Tradeoffs explain scaling, sex differences, and seasonal oscillations in the remarkable weapons of snapping shrimp (Alpheus spp.)

  1. Jason P Dinh  Is a corresponding author
  2. S N Patek
  1. Duke University, United States

Abstract

Evolutionary theory suggests that individuals should express costly traits at a magnitude that optimizes the cost-benefit difference for the trait-bearer. Trait expression varies across a species because costs and benefits vary among individuals. For example, if large individuals pay lower costs than small individuals, then larger individuals should reach optimal cost-benefit differences at a greater magnitude of trait expression. Using the remarkable cavitation-shooting weapons found in the big claws of male and female alpheid snapping shrimp, we test whether size- and sex-dependent expenditures explain the scaling of weapon size relative to body size and why males have larger proportional weapon size than females. We found that males and females from three snapping shrimp species (Alpheus heterochaelis, Alpheus angulosus, and Alpheus estuariensis) show patterns consistent with resource allocation tradeoffs between weapon and abdomen size. For male A. heterochaelis, the species for which we had the greatest sample size and statistical power, the smallest individuals showed the steepest tradeoff. Our extensive dataset in A. heterochaelis also included data about pairing, breeding season, and egg clutch size. Therefore, we could test for reproductive tradeoffs and benefits in this species. Female A. heterochaelis exhibited additional tradeoffs between weapon size and egg count, average egg volume, and total egg mass volume. For average egg volume, the smallest females exhibited the steepest tradeoff relative to weapon size. Furthermore, in males but not females, large weapons were positively correlated with the probability of being paired and the relative size of their pair mate. In conclusion, we establish that size-dependent tradeoffs underlie reliable scaling relationships of costly traits. Furthermore, we show that males and females differ in weapon investment, suggesting that weapons are especially beneficial to males and especially burdensome to females.

Data availability

Data, metadata, and code are available on Dryad: https://doi.org/10.5061/dryad.qz612jmkf

The following data sets were generated
The following previously published data sets were used

Article and author information

Author details

  1. Jason P Dinh

    Department of Biology, Duke University, Durham, United States
    For correspondence
    jasonpdinh@gmail.com
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6471-9047
  2. S N Patek

    Department of Biology, Duke University, Durham, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9738-882X

Funding

National Science Foundation (IOS 2019323)

  • S N Patek

National Science Foundation (DGE 2139754)

  • Jason P Dinh

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Lauren A O'Connell, Stanford University, United States

Version history

  1. Received: October 30, 2022
  2. Preprint posted: November 16, 2022 (view preprint)
  3. Accepted: April 20, 2023
  4. Accepted Manuscript published: May 9, 2023 (version 1)
  5. Version of Record published: June 1, 2023 (version 2)

Copyright

© 2023, Dinh & Patek

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Jason P Dinh
  2. S N Patek
(2023)
Tradeoffs explain scaling, sex differences, and seasonal oscillations in the remarkable weapons of snapping shrimp (Alpheus spp.)
eLife 12:e84589.
https://doi.org/10.7554/eLife.84589

Share this article

https://doi.org/10.7554/eLife.84589

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