Linking seeds and seedlings: Models and mechanisms.

Plant species differ in many ways, for example their seed sizes, how fast they grow, and their responses to various environmental stresses (drought, being eaten etc). Understanding if and how these different aspects of plant biology are linked is important for understanding why some species occur in specific habitats, and also for predicting the possible effects of environmental change. In most plants and animals larger organisms tend to be slower growing and survive better. This has important consequences when comparing species of different sizes, because we would like to know if the observed differences in, say growth, are simply a consequence of size, or if other aspects of the biology are important. In this research we will use experiments to explore how growth and survival are related to size, so allowing us to determine whether differences between species are simply a consequence of their sizes or not. Using the experimental results we will then be able to determine whether at a common size, fast growing species suffer increased mortality, and how this varies between habitats. This information when combined with mathematical models allow us to predict the best seed size, and so the one we expect species to produce in the field. Currently the understanding of why species produce very different seed sizes is very limited, making this a particularly exciting aspect of the work. All mathematical models make assumptions and so we will produce more general models incorporating realistic aspects of biology, for example larger seedling will be better than small ones when competing for resources, and explore how this alters the predictions of the models.