Topological change of Andean plant–pollinator networks along an altitudinal gradient

Ramos‐Jiliberto, Rodrigo; Domínguez, Daniela; Espinoza, Claudia; López, G Dorotea; Valdovinos, Fernanda S.; Bustamante, Ramiro O.; Medel, Rodrigo

doi:10.1016/j.ecocom.2009.06.001

Cited by 85 publications

(80 citation statements)

References 28 publications

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“…For example, Olesen and Jordano (2002) found that plant-pollinator networks in lowlands and at high latitudes show high connectance (i.e., a high fraction of potential interactions actually realized in the field). Likewise, Ramos-Jiliberto et al (2010) found that nestedness (i.e., the tendency for a network to show little reciprocal specialization) systematically decrease in pollination networks at higher altitudes, while Albrecht et al (2010) found higher nestedness in glacier forelands than in late successional communities.…”

Section: Electronic Supplementary Materialsmentioning

confidence: 94%

Interaction type influences ecological network structure more than local abiotic conditions: evidence from endophytic and endolichenic fungi at a continental scale

et al. 2015

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Understanding the factors that shape community assembly remains one of the most enduring and important questions in modern ecology. Network theory can reveal rules of community assembly within and across study systems and suggest novel hypotheses regarding the formation and stability of communities. However, such studies generally face the challenge of disentangling the relative influence of factors such as interaction type and environmental conditions on shaping communities and associated networks. Endophytic and endolichenic symbioses, characterized by microbial species that occur within healthy plants and lichen thalli, represent some of the most ubiquitous interactions in nature. Fungi that engage in these symbioses are hyperdiverse, often horizontally transmitted, and functionally beneficial in many cases, and they represent the diversification of multiple phylogenetic groups. We evaluated six measures of ecological network structure for >4100 isolates of endophytic and endolichenic fungi collected systematically from five sites across North America. Our comparison of these co-occurring interactions in biomes ranging from tundra to subtropical forest showed that the type of interactions (i.e., endophytic vs. endolichenic) had a much more pronounced influence on network structure than did environmental conditions. In particular, endophytic networks were less nested, less connected, and more modular than endolichenic networks in all sites. The consistency of the network structure within each interaction type, independent of site, is encouraging for current efforts devoted to gathering metadata on ecological network structure at a global scale. We discuss several mechanisms potentially responsible for such patterns and draw attention to knowledge gaps in our understanding of networks for diverse interaction types.

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Section: Electronic Supplementary Materialsmentioning

confidence: 94%

Interaction type influences ecological network structure more than local abiotic conditions: evidence from endophytic and endolichenic fungi at a continental scale

et al. 2015

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“…Our results are similar to those found for binary plant–pollinator networks along a single elevational gradient in the Chilean Andes, where fewer interactions per species were observed with increasing elevation (Ramos‐Jiliberto et al . ), suggesting that environmental filtering at high elevations may act upon both mutualistic and antagonistic networks.…”

Section: Discussionmentioning

confidence: 99%

“…Networks of mutualistic plant–pollinator interactions have been examined along elevational gradients (Devoto, Medan & Montaldo ; Ramos‐Jiliberto et al . ; Benadi et al . ).…”

