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Why do understorey Licuala palm fruits turn from red to white and then black when ripe?
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  • Kenneth Er,
  • Derrick Nguyen,
  • Yi Shuen Yeoh,
  • Max Khoo,
  • Ruisheng Choo,
  • Li Si Tay,
  • Sun Yi Soh,
  • Zaki Jamil,
  • Wee Foong Ang,
  • Adrian Loo
Kenneth Er
National Parks Board
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Derrick Nguyen
National Parks Board
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Yi Shuen Yeoh
National Parks Board

Corresponding Author:wywyas@gmail.com

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Max Khoo
National Parks Board
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Ruisheng Choo
National Parks Board
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Li Si Tay
National Parks Board
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Sun Yi Soh
National Parks Board
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Zaki Jamil
National Parks Board
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Wee Foong Ang
National Parks Board
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Adrian Loo
National Parks Board
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Abstract

Licuala ferruginea Becc., a tropical forest understorey palm, is observed to have fruits that appear red in colour when unripe, turning pink, then white, purple and finally black in colour as they ripen. We monitored 13 fruiting palms in rainforest fragments and recorded the consumption of fruits by animals via camera traps. We also documented the fruiting phenology of two palms in the nursery. In the rainforest fragments, a Cream-vented Bulbul (Pycnonotus simplex) was observed plucking a mature purple fruit from a L. ferruginea palm, before flying away with the fruit in its beak. This was the only bird that was observed feeding on the mature fruit. A range of mammals, dominated by edge species such as the Long-tailed Macaque and Wild Boar, were observed to consume L. ferruginea fruits indiscriminately across all five colour stages, thereby limiting the dispersal of the fruits. Forest bulbul gape sizes also matched the fruit size, suggesting that forest bulbuls are the likely dispersers of the palm in the original forest where edge species are not in high densities. We further posit that the initial phase of red fruits, with high contrasting red reflectance against a green foliage background, might be a form of early advertisement to birds. The fruit then turns pink and white, which have high green reflectance and is less contrasting, thereby reducing the conspicuity of the fruit. This allows the fruit to ripen with high fructose and glucose content, and turn purple and black, which are known visual cues for birds. This study provides indicative support for the dispersal syndrome hypothesis and highlights the potential effects of forest fragmentation on plant-frugivore interactions. Keywords: Licuala, Arecaceae, dispersal syndrome, fruit, bulbul, reflectance
Submitted to Ecology and Evolution
Submission Checks Completed
Assigned to Editor
Reviewer(s) Assigned
11 Jul 2024Reviewer(s) Assigned
19 Jul 2024Review(s) Completed, Editorial Evaluation Pending
24 Jul 2024Editorial Decision: Revise Minor
07 Aug 20241st Revision Received
08 Aug 2024Submission Checks Completed
08 Aug 2024Assigned to Editor
08 Aug 2024Review(s) Completed, Editorial Evaluation Pending
16 Aug 2024Editorial Decision: Accept