During tissue development, progenitors differentiate into multiple cell types in a manner that is reproducible and robust to some sources of variation. Over evolutionary time, new cellular phenotypes arise. What features of development make it simultaneously evolvable and robust? This question has been asked of body-plans but it can be considered for cell differentation-dynamics. We have explored developmental plasticity in differentiation by (1) aligning single cell RNA sequencing trajectories of vertebrate erythropoiesis, (2) examining natural variation in human hematopoiesis, and (3) examining variation in the blood of several species of our nearest invertebrate relatives — the tunicates. Within vertebrate erythropoiesis, there is some evidence that terminal differentiation is more variable than earlier stages of fate specification. This work will introduce a new computational tool — BAGEL — a lightweight algorithm for cross-species alignment of gene expression dynamics across single-cell datasets, and microfluidic technology that expands our ability to carry out functional genomic analysis on clones, using semi-permeable micro-capsules.