“Evolutionary diversification of actomyosin-driven early embryo morphogenesis”

The shape of an animal arises during embryo morphogenesis and involves rotatory movements of
cells relative to eachother. These movements are driven by forces that arise in the actomyosin
cytoskeleton. Biophysical studies in C. elegans have unraveled many of the physcial mechanisms
underlying morphogenetic cell rotations. However, little is known about whether and how these
physical mechanisms diversified. We set out to study this by analyzing actomyosin-driven
morphogenesis in a panel of nematode species that covers more than 100 million years of
evolutionary distance. Although the overall pattern of cell orientations displays little variability in
these nematodes, we find striking differences in the actomyosin behavior. This indicates that
different force-generating mechanisms underlie similar types of morphogenetic cell rotations.
Altogether, these results are indicative of developmental systems drift, where different physical
mechanisms give rise to a similar developmental outcome.