Colony formation of Phaeocystis globosa: A case study of evolutionary strategy for competitive adaptation

Some algae possess a multi-morphic life cycle, either in the form of free-living solitary cells or colonies which constantly occur in algal blooms. Though colony formation seems to consume extra energy and materials, many algae tend to outbreak in form of colonies. Here, we hypothesized that colony formation is a selected evolu-tionary strategy to improve population competitiveness and environmental adaptation. To test the hypothesis, different sizes of colonies and solitary cells in a natural bloom of Phaeocystis globosa were investigated. The large colony showed a relatively low oxidant stress level, a nutrient trap effect, and high nutrient use efficiency. The colonial nitrogen and phosphorus concentrations were about 5-10 times higher than solitary cell phycosphere and cellular nutrient allocation decreased with the enlargement of the colonial diameter following the economies of scale law. These features provide the colony with monopolistic competence and could function as an evolu-tionary strategy for competitive adaptation.

Automated summary

Some algae have a multi-morphic life cycle, appearing as either free-living solitary cells or colonies in algal blooms. Despite the extra energy and resources required for colony formation, many algae tend to outbreak in the form of colonies. This study investigated different sizes of colonies and solitary cells in a natural bloom of Phaeocystis globosa and found that colonies have a competitive advantage due to lower oxidant stress, nutrient trap effect, and higher nutrient use efficiency. These features suggest that colony formation is an evolutionary strategy for competitive adaptation.