What causes size coupling in fruit–frugivore interaction webs?

Burns, Kevin C.

doi:10.1890/12-1161.1

Cited by 81 publications

(89 citation statements)

References 31 publications

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“…Conversely, bird gapes are normally much smaller than mammals' mouths, thus reducing the range of fruit sizes birds can eat, and creating a size threshold in their interaction patterns (Githiru, Lens, Bennur, & Ogol, ). Our results agree with those of Burns () on a bird–frugivore assemblage in New Zealand showing that, in general, birds not only present a size‐constrained relationship, but also seem to randomly consume the fruits that are smaller than their gape size. In addition, Wheelwright () clearly catalogued the morphological constraints when he found many large fruits scarred by bill marks below fruiting trees (where survival prospects are low).…”

Section: Discussionsupporting

confidence: 91%

“…There is an ongoing discussion regarding the prevalence of passive vs. behavioral interaction rules in determining mutualistic interaction patterns, with some studies supporting preferential foraging (Moermond & Denslow, ; Tewksbury & Nabhan, ), and others supporting random and interchangeable interaction patterns only limited by trait‐based constraints (Burns, , ; Zamora, ). However, most of these studies focus only on bird species.…”

Section: Discussionmentioning

confidence: 99%

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Species traits and interaction rules shape a species‐rich seed‐dispersal interaction network

Sebastián‐González

Pires

Donatti

et al. 2017

Ecology and Evolution

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Species phenotypic traits affect the interaction patterns and the organization of seed‐dispersal interaction networks. Understanding the relationship between species characteristics and network structure help us understand the assembly of natural communities and how communities function. Here, we examine how species traits may affect the rules leading to patterns of interaction among plants and fruit‐eating vertebrates. We study a species‐rich seed‐dispersal system using a model selection approach to examine whether the rules underlying network structure are driven by constraints in fruit resource exploitation, by preferential consumption of fruits by the frugivores, or by a combination of both. We performed analyses for the whole system and for bird and mammal assemblages separately, and identified the animal and plant characteristics shaping interaction rules. The structure of the analyzed interaction network was better explained by constraints in resource exploitation in the case of birds and by preferential consumption of fruits with specific traits for mammals. These contrasting results when looking at bird–plant and mammal–plant interactions suggest that the same type of interaction is organized by different processes depending on the assemblage we focus on. Size‐related restrictions of the interacting species (both for mammals and birds) were the most important factors driving the interaction rules. Our results suggest that the structure of seed‐dispersal interaction networks can be explained using species traits and interaction rules related to simple ecological mechanisms.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Species traits and interaction rules shape a species‐rich seed‐dispersal interaction network

Sebastián‐González

Pires

Donatti

et al. 2017

Ecology and Evolution

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“…I predicted body size to be an important variable explaining dispersers' role in the network structure. Large birds are expected to be able to consume fruits with larger sizes (Wheelwright ; Burns ) and size correlates with the number of interacting partners in ant–plant and in plant–hummingbird mutualistic interactions (Chamberlain & Holland ; Dalsgaard et al . ).…”

