenes offer some of the most spectacular examples of long-term balancing selection in nature but their origin and maintenance remain a mystery. A critical aspect of supergenes is reduced recombination between arrangements. Reduced recombination protects adaptive multi-trait phenotypes, but can also lead to degeneration through mutation accumulation. Mutation accumulation can stabilize the system through the emergence of associative overdominance (AOD), destabilize the system, or lead to new evolutionary outcomes. One such outcome is the formation of balanced lethal systems, a maladaptive system where both supergene arrangements have accumulated deleterious mutations to the extent that both homozygotes are inviable, leaving only heterozygotes to reproduce. Here, we perform a simulation study to understand the conditions under which these different outcomes occur, assuming a scenario of introgression after allopatric divergence. We found that AOD aids the invasion of a new supergene arrangement and the establishment of a polymorphism. However, this polymorphism is easily destabilized by further mutation accumulation. While degradation may strengthen AOD, thereby stabilizing the supergene polymorphism, it is often asymmetric, which is the key disrupter of the quasi-equilibrium state of the polymorphism. Furthermore, mechanisms that accelerate degeneration also tend to amplify asymmetric mutation accumulation between the supergene arrangements and vice versa. As the evolution of a balanced lethal system requires symmetric degradation of both arrangements, this leaves highly restricted conditions under which such a system could evolve. We show that small population size and low dominance coefficients are critical factors, as these reduce the efficacy of selection. The dichotomy between the persistence of a polymorphism and degradation of supergene arrangements likely underlies the rarity of balanced lethal systems in nature.

Competing Interest Statement

The authors have declared no competing interest.

Footnotes

  • https://gitlab.com/slottelab/BL_sims

Copyright 
The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license.
Back to top
PreviousNext
Posted November 28, 2021.
Download PDF

Supplementary Material

Data/Code
Email

Thank you for your interest in spreading the word about bioRxiv.

NOTE: Your email address is requested solely to identify you as the sender of this article.

Enter multiple addresses on separate lines or separate them with commas.
Supergene degeneration opposes polymorphism: The curious case of balanced lethals
(Your Name) has forwarded a page to you from bioRxiv
(Your Name) thought you would like to see this page from the bioRxiv website.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Share
Supergene degeneration opposes polymorphism: The curious case of balanced lethals
Emma L. Berdan, Alexandre Blanckaert, Roger K. Butlin, Thomas Flatt, Tanja Slotte, Ben Wielstra
bioRxiv 2021.11.27.470204; doi: https://doi.org/10.1101/2021.11.27.470204
Reddit logo Twitter logo Facebook logo LinkedIn logo Mendeley logo
Citation Tools
Supergene degeneration opposes polymorphism: The curious case of balanced lethals
Emma L. Berdan, Alexandre Blanckaert, Roger K. Butlin, Thomas Flatt, Tanja Slotte, Ben Wielstra
bioRxiv 2021.11.27.470204; doi: https://doi.org/10.1101/2021.11.27.470204

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Subject Area

  • Evolutionary Biology
Subject Areas
All Articles
  • Animal Behavior and Cognition (4384)
  • Biochemistry (9610)
  • Bioengineering (7104)
  • Bioinformatics (24897)
  • Biophysics (12632)
  • Cancer Biology (9974)
  • Cell Biology (14373)
  • Clinical Trials (138)
  • Developmental Biology (7966)
  • Ecology (12126)
  • Epidemiology (2067)
  • Evolutionary Biology (16002)
  • Genetics (10936)
  • Genomics (14756)
  • Immunology (9880)
  • Microbiology (23698)
  • Molecular Biology (9490)
  • Neuroscience (50924)
  • Paleontology (370)
  • Pathology (1541)
  • Pharmacology and Toxicology (2687)
  • Physiology (4023)
  • Plant Biology (8674)
  • Scientific Communication and Education (1511)
  • Synthetic Biology (2402)
  • Systems Biology (6444)
  • Zoology (1346)