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Tropical forest fragmentation affects floral visitors but not the structure of individual-based palm-pollinator networks.

Dáttilo W, Aguirre A, Quesada M, Dirzo R - PLoS ONE (2015)

Bottom Line: We found that fragment size did not affect the topological structure of the individual-based palm-pollinator network.We also observed that both abundance and variance of effective pollinators of male and female flowers of A. mexicanum increased with forest fragment size.In addition, pollination of A. mexicanum could be more effective in larger fragments, since the greater abundance of pollinators in these fragments may increase the amount of pollen and diversity of pollen donors between flowers of individual plants.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz, Mexico.

ABSTRACT
Despite increasing knowledge about the effects of habitat loss on pollinators in natural landscapes, information is very limited regarding the underlying mechanisms of forest fragmentation affecting plant-pollinator interactions in such landscapes. Here, we used a network approach to describe the effects of forest fragmentation on the patterns of interactions involving the understory dominant palm Astrocaryum mexicanum (Arecaceae) and its floral visitors (including both effective and non-effective pollinators) at the individual level in a Mexican tropical rainforest landscape. Specifically, we asked: (i) Does fragment size affect the structure of individual-based plant-pollinator networks? (ii) Does the core of highly interacting visitor species change along the fragmentation size gradient? (iii) Does forest fragment size influence the abundance of effective pollinators of A. mexicanum? We found that fragment size did not affect the topological structure of the individual-based palm-pollinator network. Furthermore, while the composition of peripheral non-effective pollinators changed depending on fragment size, effective core generalist species of pollinators remained stable. We also observed that both abundance and variance of effective pollinators of male and female flowers of A. mexicanum increased with forest fragment size. These findings indicate that the presence of effective pollinators in the core of all forest fragments could keep the network structure stable along the gradient of forest fragmentation. In addition, pollination of A. mexicanum could be more effective in larger fragments, since the greater abundance of pollinators in these fragments may increase the amount of pollen and diversity of pollen donors between flowers of individual plants. Given the prevalence of fragmentation in tropical ecosystems, our results indicate that the current patterns of land use will have consequences on the underlying mechanisms of pollination in remnant forests.

No MeSH data available.


Related in: MedlinePlus

Individual-based networks involving individuals of Astrocaryum mexicanum (Arecaceae) and their effective (EP) and non-effective (NEP) pollinators in six tropical rainforest fragments (2, 4, 19.4, 34.6, 114.6 and 700 ha respectively) of Los Tuxtlas, southeast Mexico.The right nodes represent different individuals of A. mexicanum considering both (M) male- and (F) female-phase inflorescence. The left nodes correspond to species of floral visitors that interact with plant individuals. Lines indicate interactions between the two trophic levels. Networks were ordered by both number of links and interaction frequencies. Rectangle height is proportional to the number of interactions recorded per species. Different line lengths indicate the frequency of interactions.
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pone.0121275.g002: Individual-based networks involving individuals of Astrocaryum mexicanum (Arecaceae) and their effective (EP) and non-effective (NEP) pollinators in six tropical rainforest fragments (2, 4, 19.4, 34.6, 114.6 and 700 ha respectively) of Los Tuxtlas, southeast Mexico.The right nodes represent different individuals of A. mexicanum considering both (M) male- and (F) female-phase inflorescence. The left nodes correspond to species of floral visitors that interact with plant individuals. Lines indicate interactions between the two trophic levels. Networks were ordered by both number of links and interaction frequencies. Rectangle height is proportional to the number of interactions recorded per species. Different line lengths indicate the frequency of interactions.

Mentions: Across all fragments, we collected a total of 228,772 arthropods (10 orders, 60 species or morphospecies) visiting inflorescences of A. mexicanum individuals (considering both male and female phases) (Fig. 2). Coleoptera was the predominant group (> 50% of the species) including the four main pollinators: Eumystrops centralis, Mystrops mexicanus, Coleopterus aberrans, and Mystrops sp. (Coleoptera), followed by Hymenoptera (20%), while the remaining (30%) was distributed among the other eight orders. The average number of floral visitors per individual of A. mexicanum was 34.83 species (range from: 30 to 42 species). Of the 60 floral visitor species collected, just one to eight species were present in the central core of highly generalist species: E. centralis (Coleoptera), M. mexicanus (Coleoptera), C. aberrans (Coleoptera), Mystrops sp. (Coleoptera), Unidentified sp1 (Diptera), Unidentified sp1 (Coleoptera), Unidentified sp2 (Coleoptera). Male inflorescences had higher numbers of floral visitor species (Mean ± SD: 18.52 ± 1.93 species) when compared with female inflorescences (12.49 ± 0.79 species) (t = −3.8; df = 5; p = 0.01). However, the abundance of pollinators per female inflorescence was higher (530.63 ± 813.04) compared to male inflorescences (425.31 ± 530.63) (t = −2.755; df = 5; p = 0.04).