Section: Discussionmentioning

confidence: 99%

Drivers of species' role in avian seed‐dispersal mutualistic networks

Sebastián‐González¹

2017

Journal of Animal Ecology

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The mutualistic interaction between frugivore birds and the fruiting plants they disperse presents an asymmetric interaction pattern, with some species having a more important role (i.e. being essential) for maintaining the structure and functioning of the interaction network. The identification of the biological characteristics of these species is of major importance for the understanding and conservation of seed-dispersal interactions. In this study, I use a network approach and avian seed-dispersal networks from 23 different geographical areas to test five hypotheses about species characteristics determining the structure of the assemblage. I expected (i) large birds to forage on a large number of fruits and (ii) large fruits to be dispersed by few bird species (because of morphological constraints), and (iii) highly energetic fruits to be dispersed by more bird species (in accordance with optimal foraging theory). Besides the number of interacting partners, I also expected (iv) large birds and (v) small energetic fruits to be important for the maintenance of the structure of the interactions in seed-dispersal networks. As species that are closely related are more likely to be similar to each other, I performed phylogenetically corrected analyses to account for this data dependence. Although bird size was not associated to species important in the maintenance of the structure of the seed-dispersal community, I identified that bird species whose diet was strongly dependent on fruits were important for the structure of the network. Regarding the plants, I found that large fruits were dispersed by fewer species, but the most important attribute to predict the role of a fruit was its energy content (higher energy, more bird species dispersing the plant, but low-energy fruits being of conservation concern because they are dispersed by specific species). The results of this study suggest that the role of the species in seed-dispersal assemblages seems to be determined by the role of the species as consumers (frugivory degree for animals) or by their nutritional inputs (energy content for fruits) rather than by morphological constrains.

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“…Our study is the first to show the negative lower boundary of the relationship between animal body mass and ingested seed size. Most previous studies had much smaller sample sizes than the present one, and so may have lacked the statistical power to distinguish between flat and negative lower boundaries (Wheelwright, ; Debussche & Isenmann, ; Bollen et al ., ; Burns, ). In addition, because large animals are rare in communities, and less dependent on fruits (Vidal et al ., ), previous quantifications of the relationship between animal body mass and ingested seed size focused on small‐ and medium‐sized frugivores (but see Gautier‐Hion et al ., ), thus missing the very large herbivores that drive the negative slope of the 5th quantile we observed.…”

Section: Discussionmentioning

confidence: 99%

“…Despite the widespread awareness of the importance of body size in a variety of networks (Woodward et al ., ), the relationship between seed size and animal body size has not been quantified across the full suite of potential seed dispersers. Most previous studies of the relationship between body mass and ingested seed size have focused on avian frugivores (Wheelwright, ; Cath & Catterall, ; Burns, ). In this paper, we provide a comprehensive quantification of the relationships between animal body mass and ingested seed size across all vertebrate groups, including fish, amphibians, reptiles, birds and mammals.…”

Section: Introductionmentioning

confidence: 97%

A mammoth mouthful? A test of the idea that larger animals ingest larger seeds

Chen

Moles

2015

Global Ecology and Biogeography

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Aim It has been widely assumed that large seeds generally require large animals to ingest and disperse them. However, this relationship has only been quantified in single animal groups (e.g. birds) and in a few communities. Our goal was to provide the first broad-scale study of the relationship between animal body mass and ingested seed size.Location Global. MethodsWe compiled a dataset of 13,135 unique animal × seed interactions, animal body masses and seed sizes in these interactions, across all vertebrate groups (fish, amphibians, reptiles, birds and mammals). ResultsContrary to expectations, ingested seed size was negatively related to animal body mass. This negative relationship was largely driven by large ungulates ingesting small and dry seeds, and analyses excluding either ungulates or seeds with non-fleshy fruit types showed a positive relationship between animal body mass and ingested seed size. Large animals ingested both seeds with a larger maximum size (the 95th quantile had a positive slope) and a smaller minimum size (the 5th quantile had a negative slope). Larger animals ingest larger seeds from fleshy fruits but smaller seeds from non-fleshy fruits. A significant positive relationship was found between animal size and the number of seed species ingested. Main conclusionsOur data show that one of the assumptions that has underpinned the study of animal-seed interactions does not hold true across the full range of animal taxa and fruit types. These findings shed new light on theories about which types of plant species might be at risk if large animals go extinct, and cast doubt on the generality of a few theories (e.g. optimal diet theory, fruit-size hypothesis) about the relationship between frugivores and seeds.

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What causes size coupling in fruit–frugivore interaction webs?

Cited by 81 publications

References 31 publications

Species traits and interaction rules shape a species‐rich seed‐dispersal interaction network

Species traits and interaction rules shape a species‐rich seed‐dispersal interaction network

Drivers of species' role in avian seed‐dispersal mutualistic networks

A mammoth mouthful? A test of the idea that larger animals ingest larger seeds

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