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Mutualism disruption by an invasive ant reduces carbon fixation for a foundational East African ant-plant
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  • Patrick Milligan,
  • Timothy Martin,
  • Grace John,
  • Corinna Riginos,
  • Jacob Goheen,
  • Scott Carpenter,
  • Todd Palmer
Patrick Milligan
University of Florida
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Timothy Martin
University of Florida
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Grace John
University of Florida
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Corinna Riginos
The Nature Conservancy
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Jacob Goheen
Univ Wyoming
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Scott Carpenter
Yale University
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Todd Palmer
University of Florida
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Abstract

Invasive ants shape assemblages and interactions of native species, but their effect on fundamental ecological processes is poorly understood. In East Africa, Pheidole megacephala ants have invaded monodominant stands of the ant-tree Acacia drepanolobium, extirpating native ant defenders and rendering trees vulnerable to canopy damage by vertebrate herbivores. We used experiments and observations to quantify direct and interactive effects of invasive ants and large herbivores on A. drepanolobium photosynthesis over a 2-year period. Trees that had been invaded for ≥ 5 years exhibited 69% lower whole-tree photosynthesis during key growing seasons, resulting from interaction between invasive ants and vertebrate herbivores that caused leaf- and canopy-level photosynthesis declines. We also surveyed trees shortly before and after invasion, finding that recent invasion induced only minor changes in leaf physiology. Our results from individual trees likely scale up, highlighting the potential of invasive species to alter ecosystem-level carbon fixation and other biogeochemical cycles.

Peer review status:ACCEPTED

18 Jan 2021Submitted to Ecology Letters
19 Jan 2021Assigned to Editor
19 Jan 2021Submission Checks Completed
20 Jan 2021Reviewer(s) Assigned
10 Feb 2021Review(s) Completed, Editorial Evaluation Pending
16 Feb 2021Editorial Decision: Accept