Juliet Brodie1, Margot Arnould Pétré1,2, Maria Murace3, Rob Mrowicki1 & Silvia Vignolini3
1Science, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK
2 Institut des Substances et Organismes de la Mer, ISOMer, UR 2160, Nantes Université, 44000 Nantes, France
3Yusuf Hamied Department of Chemistry, Lensfield Road, Cambridge, CB2 1EW, UK
The earth is a remarkable place and seaweeds have occupied it for over a third of its existence. Massive upheavals and dramatic changes in climate over the evolutionary history of these remarkable organisms have shaped the seaweeds we see today. Structural colour in seaweeds is a widespread product of that history and we hypothesise that the range of structures evolved are innovations that have enabled species to adapt and survive. We see the physical effect of these structures as striking blue through turquoise to green and pink iridescence. A once neglected subject, our work is demonstrating that this phenomenon is much more widespread than previously reported both geographically and phylogenetically. For example, in the brown algae, structural colour had only been reported in the Dictyotales (oldest group) and Fucales (most recent group), but our recent South Atlantic work has shown that it also occurs in the Desmarestiales and Laminariales. There may be more structures than previously thought or variation in their arrangements, such as in the green algae where microfibrils vary in orientation in different species. We also seem to be seeing more iridescence in the field than in the past. This may reflect greater awareness or range expansion of species with structural colour into new geographical areas but it also raises questions as to whether structures can be mobilised, created or acquired in response to climate change. This talk will explore these ideas through new observations and geological and contemporary hypotheses.