Propagule size and sex ratio influence colonisation dynamics after introduction of a non-native lizard

Amélie Fargevieille, Aaron M. Reedy, Ariel F. Kahrl, Timothy S. Mitchell, Andrew M. Durso, David M. Delaney, Phillip R. Pearson, Robert M. Cox, Daniel A. Warner

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The composition of founding populations plays an important role in colonisation dynamics and can influence population growth during early stages of biological invasion. Specifically, founding populations with small propagules (i.e. low number of founders) are vulnerable to the Allee effect and have reduced likelihood of establishment compared to those with large propagules. The founding sex ratio can also impact establishment via its influence on mating success and offspring production. Our goal was to test the effects of propagule size and sex ratio on offspring production and annual population growth following introductions of a non-native lizard species (Anolis sagrei). We manipulated propagule composition on nine small islands, then examined offspring production, population growth and survival rate of founders and their descendants encompassing three generations. By the third reproductive season, per capita offspring production was higher on islands seeded with a relatively large propagule size, but population growth was not associated with propagule size. Propagule sex ratio did not affect offspring production, but populations with a female-biased propagule had positive growth, whereas those with a male-biased propagule had negative growth in the first year. Populations were not affected by propagule sex ratio in subsequent years, possibly due to rapid shifts towards balanced (or slightly female biased) population sex ratios. Overall, we show that different components of population fitness have different responses to propagule size and sex ratio in ways that could affect early stages of biological invasion. Despite these effects, the short life span and high fecundity of A. sagrei likely helped small populations to overcome Allee effects and enabled all populations to successfully establish. Our rare experimental manipulation of propagule size and sex ratio can inform predictions of colonisation dynamics in response to different compositions of founding populations, which is critical in the context of population ecology and invasion dynamics.

Original languageEnglish (US)
Pages (from-to)845-857
Number of pages13
JournalJournal of Animal Ecology
Volume91
Issue number4
DOIs
StatePublished - Apr 2022

Bibliographical note

Funding Information:
Thanks to the Eppley Foundation for Research, National Geographic Society, the Waitt Foundation, the American Philosophical Society, the University of Alabama at Birmingham, and Auburn University for funding this research. We are grateful to Alexis Harrison helping initiate this work and numerous undergraduate students for assistance in the field. Comments on earlier drafts from two anonymous reviewers and Dr. William Morgan helped improve this paper. This research was approved by the University of Alabama at Birmingham Institutional Animal Care and Use Committee (protocol: 130709913), the FL Department of Environmental Protection (permit# 12111213), and the Guana Tolomato Matanzas National Estuarine Research Reserve. This is manuscript #918 of the Auburn University Museum of Natural History.

Funding Information:
Thanks to the Eppley Foundation for Research, National Geographic Society, the Waitt Foundation, the American Philosophical Society, the University of Alabama at Birmingham, and Auburn University for funding this research. We are grateful to Alexis Harrison helping initiate this work and numerous undergraduate students for assistance in the field. Comments on earlier drafts from two anonymous reviewers and Dr. William Morgan helped improve this paper. This research was approved by the University of Alabama at Birmingham Institutional Animal Care and Use Committee (protocol: 130709913), the FL Department of Environmental Protection (permit# 12111213), and the Guana Tolomato Matanzas National Estuarine Research Reserve. This is manuscript #918 of the Auburn University Museum of Natural History.

Publisher Copyright:
© 2022 British Ecological Society.

Keywords

  • Allee effect
  • Anolis sagrei
  • biological invasion
  • invasive species
  • population establishment
  • population estimation
  • population growth

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