ORIGINAL RESEARCH article
Front. Ecol. Evol.
Sec. Evolutionary Developmental Biology
Molecular Evolution of Floral Development Genes in Spiral Gingers with Divergent Pollination Syndromes
Provisionally accepted
- 1Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- 2Cornell University, Ithaca, United States
- 3Universidade de Brasilia, Brasília, Brazil
- 4Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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The evolution of floral traits is a key driver ofmajor contributor to plant diversification and pollination specialization. In the Neotropical genus Costus, closely related species exhibit distinct pollination syndromes that offer a unique, offering an opportunity to investigate the molecular underpinningsbasis of floral adaptation. We present the first comparative analysis of key floral developmental genes in two closely related spiral gingers with contrasting pollination syndromes: Costus bracteatus (bee-pollinated) and Costus zingiberoides (hummingbird-pollinated). Using newly generated genome assemblyassemblies, phylogenetic inference, positive selection analyses, and in silico protein modeling, we identified signatures of episodic positive selection in four genes, with AGL6 and CUC-like showing lineage-specific divergence in C. zingiberoides. Structural comparisons revealedindicated notable conformational differences, particularly in conserved domains such as the MADS-box and NAC domains, with alanine scanning highlighting both stabilizing and destabilizing mutations that may affect protein functionality. These results suggest that pollinator-driven selection has influenced the evolution of key floral genes in Costus, supporting a role for molecular adaptation in the repeated evolution of pollination syndromesOverall, evolutionarily significant divergence among floral developmental genes in these Costus lineages is concentrated at a limited number of sites rather than widespread across genes, suggesting that a small set of substitutions may contribute to differences in floral morphology, providing insights into the genetic architecture of floral diversification in monocots.
Keywords: Floral adaptation, flowering, MADS-box genes, monocots, natural selection
Received: 19 Nov 2025; Accepted: 26 Jan 2026.
Copyright: © 2026 de Jesus, Landis, Specht, André and Schrago. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Carlos G Schrago
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