Journal article
Does getting defensive get you anywhere?-Seasonal balancing selection, temperature, and parasitoids shape real-world, protective endosymbiont dynamics in the pea aphid
Molecular ecology, v 30(10), pp 2449-2472
01 May 2021
PMID: 33876478
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Facultative, heritable endosymbionts are found at intermediate prevalence within most insect species, playing frequent roles in their hosts' defence against environmental pressures. Focusing on Hamiltonella defensa, a common bacterial endosymbiont of aphids, we tested the hypothesis that such pressures impose seasonal balancing selection, shaping a widespread infection polymorphism. In our studied pea aphid (Acyrthosiphon pisum) population, Hamiltonella frequencies ranged from 23.2% to 68.1% across a six-month longitudinal survey. Rapid spikes and declines were often consistent across fields, and we estimated that selection coefficients for Hamiltonella-infected aphids changed sign within this field season. Prior laboratory research suggested antiparasitoid defence as the major Hamiltonella benefit, and costs under parasitoid absence. While a prior field study suggested these forces can sometimes act as counter-weights in a regime of seasonal balancing selection, our present survey showed no significant relationship between parasitoid wasps and Hamiltonella prevalence. Field cage experiments provided some explanation: parasitoids drove modest similar to 10% boosts to Hamiltonella frequencies that would be hard to detect under less controlled conditions. They also showed that Hamiltonella was not always costly under parasitoid exclusion, contradicting another prediction. Instead, our longitudinal survey - and two overwintering studies - showed temperature to be the strongest predictor of Hamiltonella prevalence. Matching some prior lab discoveries, this suggested that thermally sensitive costs and benefits, unrelated to parasitism, can shape Hamiltonella dynamics. These results add to a growing body of evidence for rapid, seasonal adaptation in multivoltine organisms, suggesting that such adaptation can be mediated through the diverse impacts of heritable bacterial endosymbionts.
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Details
- Title
- Does getting defensive get you anywhere?-Seasonal balancing selection, temperature, and parasitoids shape real-world, protective endosymbiont dynamics in the pea aphid
- Creators
- Andrew H. Smith - Drexel UniversityMichael P. O'Connor - Drexel UniversityBrooke Deal - Drexel UniversityColeman Kotzer - Drexel UniversityAmanda Lee - Drexel UniversityBarrett Wagner - Drexel UniversityJonah Joffe - Drexel UniversityStephen Woloszynek - Drexel UniversityKerry M. Oliver - University of Georgia PressJacob A. Russell - Drexel University
- Publication Details
- Molecular ecology, v 30(10), pp 2449-2472
- Publisher
- Wiley
- Number of pages
- 24
- Grant note
- 1050098; 1754597; 1050128; 1754302 / NSF; National Science Foundation (NSF)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biodiversity, Earth, and Environmental Science (BEES); Microbiology and Immunology; Biology
- Web of Science ID
- WOS:000641236700001
- Scopus ID
- 2-s2.0-85104434593
- Other Identifier
- 991019169803204721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Biochemistry & Molecular Biology
- Ecology
- Evolutionary Biology