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Published on: November 25, 2016
Coevolution and divergence in the Joshua tree/yucca moth mutualism
William Godsoe1, Jeremy B Yoder, Christopher Irwin Smith
1Department of Biology, University of Idaho, Moscow, Idaho 83844, USA. williamgodsoe@vandals.uidaho.edu
The American Naturalist
|May 9, 2008
Summary
Coevolution between Joshua trees and yucca moths drove the diversification of their floral and moth traits. This study demonstrates that mutualistic coevolution, not environmental factors, shapes species divergence.
Area of Science:
- Ecology
- Evolutionary Biology
- Botany
Background:
- Obligate pollination mutualisms are theorized to drive species diversification through coevolution.
- Disentangling coevolutionary effects from other ecological factors has been challenging.
Purpose of the Study:
- To test if differential selection by two yucca moth species (Tegeticula spp.) caused divergence in two Joshua tree (Yucca brevifolia) varieties.
- To investigate the role of coevolution in the diversification of this plant-pollinator system.
Main Methods:
- Comparative analysis of floral and vegetative trait differentiation between Joshua tree varieties.
- Phylogenetic ancestral state reconstruction to infer the timing of morphological divergence in moths.
Main Results:
- Floral traits involved in pollination evolved faster than vegetative traits.
- A key floral trait showed greater differentiation, mirroring differences in pollinator moth morphology.
- Moth morphological differences emerged after association with Joshua trees.
Conclusions:
- Coevolution, driven by differential selection from yucca moths, is the primary factor shaping divergence in this obligate pollination mutualism.
- Floral and pollinator morphology co-diverged, supporting a strong coevolutionary dynamic.
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