Irreversibility of reproductive versus non-reproductive zooid differentiation in siphonophores

Determine whether the differentiation between reproductive zooids and non-reproductive zooids in siphonophore colonies is irreversible, thereby ascertaining if non-reproductive zooids can ever transition to a reproductive state or contribute to reproductive lineages.

Background

Siphonophores are colonial marine invertebrates composed of clonal zooids that differentiate into reproductive and non-reproductive forms. The growth zone generates batches of zooids that subsequently specialize, with reproductive zooids producing gametes and non-reproductive zooids performing functions such as feeding and defense.

The authors frame this differentiation as an instance of a transmitter–expressor division of labor. However, whether this differentiation is irreversible—i.e., whether non-reproductive zooids can become reproductive or contribute to reproductive lineages—remains unresolved.