Abstract
Many plants, including seaweeds, exhibit both a diploid (2n) body (sporophyte) and a haploid (1n) body (gametophyte). These two multicellular phases undergo alternation of generations, a life cycle that entails sexual reproduction in all terrestrial plants and most algal species. The Ulvophyceae are a class of marine green algae (seaweeds) that are primary producers in coastal ecosystems worldwide. The class contains six orders that exhibit sexual reproduction through life cycles that vary among species. Although relationships between life cycle and environment or ecological niche have long been suspected, the mechanisms driving the diversification of ulvophycean life cycles remain poorly understood. Additionally, some ulvophycean life cycles are difficult to distinguish according to conventional definitions. Therefore, in this review, I examine past findings on the diversity and ecological characteristics of ulvophycean life cycles, and propose avenues for future research that will lead to a better evolutionary and ecological understanding of green algal life cycle diversification.
