Ascidians are a globally distributed group of marine invertebrates which may be solitary or colonial. Colonialism has evolved multiple times in the ascidiacea, along with an associated suite of reproductive characters. Strathmann & Jacobs will investigate the evolution of reproductive strategies by comparing the ecology and development of solitary and colonial ascidians. Their study promises to make several important contributions. First, preliminary data on early growth and survival of solitary and colonial ascidians question basic paradigms of life history strategy, including predicted relationships between egg size, energy content, and offspring fitness. Ascidians are common invasive species worldwide, and the energetics portion of this study will be a timely investigation of potential larval lifespan and hence of dispersal potential. Second, preliminary development data suggest that solitary ascidians, previously thought to be in developmental stasis during dispersal, are capable of an unsuspected degree of differentiation and morphological change while they are competent larvae. This discovery has the potential to change our understanding of how development works in this increasingly important model system and close relative of vertebrates. Finally, this study is one of very few to combine investigations of important developmental transitions with studies of the functional ecological consequences of those changes. This integrative approach could serve as a model for future studies in reproductive ecology and the evolution of development.
