Julia Cooke

**The application window for these projects is now closed**

There are two NERC funded PhD studentships advertised with me at The Open University:

Siliceous wood: does silicon matter to plants beyond leaves?

Sexually deceptive orchid pollination strategies: is one true love or broad sex appeal best?

Have a look at the project descriptions in the links or shorter descriptions below, and if you would like any more information or are interested in applying, get in touch here!

Siliceous wood: does silicon matter to plants beyond leaves?

All plants require light, water, air and micronutrients to survive and thrive, but in recent years plant biologists have begun to understand the importance to plants of another element: silicon. Silicon (Si) accumulation in non-woody shoots and leaves is now recognised as an important plant trait, with some species accumulating very little while in others Si comprises up to 10% of their dry mass. The use of Si by leaves as a resource for defence against herbivory, and a strengthening component and to alleviate the impacts of a range of biotic and abiotic stresses is increasingly well understood and appreciated by physiologists and ecologists. There are phylogenetic patterns in shoot/leaf Si accumulation, with some families, such as the Poaceae and Equisetaceae high accumulators. New data suggests that Si is also important in the roots of herbaceous plants as a defence against herbivores.  However, we know almost nothing about the functions of Si accumulation in wood, despite the enormous ecological, practical and commercial importance of this plant tissue. Some recent papers and a few vintage reports suggest there may be substantial variation in wood Si concentration across species, but the significance of this variation is unclear.

A PhD studentship to investigate functions of silicon in wood is available at The Open University through the CENTA programme to work with me (Dr Julia Cooke) and Dr Phil Wheeler.  In this project, a student will:

• Join a dynamic and growing global research community studying plant silicon
• Compile the first broad-scale database of silicon concentrations for wood to undertake the first phylogenetic and comparative trait analyses to determine if wood Si is part of the ‘world-wide wood economics spectrum’
• Learn and use the latest field, laboratory, phylogenetic and statistical analysis skills to explore ecological strategies in plants

We know little about the accumulation or function of silicon in wood. Photo: Thin-section of ring porous woody stem, courtesy Amy Zanne.

Ophrys apifera (left) is pollinated in Europe by a single bee species, which is absent in Britain resulting in solely self-pollination. In contrast, Ophrys insectifera does not self-pollinate but attracts three pollinators from two genera in two insect orders. Photos: Julia Cooke.

Sexually deceptive orchid pollination strategies: is one true love or broad sex appeal best?

Sexually deceptive orchids achieve pollination by mimicking the pheromones and appearance of female insects. The orchids entice males to try to mate with the flowers and pollen is spread through repeated deception among flowers. In this way orchids avoid the costs of producing nectar, but mimicking pheromones and colour is presumably expensive. Sexually deceptive orchid species vary in the number and diversity of pollinator species they attract, ability to self‐pollinate, and if they share pollinators with other species.  It is not known how these different strategies affect pollination success, plant abundance and the population resilience of these often‐vulnerable species. Is it better to mimic one pollinator or several? Is it too expensive to mimic several species perfectly, but imperfect mimicry is enough? And when a pollinator becomes locally extinct, releasing a species from a specific selection pressure, are deceptive traits no longer maintained?

A PhD studentship to research these questions is available at The Open University through the CENTA programme to work with me (Dr Julia Cooke), Dr. Claire Turner and Prof. David Gowing.  In this project, a student will: