The evolutionary and developmental context of siphonous morphology in Caulerpa taxifolia.

A) Evolutionary relationships among green algae with unicellular, siphonous, siphonocladous, and uninucleate multicellular lifestyles. Diagrams indicate body plan, redrawn from Cocquyt et al. [40]. B) The growing frond apex of Caulerpa taxifolia, producing young pinnules. C) Diagram of sampled regions. D) Principal Component Analysis (PCA) performed on organ RNA-Seq replicates based on transcript accumulation levels. 95% confidence ellipses are indicated for each sampled region. For convenience, a dotted line is provided separating apical from basal pseudo-organ types to relate data back to morphology. Colors indicate different sampled regions (as opposed to nodes in subsequent figures). Red, apex; orange, pinnules; yellow, rachis; green, frond base; blue, stolon; purple, holdfast.