Citation
The Evolution of C4 Photosynthesis
TL;DR
C4 photosynthesis evolved independently 62+ times
Comprehensive review documenting 62+ independent origins of C4 photosynthesis across 19 angiosperm families. C4 is more efficient than C3 photosynthesis in hot, dry environments, explaining its repeated independent evolution.
The extreme frequency of C4 evolution (60+ times) demonstrates how strong selection pressure and constrained solutions guarantee convergence. When a clear fitness advantage exists under specific conditions, evolution discovers it repeatedly.
Key Findings from Sage (2004)
- C4 photosynthesis evolved independently 62+ times
- 19 different angiosperm families evolved C4
- 22-24 independent origins in grasses alone
- Strong selection in hot, dry environments drives repeated convergence