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The trade-off between investment in weapons and fertility is mediated through spermatogenesis in the leaf-footed cactus bug Narnia femorata
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  • Katelyn Cavender,
  • Tessa Ricker,
  • Mackenzie Lyon,
  • Emily Shelby,
  • Christine Miller,
  • Patricia Moore
Katelyn Cavender
University of Georgia College of Agricultural and Environmental Sciences
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Tessa Ricker
University of Florida College of Agricultural and Life Sciences
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Mackenzie Lyon
University of Georgia College of Agricultural and Environmental Sciences
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Emily Shelby
University of Georgia College of Agricultural and Environmental Sciences
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Christine Miller
University of Florida College of Agricultural and Life Sciences
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Patricia Moore
University of Georgia College of Agricultural and Environmental Sciences
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Abstract

Males have the ability to compete for fertilizations through both pre-copulatory and post-copulatory intrasexual competition. Pre-copulatory competition has selected for large weapons and other adaptations to maximize access to females and mating opportunities while post-copulatory competition has resulted in ejaculate adaptations to maximize fertilization success. Negative associations between these strategies support the hypothesis that there is a trade-off between success at pre- and post-copulatory mating success. Recently, this trade-off has been demonstrated with experimental manipulation. Male leaf-footed cactus bugs, Narnia femorata, that lose a weapon by autotomy during development invest instead in large testes. While evolutionary outcomes of the trade-offs between pre- and post-copulatory strategies have been identified, less work has been done to identify proximate mechanisms by which the trade-off might occur, perhaps because the systems in which the trade-offs have been investigated are not ones that have the molecular tools required for exploring mechanism. Here we applied knowledge from a related model species for which we have developmental knowledge and molecular tools, the milkweed bug Oncopeltus fasciatus, to investigate the proximate mechanism by which autotomized N. femorata males developed larger testes. Autotomized males had evidence of a higher rate of transit amplification divisions in the spermatogonia, which would result in greater sperm numbers. Identification of mechanisms underlying a trade-off can help our understanding of the direction and constraints on evolutionary trajectories and thus the evolutionary potential under multiple forms of selection.

Peer review status:ACCEPTED

22 Dec 2020Submitted to Ecology and Evolution
24 Dec 2020Submission Checks Completed
24 Dec 2020Assigned to Editor
12 Jan 2021Reviewer(s) Assigned
09 Feb 2021Review(s) Completed, Editorial Evaluation Pending
22 Feb 2021Editorial Decision: Revise Minor
05 Mar 20211st Revision Received
08 Mar 2021Submission Checks Completed
08 Mar 2021Assigned to Editor
08 Mar 2021Review(s) Completed, Editorial Evaluation Pending
16 Mar 2021Editorial Decision: Accept