Abstract
The actin cytoskeleton governs a vast array of core eukaryotic phenotypes that include cell movement, endocytosis, vesicular trafficking, and cytokinesis. Although the basic principle underlying these processes is strikingly simple - actin monomers polymerize into filaments that can depolymerize back into monomers - eukaryotic cells have sophisticated and layered control systems to regulate actin dynamics. The evolutionary origin of these complex systems is an area of active research. Here, we review the regulation and diversity of actin networks to provide a conceptual framework for cell biologists interested in evolution and for evolutionary biologists interested in actin-dependent phenotypes.