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Assessing the impact of deforestation of the Atlantic rainforest on ant-fruit interactions: a field experiment using synthetic fruits.

Bieber AG, Silva PS, Sendoya SF, Oliveira PS - PLoS ONE (2014)

Bottom Line: Large species (≥3 mm) of Pheidole (Myrmicinae), also able to remove fruits, did not differ between forest types.Moreover, displacement distances were also greater in the undisturbed forests.Together with the severe loss of their primary dispersers in human-disturbed tropical forest sites, vertebrate-dispersed fruits may also be deprived of potential ant-derived benefits in these habitats due to shifts in the composition of interacting ant species.

View Article: PubMed Central - PubMed

Affiliation: Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas SP, Brazil.

ABSTRACT
Ants frequently interact with fleshy fruits on the ground of tropical forests. This interaction is regarded as mutualistic because seeds benefit from enhanced germination and dispersal to nutrient-rich microsites, whereas ants benefit from consuming the nutritious pulp/aril. Considering that the process of deforestation affects many attributes of the ecosystem such as species abundance and composition, and interspecific interactions, we asked whether the interaction between ants and fallen fleshy fruits in the Brazilian Atlantic forest differs between human-created fragments and undisturbed forests. We controlled diaspore type and quantity by using synthetic fruits (a plastic 'seed' covered by a lipid-rich 'pulp'), which were comparable to lipid-rich fruits. Eight independent areas (four undisturbed forests, and four disturbed forest fragments) were used in the field experiment, in which we recorded the attracted ant species, ant behaviour, and fruit removal distance. Fruits in undisturbed forest sites attracted a higher number of species than those in disturbed forests. Moreover, the occurrence of large, fruit-carrying ponerine ants (Pachycondyla, Odontomachus; 1.1 to 1.4 cm) was higher in undisturbed forests. Large species (≥3 mm) of Pheidole (Myrmicinae), also able to remove fruits, did not differ between forest types. Following these changes in species occurrence, fruit displacement was more frequent in undisturbed than in disturbed forests. Moreover, displacement distances were also greater in the undisturbed forests. Our data suggest that fallen fleshy fruits interacting with ants face different fates depending on the conservation status of the forest. Together with the severe loss of their primary dispersers in human-disturbed tropical forest sites, vertebrate-dispersed fruits may also be deprived of potential ant-derived benefits in these habitats due to shifts in the composition of interacting ant species. Our data illustrate the use of synthetic fruits to better understand the ecology of ant-fruit interactions in variable ecological settings, including human-disturbed landscapes.

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Ant attendance and ant behaviour toward synthetic fruits.(A) Occurrence of particular ant groups and (B) occurrence of beneficial behaviours at sampling stations. Experiments with synthetic fruits were carried out in two diverging forest types in the Atlantic forest, Southeast Brazil, undisturbed (white circles; four sites) and fragmented forest sites (gray circles; four sites). The ant groups (large ponerines and large Pheidole spp.) were those whose behaviours were considered as potentially beneficial to ‘seeds’ (either removing the entire ‘fruit’ or cleaning the ‘pulp’ in situ) during the 22-hour experiment. The number of stations (y-axis) in (B) corresponds to those stations having at least one of the five seeds either removed or cleaned by ants. Asterisks indicate significant differences (p<0.5) between forest types.
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pone-0090369-g005: Ant attendance and ant behaviour toward synthetic fruits.(A) Occurrence of particular ant groups and (B) occurrence of beneficial behaviours at sampling stations. Experiments with synthetic fruits were carried out in two diverging forest types in the Atlantic forest, Southeast Brazil, undisturbed (white circles; four sites) and fragmented forest sites (gray circles; four sites). The ant groups (large ponerines and large Pheidole spp.) were those whose behaviours were considered as potentially beneficial to ‘seeds’ (either removing the entire ‘fruit’ or cleaning the ‘pulp’ in situ) during the 22-hour experiment. The number of stations (y-axis) in (B) corresponds to those stations having at least one of the five seeds either removed or cleaned by ants. Asterisks indicate significant differences (p<0.5) between forest types.

Mentions: Two large ponerines, Pachycondyla striata and Odontomachus chelifer, and a few large species of Pheidole (Myrmicinae) were amongst the most frequent removers of synthetic fruits (see Figure 2 and Table S1). The ant species most commonly seen cleaning the ‘pulp’ from synthetic fruits were Megalomyrmex iheringi, Solenopsis sp. 11, and a few Pheidole species. However, most ant species (70%), especially the small ones, were neither capable of displacing synthetic fruits nor of entirely detaching the synthetic pulp (see Table S1). Field observations revealed that large ponerines and large Pheidole were the ants most likely to provide beneficial services to ‘seeds’ (i.e., dispersal, or ‘pulp’ detaching). Pachycondyla striata and Odontomachus chelifer were the main removers of synthetic diaspores and their presence was higher in undisturbed forest sites than in disturbed areas (Wald's Z = −2.03, p<0.05; Figure 5A). On the other hand, large species of Pheidole (body length ≥3 mm) were frequently seen performing ‘seed’ cleaning on spot and/or ‘fruit’ displacement. This myrmicine group was equally frequent in undisturbed and disturbed forests (Wald's Z = −1.09, p = 0.28; Figure 5A) (Zadjusted  = 0.88, p = 0.38) (see Figure 5A and Table S1).


