Breakdown and delayed cospeciation in the arbuscular mycorrhizal mutualism.
The ancient arbuscular mycorrhizal association between the vast majority of plants and the fungal phylum Glomeromycota is a dominant nutritional mutualism worldwide. In the mycorrhizal mutualism, plants exchange photosynthesized carbohydrates for mineral nutrients acquired by fungi from the soil. This widespread cooperative arrangement is broken by 'cheater' plant species that lack the ability to photosynthesize and thus become dependent upon three-partite linkages (cheater-fungus-photosynthetic plant). Using the first fine-level coevolutionary analysis of mycorrhizas, we show that extreme fidelity towards fungi has led cheater plants to lengthy evolutionary codiversification. Remarkably, the plants' evolutionary history closely mirrors that of their considerably older mycorrhizal fungi. This demonstrates that one of the most diffuse mutualistic networks is vulnerable to the emergence, persistence and speciation of highly specific cheaters.
Merckx
Vincent
V
Laboratory of Plant Systematics, K. U. Leuven, Kasteelpark Arenberg 31, PO Box 2437, 3001 Leuven, Belgium. vincent.merckx@bio.kuleuven.be
Bidartondo
Martin I
MI
D018744:DNA, Plant / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D005658:Fungi / Q000502:physiology; D038821:Mycorrhizae / Q000145:classification* / Q000235:genetics / Q000502:physiology; D010788:Photosynthesis; D010802:Phylogeny; D018517:Plant Roots / Q000145:classification* / Q000235:genetics / Q000502:physiology; D018749:RNA, Plant / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D013045:Species Specificity; D013559:Symbiosis
D018744:DNA, Plant; D004275:DNA, Ribosomal; D018749:RNA, Plant; D012337:RNA, Ribosomal, 18S