Record ID No. |
6548 |
Author(s) |
Kiers E. T.* and van der Heijden M. G. A.** , 2006 |
Affiliation |
*Institute of Ecological Sciences, Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, The Netherlands; **2Organismic and Evolutionary Biology, University of Massachusetts, Amherst, Massachusetts 01003-5810. |
Title |
Mutualistic Stability in the Arbuscular Mycorrhizal Symbiosis: Exploring Hypotheses of Evolutionary Cooperation. |
Source. Vol.(no):Page |
Ecology. 87(7): 1627-1636. |
Categories |
Mycorrhiza General |
Subjects |
Biological Interaction Ecology |
Host |
NA |
Organism |
NA |
Country |
The Netherlands |
Abstracts |
The 450-million-year-old symbiosis between the majority of land plants and
arbuscular mycorrhizal fungi (AMF) is one of the most ancient, abundant, and ecologically important mutualisms on Earth. Yet, the evolutionary stability of mycorrhizal associations is still poorly understood, as it follows none of the constraints thought to stabilize cooperation in other well-known mutualisms. The capacity of both host and symbiont to simultaneously interact with several partners introduces a unique dilemma; detecting and punishing those
exploiting the mutualism becomes increasingly difficult if these individuals can continue to access resources from alternative sources. Here, we explore four hypotheses to explain
evolutionary cooperation in the arbuscular mycorrhizal symbiosis: (1) pseudo-vertical transmission and spatial structuring of plant and fungal populations leading to local adaptation of partners; (2) luxury resource exchange in which plants trade surplus carbon for
excess fungal nutrients; (3) partner choice allowing partners to associate with better cooperators; and (4) host and symbiont sanctions which actively reward good partners and punish less cooperative ones. We propose that mycorrhizal cooperation is promoted by an exchange of surplus resources between partners and enforced through sanctions by one or
both partners. These mechanisms may allow plant and fungal genotypes to discriminate
against individuals employing exploitative strategies, promoting patterns of partner choice. Together these selection pressures provide a framework for understanding the stabilization of mycorrhizal cooperation over evolutionary time. |