Testing for latitudinal gradients in defense at the macroevolutionary scale

Plant defenses against herbivores are predicted to evolve to be greater in warmer climates, such as lower latitudes where herbivore pressure is also thought to be higher. Instead, recent findings are often inconsistent with this expectation, suggesting alternative hypotheses are needed. We tested fo...

Full description

Saved in:
Bibliographic Details
Published in:Evolution 2018-10, Vol.72 (10), p.2129-2143
Main Authors: Anstett, Daniel N., Ahern, Jeffrey R., Johnson, Marc T. J., Salminen, Juha-Pekka
Format: Article
Language:English
Subjects:
Analytical chemistry
Biogeography
Chemical defense
Climate
evolutionary ecology
Flavonoids
Flowers
Fruits
Herbivores
Latitude
latitudinal gradient
Leaves
LHDH
macroevolution
Metabolites
Multiple regression models
Organic chemistry
ORIGINAL ARTICLE
Phylogeny
Predictions
Pressure
Rainfall
Regression analysis
Resource availability
Secondary metabolites
Species
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Plant defenses against herbivores are predicted to evolve to be greater in warmer climates, such as lower latitudes where herbivore pressure is also thought to be higher. Instead, recent findings are often inconsistent with this expectation, suggesting alternative hypotheses are needed. We tested for latitudinal gradients in plant defense evolution at the macroevolutionary scale by characterizing plant chemical defenses across 80 species of the evening primroses, spanning both North and South America. We quantified phenolics in leaves, flowers, and fruits, using advanced analytical chemistry techniques. Dominant individual ellagitannin compounds, total concentrations of ellagitannins, flavonoids, total phenolics, and compound diversity were quantified. Variation in these compounds was predicted with latitude, temperature, precipitation, and continent using phylogenetic generalized least squares (PGLS) multiple regression models. Latitude did not strongly explain variation in chemical defenses. Instead, fruit total ellagitannins, oenothein A, and total phenolics were greater in species inhabiting regions with colder climates. Using analytical chemistry and 80 species in two continents, we show that contrary to classic predictions, concentrations of secondary metabolites are not greater at lower latitudes or in warmer regions. We propose higher herbivore pressure in colder climates and gradients in resource availability as potential drivers of the observed patterns in Oenothera.
ISSN:0014-3820
1558-5646
DOI:10.1111/evo.13579