Comparison of Independent Evolutionary Origins Reveals Both Convergence and Divergence in the Metabolic Mechanisms of Symbiosis.

摘要: Summary Through the merger of previously independent lineages, symbiosis promotes acquisition new traits and exploitation inaccessible ecological niches [ 1 , 2 ], driving evolutionary innovation important ecosystem functions 3 4 5 6 ]. The transient nature establishment makes study symbiotic origins difficult, but experimental comparison could reveal degree convergence in underpinning mechanisms 7 8 We compared metabolic two Paramecium bursaria-Chlorella photosymbiosis 9 10 11 ] using a reciprocal metabolomic pulse-chase method. This showed convergent patterns nutrient exchange utilization for host-derived nitrogen Chlorella genotypes 12 13 symbiont-derived carbon P. bursaria 14 15 Consistent with primary exchange, partner-switched host-symbiont pairings were functional. Direct competition hosts containing native or recombined symbionts against isogenic symbiont-free that fitness benefits increased irradiance varied by genotype. Global metabolism more between than suggested divergent light management. Specifically, algal symbiont either produced photo-protective carotenoid pigments at high chlorophyll, resulting corresponding differences photosynthetic efficiency non-photochemical quenching among pairings. These data suggest multiple P. bursaria-Chlorella use whereas other linked to functioning have diverged. Although enables partner switching diverse strains, phenotypic mismatches from divergence secondary mediate specificity nature.