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Reproductive character displacement and underlying drivers in a species-rich and florally diverse lineage of tropical angiosperms (Ruellia; Acanthaceae)
  • Erin Tripp,
  • Kyle G. Dexter,
  • Heather Stone
Erin Tripp
University of Colorado
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Kyle G. Dexter
The University of Edinburgh
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Heather Stone
University of Colorado at Boulder
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Peer review status:IN REVISION

13 Jan 2020Submitted to Ecology and Evolution
14 Jan 2020Submission Checks Completed
14 Jan 2020Assigned to Editor
14 Jan 2020Reviewer(s) Assigned
04 Feb 2020Review(s) Completed, Editorial Evaluation Pending
10 Feb 2020Editorial Decision: Revise Minor
16 Jul 20201st Revision Received
16 Jul 2020Submission Checks Completed
16 Jul 2020Assigned to Editor
16 Jul 2020Review(s) Completed, Editorial Evaluation Pending
16 Jul 2020Reviewer(s) Assigned
10 Aug 2020Editorial Decision: Revise Minor

Abstract

Reproductive character displacement is a pattern whereby sympatric lineages diverge more in reproductive character morphology than allopatric lineages. This pattern has been observed in many plant species, but comparably few have sought to disentangle underlying mechanisms. Here, in a hyperdiverse lineage of Neotropical plants (Ruellia; Acanthaceae), we present evidence of reproductive character displacement in a macroevolutionary framework (i.e., among species) and document mechanistic underpinnings. In a series of inter-specific hand pollinations in a controlled glasshouse environment, we found that crosses between species that differed more in overall flower size, particularly in style length, were significantly less likely to produce viable seeds. Further, species pairs that failed to set seed were more likely to have sympatric distributions in nature. While these findings could result from competition for pollinators or differential fusion of sympatric populations based on variable crossability, our results instead lend support for a role of reinforcement whereby selection has acted to increase reproductive barriers between sympatric species, especially given divergence in floral traits less likely to be under selection by pollinators (i.e., style length). Our results add to growing evidence that character displacement contributes to exceptional floral diversity of angiosperms.