Section: Introductionmentioning

confidence: 99%

Changes in host–parasitoid food web structure with elevation

Maunsell

Kitching

Burwell

et al. 2014

Journal of Animal Ecology

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Summary1. Gradients in elevation are increasingly used to investigate how species respond to changes in local climatic conditions. Whilst many studies have shown elevational patterns in species richness and turnover, little is known about how food web structure is affected by elevation. 2. Contrasting responses of predator and prey species to elevation may lead to changes in food web structure. We investigated how the quantitative structure of a herbivore-parasitoid food web changes with elevation in an Australian subtropical rain forest. 3. On four occasions, spread over 1 year, we hand-collected leaf miners at twelve sites, along three elevational gradients (between 493 m and 1159 m a.s.l). A total of 5030 insects, including 603 parasitoids, were reared, and summary food webs were created for each site. We also carried out a replicated manipulative experiment by translocating an abundant leaf-mining weevil Platynotocis sp., which largely escaped parasitism at high elevations (≥900 m a.s.l.), to lower, warmer elevations, to test if it would experience higher parasitism pressure. 4. We found strong evidence that the environmental change that occurs with increasing elevation affects food web structure. Quantitative measures of generality, vulnerability and interaction evenness decreased significantly with increasing elevation (and decreasing temperature), whilst elevation did not have a significant effect on connectance. Mined plant composition also had a significant effect on generality and vulnerability, but not on interaction evenness. Several relatively abundant species of leaf miner appeared to escape parasitism at higher elevations, but contrary to our prediction, Platynotocis sp. did not experience greater levels of parasitism when translocated to lower elevations. 5. Our study indicates that leaf-mining herbivores and their parasitoids respond differently to environmental conditions imposed by elevation, thus producing structural changes in their food webs. Increasing temperatures and changes in vegetation communities that are likely to result from climate change may have a restructuring effect on host-parasitoid food webs. Our translocation experiment, however, indicated that leaf miners currently escaping parasitism at high elevations may not automatically experience higher parasitism under warmer conditions and future changes in food web structure may depend on the ability of parasitoids to adapt to novel hosts.

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“…This is actually consistent with physiology‐based theories, such as those proposed to explain Bergmann's rule (Classen et al, ). Still, the association between body size and resource use, dispersal capacity and pollination efficiency (Chown & Gaston, ) might also explain the positive relationship between elevation and insect body size at the community scale, especially when trophic resources decrease with elevation (Miller‐Struttmann & Galen, ; Ramos‐Jiliberto et al, ). Pollinator body‐size is highly positively correlated with foraging distance and proboscis length in many taxa (Agosta & Janzen, ; Byrne, Buchmann, & Spangler, ; Casey, May, & Morgan, ; Greenleaf, Williams, Winfree, & Kremen, ; Levy & Nufio, ).…”

Section: Introductionmentioning

confidence: 99%

Beta diversity and specialization in plant–pollinator networks along an elevational gradient

Lara‐Romero

Seguí

Pérez‐Delgado

et al. 2019

Journal of Biogeography

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Aim To assess whether the reduced nutritional resources available for pollinators due to plant community simplification along an elevational plant‐diversity gradient changes pollinator niche breadth and richness. Additionally, we evaluated how body size and proboscis length of pollinators shifted along the gradient, and whether these changes were related to pollinator niche breadth. Location An elevational gradient (2,350–3,520 m a.s.l.) on the oceanic high‐mountain strato‐volcano of El Teide (Tenerife, Canary Islands). Taxon Flowering plant and pollinator species. Methods We compared quantitative plant–pollinator networks along the plant‐diversity gradient. We calculated a set of niche‐based topological metrics that capture the degree of specialization, niche breadth and niche overlap. Furthermore, we obtained β‐diversity measures and the proportion of replacement and richness components. Results There was an overall decline in species richness of pollinators with increasing elevation. This decline was mainly driven by the loss of species along the elevational gradient, which conformed a nested subset pattern. The whole network showed less specialization, greater connectance and lower modularity towards the summit. At high elevations, pollinators were more generalized and less selective in their flower choice, showing a greater trophic niche breadth compared to pollinators at lower elevations. Mean body size of pollinators increased with elevation, and species body size and proboscis length were positively associated with the number of plant species visited. Main conclusions Overall, results indicated that the elevational gradient filters pollinator species, probably according to their thermal tolerance and ability to exploit a wide range of trophic resources. The finding that pollinators become more generalized and opportunistic at higher elevations is a novel result, which may have implications for new research into how ecological networks vary over environmental gradients. From an applied perspective, our results highlight the importance of considering the spatial variation of species assemblages when aiming to construct functionally reliable interaction networks along environmental gradients.

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Topological change of Andean plant–pollinator networks along an altitudinal gradient

Cited by 85 publications

References 28 publications

Interaction type influences ecological network structure more than local abiotic conditions: evidence from endophytic and endolichenic fungi at a continental scale

Interaction type influences ecological network structure more than local abiotic conditions: evidence from endophytic and endolichenic fungi at a continental scale

Changes in host–parasitoid food web structure with elevation

Beta diversity and specialization in plant–pollinator networks along an elevational gradient

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