Tropical forest fragmentation affects floral visitors but not the structure of individual-based palm-pollinator networks.

Dáttilo W, Aguirre A, Quesada M, Dirzo R - PLoS ONE (2015)

Individual-based networks involving individuals of Astrocaryum mexicanum (Arecaceae) and their effective (EP) and non-effective (NEP) pollinators in six tropical rainforest fragments (2, 4, 19.4, 34.6, 114.6 and 700 ha respectively) of Los Tuxtlas, southeast Mexico.The right nodes represent different individuals of A. mexicanum considering both (M) male- and (F) female-phase inflorescence. The left nodes correspond to species of floral visitors that interact with plant individuals. Lines indicate interactions between the two trophic levels. Networks were ordered by both number of links and interaction frequencies. Rectangle height is proportional to the number of interactions recorded per species. Different line lengths indicate the frequency of interactions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380365&req=5

pone.0121275.g002: Individual-based networks involving individuals of Astrocaryum mexicanum (Arecaceae) and their effective (EP) and non-effective (NEP) pollinators in six tropical rainforest fragments (2, 4, 19.4, 34.6, 114.6 and 700 ha respectively) of Los Tuxtlas, southeast Mexico.The right nodes represent different individuals of A. mexicanum considering both (M) male- and (F) female-phase inflorescence. The left nodes correspond to species of floral visitors that interact with plant individuals. Lines indicate interactions between the two trophic levels. Networks were ordered by both number of links and interaction frequencies. Rectangle height is proportional to the number of interactions recorded per species. Different line lengths indicate the frequency of interactions.
Mentions: Across all fragments, we collected a total of 228,772 arthropods (10 orders, 60 species or morphospecies) visiting inflorescences of A. mexicanum individuals (considering both male and female phases) (Fig. 2). Coleoptera was the predominant group (> 50% of the species) including the four main pollinators: Eumystrops centralis, Mystrops mexicanus, Coleopterus aberrans, and Mystrops sp. (Coleoptera), followed by Hymenoptera (20%), while the remaining (30%) was distributed among the other eight orders. The average number of floral visitors per individual of A. mexicanum was 34.83 species (range from: 30 to 42 species). Of the 60 floral visitor species collected, just one to eight species were present in the central core of highly generalist species: E. centralis (Coleoptera), M. mexicanus (Coleoptera), C. aberrans (Coleoptera), Mystrops sp. (Coleoptera), Unidentified sp1 (Diptera), Unidentified sp1 (Coleoptera), Unidentified sp2 (Coleoptera). Male inflorescences had higher numbers of floral visitor species (Mean ± SD: 18.52 ± 1.93 species) when compared with female inflorescences (12.49 ± 0.79 species) (t = −3.8; df = 5; p = 0.01). However, the abundance of pollinators per female inflorescence was higher (530.63 ± 813.04) compared to male inflorescences (425.31 ± 530.63) (t = −2.755; df = 5; p = 0.04).

Bottom Line: We found that fragment size did not affect the topological structure of the individual-based palm-pollinator network.We also observed that both abundance and variance of effective pollinators of male and female flowers of A. mexicanum increased with forest fragment size.In addition, pollination of A. mexicanum could be more effective in larger fragments, since the greater abundance of pollinators in these fragments may increase the amount of pollen and diversity of pollen donors between flowers of individual plants.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz, Mexico.

ABSTRACT
Despite increasing knowledge about the effects of habitat loss on pollinators in natural landscapes, information is very limited regarding the underlying mechanisms of forest fragmentation affecting plant-pollinator interactions in such landscapes. Here, we used a network approach to describe the effects of forest fragmentation on the patterns of interactions involving the understory dominant palm Astrocaryum mexicanum (Arecaceae) and its floral visitors (including both effective and non-effective pollinators) at the individual level in a Mexican tropical rainforest landscape. Specifically, we asked: (i) Does fragment size affect the structure of individual-based plant-pollinator networks? (ii) Does the core of highly interacting visitor species change along the fragmentation size gradient? (iii) Does forest fragment size influence the abundance of effective pollinators of A. mexicanum? We found that fragment size did not affect the topological structure of the individual-based palm-pollinator network. Furthermore, while the composition of peripheral non-effective pollinators changed depending on fragment size, effective core generalist species of pollinators remained stable. We also observed that both abundance and variance of effective pollinators of male and female flowers of A. mexicanum increased with forest fragment size. These findings indicate that the presence of effective pollinators in the core of all forest fragments could keep the network structure stable along the gradient of forest fragmentation. In addition, pollination of A. mexicanum could be more effective in larger fragments, since the greater abundance of pollinators in these fragments may increase the amount of pollen and diversity of pollen donors between flowers of individual plants. Given the prevalence of fragmentation in tropical ecosystems, our results indicate that the current patterns of land use will have consequences on the underlying mechanisms of pollination in remnant forests.

No MeSH data available.


Related in: MedlinePlus