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Summary Polyploidy is a key driver of ecological and evolutionary processes in plants, yet little is known about its effects on biotic interactions. This gap in knowledge is especially profound for nutrient acquisition mutualisms, despite the fact that they regulate global nutrient cycles and structure ecosystems. Generalism in mutualistic interactions depends on the range of potential partners (niche breadth), the benefits obtained and ability to maintain benefits across a variety of partners (fitness plasticity). Here, we determine how each of these is influenced by polyploidy in the legume–rhizobium mutualism.We inoculated a broad geographic sample of natural diploid and autotetraploid alfalfa (Medicago sativa) lineages with a diverse panel ofSinorhizobiumbacterial symbionts. To analyze the extent and mechanism of generalism, we measured host growth benefits and functional traits.Autotetraploid plants obtained greater fitness enhancement from mutualistic interactions and were better able to maintain this across diverse rhizobial partners (i.e. low plasticity in fitness) relative to diploids. These benefits were not attributed to increases in niche breadth, but instead reflect increased rewards from investment in the mutualism.Polyploid plants displayed greater generalization in bacterial mutualisms relative to diploids, illustrating another axis of advantage for polyploids over diploids.
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Mutualistic networks emerging from adaptive niche-based interactions
Abstract Mutualistic networks are vital ecological and social systems shaped by adaptation and evolution. They involve bipartite cooperation via the exchange of goods or services between actors of different types. Empirical observations of mutualistic networks across genres and geographic conditions reveal correlated nested and modular patterns. Yet, the underlying mechanism for the network assembly remains unclear. We propose a niche-based adaptive mechanism where both nestedness and modularity emerge simultaneously as complementary facets of an optimal niche structure. Key dynamical properties are revealed at different timescales. Foremost, mutualism can either enhance or reduce the network stability, depending on competition intensity. Moreover, structural adaptations are asymmetric, exhibiting strong hysteresis in response to environmental change. Finally, at the evolutionary timescale we show that the adaptive mechanism plays a crucial role in preserving the distinctive patterns of mutualism under species invasions and extinctions.
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- Award ID(s):
- 1817124
- PAR ID:
- 10199723
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 11
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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