Figure 2.

Cladogram of ycf1 Evolution.

ycf1 was gained in the green lineage (event A), leading to the initial distribution of the ancestral chlorophyte-type (Cte)-YCF1 among all Chloroplastida (yellow trajectory). Within the charophytes, the ancestral “800 amino acid” Cte-YCF1 was transformed into the “1500 amino acid” Streptophyte-type (Ste)-YCF1 (event B), leading to its distribution among Embryophyta and their closest charophyte neighbors (orange trajectory). The vast majority of the embryophytes (“all” others) retained the Ste-YCF1, while it was lost in the Poaceae (event C) and a few other cases mentioned throughout the text. Note that in some chlorophyte algae, the ancestral Cte-YCF1 (initially 800 amino acids in length) also experienced some sequence duplication events that led to much longer versions of YCF1. However, this occurred independently from event B.