Abstract
The assumption that traits have associated costs as well as benefits is essential to the understanding of the evolution of defences against consumers. However, for seaweeds, direct evidence for a cost of chemical defence is lacking. Moreover, theory is largely derived from terrestrial literature, which may be inappropriate for algae, given that much of this theory is linked to the biology of plants. Marine algae do not have roots, translocation is unusual, and, the entire thallus is capable of photosynthesis and nutrient absorption. These and other differences are likely to affect the cost of chemical defence and a new theoretical perspective is needed for algae. Without a conceptual understanding of algae function it will be difficult to recognize and predict the effects of environmental change on algal communities and associated species. This study will test the general hypothesis that chemical defences are costly for macroalgae, and, investigate the role of growth, plant size, and environmental conditions in determining costs. Two species of red algae will be used as test species. The questions will be addressed through a combined empirical and modelling approach and from this we aim to develop a new theoretical framework of chemical defence that is based explicitly on the biology of seaweeds. From a more general perspective, this is integral if we are to understand the responses of marine algae to environmental changes that affect algal growth and reproduction.
Sweden