# Signaling defenses with color: a meta‐analysis of leaf color variation, palatability, and herbivore damage

## TL;DR

This study shows that non-green leaf colors are linked to stronger plant defenses and lower herbivore damage, especially in tropical plants.

## Contribution

The study provides new evidence that leaf color variation influences herbivory through coordinated effects on plant defenses and quality.

## Key findings

- Nongreen leaves are better defended and less nutritious, leading to reduced herbivory and lower herbivore fitness.
- Leaf color effects on herbivory are stronger in tropical plants, while leaf quality is lower in nongreen temperate leaves.
- Both temperate and tropical nongreen leaves show increased plant defenses and reduced insect fitness traits.

## Abstract

We investigated the impact of leaf color variation on herbivory, testing current hypotheses indicating that leaf color could influence herbivory through bottom‐up control (by signaling leaf quality and defenses) or top‐down control (by attracting predators).A comprehensive phylogenetic meta‐analysis was conducted to assess the effects of leaf color on defense traits, leaf palatability, herbivore fitness, and herbivory.We show that nongreen leaves were better defended, less nutritive, and experienced less herbivory, leading to a reduction in herbivore fitness. Stronger effects of leaf color on herbivory were found in tropical plants, whereas lowered leaf quality in nongreen leaves was found in temperate plants. Increased leaf defense and reduction in insect fitness traits were observed in both temperate and tropical nongreen leaves.Our results indicate that leaf color plays a significant role in shaping plant defenses, leaf nutritive value, and herbivore fitness, ultimately modulating levels of herbivory. This suggests coordination between leaf color, defenses, and quality, which may be responsible for patterns of variation in herbivory and fitness‐related traits in herbivores.

We investigated the impact of leaf color variation on herbivory, testing current hypotheses indicating that leaf color could influence herbivory through bottom‐up control (by signaling leaf quality and defenses) or top‐down control (by attracting predators).

A comprehensive phylogenetic meta‐analysis was conducted to assess the effects of leaf color on defense traits, leaf palatability, herbivore fitness, and herbivory.

We show that nongreen leaves were better defended, less nutritive, and experienced less herbivory, leading to a reduction in herbivore fitness. Stronger effects of leaf color on herbivory were found in tropical plants, whereas lowered leaf quality in nongreen leaves was found in temperate plants. Increased leaf defense and reduction in insect fitness traits were observed in both temperate and tropical nongreen leaves.

Our results indicate that leaf color plays a significant role in shaping plant defenses, leaf nutritive value, and herbivore fitness, ultimately modulating levels of herbivory. This suggests coordination between leaf color, defenses, and quality, which may be responsible for patterns of variation in herbivory and fitness‐related traits in herbivores.