Jack‐of‐all‐trades paradigm meets long‐term data: Generalist herbivores are more widespread and locally less abundant

Abstract

Insect herbivores are relatively specialized. Why this is so is not clear. We examine assumptions about associations between local abundance and dietary specialization using an 18‐year data set of caterpillar–plant interactions in Ecuador. Our data consist of caterpillar–plant associations and include standardized plot‐based samples and general collections of caterpillars, allowing for diet breadth and abundance estimates across spatial scales for 1917 morphospecies. We find that more specialized caterpillars are locally more abundant than generalists, consistent with a key component of the ‘jack of all trades, master of none’ hypothesis. As the diet breadth of species increased, generalists were not as abundant in any one location, but they had broader occupancy across the landscape, which is a pattern that could reflect high plant beta diversity and is consistent with an alternative neutral hypothesis. Our finding that more specialized species can be both rare and common highlights the ecological complexity of specialization.

Extreme drought disrupts plant phenology: Insights from 35 years of cloud forest data in Venezuela

“…For example, seeds of P. tovarense are infested by specialized braconid wasp larvae, Bracon phytophagus Quicke (Flores et al, 2005), which is a very unique life history characteristic for the subfamily Braconinae. Many other obligate, specialized interactions of animals with tropical plants are likely to be abundant locally but not across the tropical landscape, which suggests that small local changes in climate and in resource availability (in this case, flowers and fruits) could drive these animals locally extinct (Sudta et al, 2022).…”

Modern approaches for leveraging biodiversity collections to understand change in plant-insect interactions

“…For example, many specialist pollinators are more susceptible to declines as their more restricted niches provide less redundancy in resource availability (Weiner et al, 2014). It is also likely that the occupancy of specialists across the landscape is low compared to generalists (Sudta et al, 2022) and that more specialized pollinators are less abundant overall (Fort et al, 2016). In either case, there is an expectation of a strong positive correlation between generalization and abundance at some scale, which has conservation implications for threatened specialized plant-pollinator interactions and overall network complexity.…”

Variation in the strength of local and regional determinants of herbivory across the Neotropics

“…Variation in herbivory may increase with scale (spatially and phylogenetically) Prediction: The dispersion and skew of specialist and generalist herbivory will be greater across congeners in a forest as compared to congeners within a local community or members of a subpopulation Regional scale Precipitation seasonality H2. At the regional scale, specialist and generalist herbivory may be higher in seasonal habitats, where leaves may be shorter lived and less well defended (Coley and Barone 1996) Prediction: While specialist and generalist herbivory will be higher in seasonal forests, the pattern may be weaker for specialists as they are more locally abundant across their range (Sudta et al 2022) and are better adapted to higher defenses Average temperature H3. Elevated temperatures may increase herbivore metabolism, developmental rates, population growth, and host plant quality, leading to a positive correlation between temperature and herbivory for both generalists and specialists Prediction.…”