Biology subjects

Wetzel, W. C.

Publications and source records attributed to Wetzel, W. C..

3 recordsLinked to original sources

bioRxiv2026

Nonlinear Impacts of Herbivory on Plants Explain the Herbivory Paradox

Herbivores strongly shape plant ecology and evolution. Yet plants typically sustain low, tolerable levels of damage, raising the question of how herbivory influences plant biology despite often weak fitness effects. Analyzing 1,145 datasets of the effects of damage on fitness for 103 plant species worldwide, we show that nonlinear tolerance to damage is one explanation for this paradoxical contradiction. Plants are tolerant of low levels of damage, but infrequent, severe damage levels disproportionately reduce plant fitness. Models incorporating nonlinear tolerance suggest that disproportionate tolerance to low levels of damage stabilizes population dynamics and promotes coevolutionary feedback with herbivores. Pervasive nonlinear tolerance shows consistent patterns across environmental gradients, may alter the stability of food webs, and may explain why herbivory matters despite the world being green.

ecology↗

bioRxiv2024

Global test of the enemy release hypothesis reveals similar patterns of herbivory across native and non-native plants

The Enemy Release Hypothesis (ERH) proposes that non-native plants escape their co-evolved herbivores and benefit from reduced herbivory in their introduced ranges. Numerous studies have tested this hypothesis, with conflicting results, but previous studies focus on average levels of herbivory and overlook the substantial within-population variability in herbivory, which may provide unique insights into the ERH. We tested differences in mean herbivory and added a novel approach to the ERH by comparing within-population variability in herbivory between native and non-native plant populations. We include several covariates that might mask an effect of enemy release, including latitude, regional plant richness, plant growth form and plant cover. We use leaf herbivory data collected by the Herbivory Variability Network for 788 plant populations (616 native range populations and 172 introduced range populations) of 503 different native and non-native species distributed worldwide. We found no overall differences in mean herbivory or herbivory variability between native and non-native plant populations. Taken together, our results indicate no evidence of enemy release for non-native plants, suggesting that enemy release is not a generalized mechanism favoring the success of non-native species. OPEN RESEARCH STATEMENTData published and available for peer review at https://doi.org/10.5061/dryad.44j0zpckm

ecology↗

bioRxiv2020

Domestication has altered within-plant trait variability in a crop plant

O_LIFor 10,000 years humans have altered plant traits through domestication and ongoing crop improvement, shaping plant form and function in agroecosystems. To date, studies have focused on how these processes have shaped whole-plant or average traits; however, plants also have characteristic levels of trait variability among their repeated parts, which can be heritable and mediate critical ecological interactions. As concerns about sustainable pest management increase, there is growing interest in approaches that increase trait diversity in crop agroecosystems. Here, we examine an under-appreciated scale of trait variation - among leaves, within plants - that may have changed through the process of domestication and improvement in a key crop. C_LIO_LIWe explore how levels of within-plant, among-leaf trait variability differ between cultivars and wild relatives of alfalfa (Medicago sativa), a key forage crop with an 8,000 year cultivation history. We grew individual plants from 30 wild populations and 30 cultivars, encompassing a range of domestication and improvement histories. For each plant, we quantify variability in a broad suite of physical, nutritive, and chemical leaf traits, including measures of chemical dissimilarity (beta diversity) among leaves. C_LIO_LIWe find that intra-individual trait variability has changed over the course of domestication and crop improvement, with effects often larger than changes in trait means. Cultivated alfalfa had elevated variability in SLA, trichomes, and C:N; increased diversity in defensive compounds; and reduced variability in phytochemical composition. We also elucidate fundamental associations between trait means and overall investment in secondary metabolites with patterns of among-leaf variability and chemical diversity. C_LIO_LIWe conclude that within-plant variability is an overlooked dimension of trait diversity in this globally critical agricultural crop. We find that trait variability is actually higher in cultivated plants compared to wild progenitors for multiple nutritive, physical, and chemical traits, highlighting a scale of variation that may mitigate loss of trait diversity at other scales in alfalfa agroecosystems and in other crops with similar domestication and improvement histories. C_LI

evolutionary biology↗