The top-down and indirect effects of insects on plant communities depend on patterns of host use, which are often poorly documented, particularly in species-rich tropical forests. At Barro Colorado Island, Panama, we compiled the first food web quantifying trophic interactions between the majority of co-occurring woody plant species and their internally feeding insect seed predators. Our study is based on more than 200 000 fruits representing 478 plant species, associated with 369 insect species. Insect host-specificity was remarkably high: only 20% of seed predator species were associated with more than one plant species, while each tree species experienced seed predation from a median of two insect species. Phylogeny, but not plant traits, explained patterns of seed predator attack. These data suggest that seed predators are unlikely to mediate indirect interactions such as apparent competition between plant species, but are consistent with their proposed contribution to maintaining plant diversity via the Janzen-Connell mechanism.

• MeSH
• biodiverzita MeSH
• fylogeneze MeSH
• hmyz * MeSH
• lesy * MeSH
• potravní řetězec * MeSH
• semena rostlinná MeSH
• tropické klima * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• dopisy MeSH
• Geografické názvy
• Panama MeSH

Understanding variation in resource specialization is important for progress on issues that include coevolution, community assembly, ecosystem processes, and the latitudinal gradient of species richness. Herbivorous insects are useful models for studying resource specialization, and the interaction between plants and herbivorous insects is one of the most common and consequential ecological associations on the planet. However, uncertainty persists regarding fundamental features of herbivore diet breadth, including its relationship to latitude and plant species richness. Here, we use a global dataset to investigate host range for over 7,500 insect herbivore species covering a wide taxonomic breadth and interacting with more than 2,000 species of plants in 165 families. We ask whether relatively specialized and generalized herbivores represent a dichotomy rather than a continuum from few to many host families and species attacked and whether diet breadth changes with increasing plant species richness toward the tropics. Across geographic regions and taxonomic subsets of the data, we find that the distribution of diet breadth is fit well by a discrete, truncated Pareto power law characterized by the predominance of specialized herbivores and a long, thin tail of more generalized species. Both the taxonomic and phylogenetic distributions of diet breadth shift globally with latitude, consistent with a higher frequency of specialized insects in tropical regions. We also find that more diverse lineages of plants support assemblages of relatively more specialized herbivores and that the global distribution of plant diversity contributes to but does not fully explain the latitudinal gradient in insect herbivore specialization.

• MeSH
• biodiverzita MeSH
• biologické modely MeSH
• býložravci fyziologie   MeSH
• dieta * MeSH
• ekosystém MeSH
• fylogeneze MeSH
• hmyz klasifikace   fyziologie   MeSH
• hostitelská specificita MeSH
• Lepidoptera klasifikace   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Classical niche theory explains the coexistence of species through their exploitation of different resources. Assemblages of herbivores coexisting on a particular plant species are thus expected to be dominated by species from host-specific guilds with narrow, coexistence-facilitating niches rather than by species from generalist guilds. Exactly the opposite pattern is observed for folivores feeding on trees in New Guinea. The least specialized mobile chewers were the most species rich, followed by the moderately specialized semiconcealed and exposed chewers. The highly specialized miners and mesophyll suckers were the least species-rich guilds. The Poisson distribution of herbivore species richness among plant species in specialized guilds and the absence of a negative correlation between species richness in different guilds on the same plant species suggest that these guilds are not saturated with species. We show that herbivore assemblages are enriched with generalists because these are more completely sampled from regional species pools. Herbivore diversity increases as a power function of plant diversity, and the rate of increase is inversely related to host specificity. The relative species diversity among guilds is thus scale dependent, as the importance of specialized guilds increases with plant diversity. Specialized insect guilds may therefore comprise a larger component of overall diversity in the tropics (where they are also poorly known taxonomically) than in the temperate zone, which has lower plant diversity.

• MeSH
• biodiverzita MeSH
• biologická adaptace fyziologie   MeSH
• biologické modely MeSH
• druhová specificita MeSH
• hmyz fyziologie   MeSH
• interakce hostitele a parazita MeSH
• potravní řetězec MeSH
• stromy parazitologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Geografické názvy
• Nová Guinea MeSH

1. The extent to which plant-herbivore feeding interactions are specialized is key to understand the processes maintaining the diversity of both tropical forest plants and their insect herbivores. However, studies documenting the full complexity of tropical plant-herbivore food webs are lacking. 2. We describe a complex, species-rich plant-herbivore food web for lowland rain forest in Papua New Guinea, resolving 6818 feeding links between 224 plant species and 1490 herbivore species drawn from 11 distinct feeding guilds. By standardizing sampling intensity and the phylogenetic diversity of focal plants, we are able to make the first rigorous and unbiased comparisons of specificity patterns across feeding guilds. 3. Specificity was highly variable among guilds, spanning almost the full range of theoretically possible values from extreme trophic generalization to monophagy. 4. We identify guilds of herbivores that are most likely to influence the composition of tropical forest vegetation through density-dependent herbivory or apparent competition. 5. We calculate that 251 herbivore species (48 of them unique) are associated with each rain forest tree species in our study site so that the ∼200 tree species coexisting in the lowland rain forest community are involved in ∼50,000 trophic interactions with ∼9600 herbivore species of insects. This is the first estimate of total herbivore and interaction number in a rain forest plant-herbivore food web. 6. A comprehensive classification of insect herbivores into 24 guilds is proposed, providing a framework for comparative analyses across ecosystems and geographical regions.

• MeSH
• biodiverzita MeSH
• hmyz klasifikace   fyziologie   MeSH
• potravní řetězec MeSH
• rostliny klasifikace   MeSH
• stravovací zvyklosti fyziologie   MeSH
• stromy MeSH
• tropické klima MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Geografické názvy
• Papua Nová Guinea MeSH