Assessing the impact of deforestation of the Atlantic rainforest on ant-fruit interactions: a field experiment using synthetic fruits.

Bieber AG, Silva PS, Sendoya SF, Oliveira PS - PLoS ONE (2014)

Ant attendance and ant behaviour toward synthetic fruits.(A) Occurrence of particular ant groups and (B) occurrence of beneficial behaviours at sampling stations. Experiments with synthetic fruits were carried out in two diverging forest types in the Atlantic forest, Southeast Brazil, undisturbed (white circles; four sites) and fragmented forest sites (gray circles; four sites). The ant groups (large ponerines and large Pheidole spp.) were those whose behaviours were considered as potentially beneficial to ‘seeds’ (either removing the entire ‘fruit’ or cleaning the ‘pulp’ in situ) during the 22-hour experiment. The number of stations (y-axis) in (B) corresponds to those stations having at least one of the five seeds either removed or cleaned by ants. Asterisks indicate significant differences (p<0.5) between forest types.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3936012&req=5

pone-0090369-g005: Ant attendance and ant behaviour toward synthetic fruits.(A) Occurrence of particular ant groups and (B) occurrence of beneficial behaviours at sampling stations. Experiments with synthetic fruits were carried out in two diverging forest types in the Atlantic forest, Southeast Brazil, undisturbed (white circles; four sites) and fragmented forest sites (gray circles; four sites). The ant groups (large ponerines and large Pheidole spp.) were those whose behaviours were considered as potentially beneficial to ‘seeds’ (either removing the entire ‘fruit’ or cleaning the ‘pulp’ in situ) during the 22-hour experiment. The number of stations (y-axis) in (B) corresponds to those stations having at least one of the five seeds either removed or cleaned by ants. Asterisks indicate significant differences (p<0.5) between forest types.
Mentions: Two large ponerines, Pachycondyla striata and Odontomachus chelifer, and a few large species of Pheidole (Myrmicinae) were amongst the most frequent removers of synthetic fruits (see Figure 2 and Table S1). The ant species most commonly seen cleaning the ‘pulp’ from synthetic fruits were Megalomyrmex iheringi, Solenopsis sp. 11, and a few Pheidole species. However, most ant species (70%), especially the small ones, were neither capable of displacing synthetic fruits nor of entirely detaching the synthetic pulp (see Table S1). Field observations revealed that large ponerines and large Pheidole were the ants most likely to provide beneficial services to ‘seeds’ (i.e., dispersal, or ‘pulp’ detaching). Pachycondyla striata and Odontomachus chelifer were the main removers of synthetic diaspores and their presence was higher in undisturbed forest sites than in disturbed areas (Wald's Z = −2.03, p<0.05; Figure 5A). On the other hand, large species of Pheidole (body length ≥3 mm) were frequently seen performing ‘seed’ cleaning on spot and/or ‘fruit’ displacement. This myrmicine group was equally frequent in undisturbed and disturbed forests (Wald's Z = −1.09, p = 0.28; Figure 5A) (Zadjusted  = 0.88, p = 0.38) (see Figure 5A and Table S1).

Bottom Line: Large species (≥3 mm) of Pheidole (Myrmicinae), also able to remove fruits, did not differ between forest types.Moreover, displacement distances were also greater in the undisturbed forests.Together with the severe loss of their primary dispersers in human-disturbed tropical forest sites, vertebrate-dispersed fruits may also be deprived of potential ant-derived benefits in these habitats due to shifts in the composition of interacting ant species.

View Article: PubMed Central - PubMed

Affiliation: Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas SP, Brazil.

ABSTRACT
Ants frequently interact with fleshy fruits on the ground of tropical forests. This interaction is regarded as mutualistic because seeds benefit from enhanced germination and dispersal to nutrient-rich microsites, whereas ants benefit from consuming the nutritious pulp/aril. Considering that the process of deforestation affects many attributes of the ecosystem such as species abundance and composition, and interspecific interactions, we asked whether the interaction between ants and fallen fleshy fruits in the Brazilian Atlantic forest differs between human-created fragments and undisturbed forests. We controlled diaspore type and quantity by using synthetic fruits (a plastic 'seed' covered by a lipid-rich 'pulp'), which were comparable to lipid-rich fruits. Eight independent areas (four undisturbed forests, and four disturbed forest fragments) were used in the field experiment, in which we recorded the attracted ant species, ant behaviour, and fruit removal distance. Fruits in undisturbed forest sites attracted a higher number of species than those in disturbed forests. Moreover, the occurrence of large, fruit-carrying ponerine ants (Pachycondyla, Odontomachus; 1.1 to 1.4 cm) was higher in undisturbed forests. Large species (≥3 mm) of Pheidole (Myrmicinae), also able to remove fruits, did not differ between forest types. Following these changes in species occurrence, fruit displacement was more frequent in undisturbed than in disturbed forests. Moreover, displacement distances were also greater in the undisturbed forests. Our data suggest that fallen fleshy fruits interacting with ants face different fates depending on the conservation status of the forest. Together with the severe loss of their primary dispersers in human-disturbed tropical forest sites, vertebrate-dispersed fruits may also be deprived of potential ant-derived benefits in these habitats due to shifts in the composition of interacting ant species. Our data illustrate the use of synthetic fruits to better understand the ecology of ant-fruit interactions in variable ecological settings, including human-disturbed landscapes.

Show MeSH