Maria Gabriela G de Camargo1, H Martin Schaefer2, Gustavo Habermann3, Eliana Cazetta4, Natalia Costa Soares5, Leonor Patrícia C Morellato5. 1. Departamento de Botânica, Laboratório de Fenologia, Grupo de Fenologia e Dispersão de Sementes, Universidade Estadual Paulista, Avenida 24A 1515, CEP 13506-900, Rio Claro, SP, Brazil; fax: 55 19 3526-4201 gabicamargo@yahoo.com. 2. Department of Evolutionary Biology and Animal Ecology, Faculty of Biology, University of Freiburg, Hauptstr. 1 79104 Freiburg, Germany. 3. Departamento de Botânica, Instituto de Biociências, Universidade Estadual Paulista, Av. 24-A 1515, CEP 13506-900, Rio Claro, SP, Brazil; fax: 55 19 3526-4201. 4. Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Rodovia Jorge Amado km 16, CEP 45662-900, Ilhéus, BA, Brazil; fax: 55 73 3680 5226. 5. Departamento de Botânica, Laboratório de Fenologia, Grupo de Fenologia e Dispersão de Sementes, Universidade Estadual Paulista, Avenida 24A 1515, CEP 13506-900, Rio Claro, SP, Brazil; fax: 55 19 3526-4201.
Abstract
PREMISE OF THE STUDY: Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, signaling that fruits are ready to be consumed and dispersed. The color pattern for fruits of Miconia albicans (Melastomataceae), however, is the opposite, with reddish unripe and green ripe fruits. We (1) verified the maintenance over time of its bicolored display, (2) tested the communicative function of unripe fruits, (3) tested the photoprotective role of anthocyanins in unripe fruits, and (4) verified whether green ripe fruits can assimilate carbon. METHODS: Using a paired experiment, we tested whether detection of ripe fruits was higher on infructescences with unripe and ripe fruits compared with infructescences with only ripe fruits. We also measured and compared gas exchange, chlorophyll a fluorescence, and heat dissipation of covered (to prevent anthocyanin synthesis) and uncovered ripe and unripe fruits. KEY RESULTS: Although the bicolored display was maintained over time, unripe fruits had no influence on bird detection and removal of ripe fruits. Ripe and unripe fruits did not assimilate CO2, but they respired instead. CONCLUSIONS: Since the communicative function of unripe fruits was not confirmed, seed dispersers are unlikely to select the display with bicolored fruits. Because of the absence of photosynthetic activity in ripe and unripe fruits and enhanced photoprotective mechanisms in ripe fruits rather than in unripe fruits, we could not confirm the photoprotective role of anthocyanins in unripe fruits. As an alternative hypothesis, we suggest that the bicolored fruit display could be an adaptation to diversify seed dispersal vectors instead of restricting dispersal to birds and that anthocyanins in unripe fruits may have a defense role against pathogens.
PREMISE OF THE STUDY: Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, signaling that fruits are ready to be consumed and dispersed. The color pattern for fruits of Miconia albicans (Melastomataceae), however, is the opposite, with reddish unripe and green ripe fruits. We (1) verified the maintenance over time of its bicolored display, (2) tested the communicative function of unripe fruits, (3) tested the photoprotective role of anthocyanins in unripe fruits, and (4) verified whether green ripe fruits can assimilate carbon. METHODS: Using a paired experiment, we tested whether detection of ripe fruits was higher on infructescences with unripe and ripe fruits compared with infructescences with only ripe fruits. We also measured and compared gas exchange, chlorophyll a fluorescence, and heat dissipation of covered (to prevent anthocyanin synthesis) and uncovered ripe and unripe fruits. KEY RESULTS: Although the bicolored display was maintained over time, unripe fruits had no influence on bird detection and removal of ripe fruits. Ripe and unripe fruits did not assimilate CO2, but they respired instead. CONCLUSIONS: Since the communicative function of unripe fruits was not confirmed, seed dispersers are unlikely to select the display with bicolored fruits. Because of the absence of photosynthetic activity in ripe and unripe fruits and enhanced photoprotective mechanisms in ripe fruits rather than in unripe fruits, we could not confirm the photoprotective role of anthocyanins in unripe fruits. As an alternative hypothesis, we suggest that the bicolored fruit display could be an adaptation to diversify seed dispersal vectors instead of restricting dispersal to birds and that anthocyanins in unripe fruits may have a defense role against pathogens.
Authors: João Vitor S Messeder; Fernando A O Silveira; Tatiana G Cornelissen; Lisieux F Fuzessy; Tadeu J Guerra Journal: Ann Bot Date: 2021-04-17 Impact factor: 4.357