1. Department of Ecology and Evolutionary BiologyUniversity of Toronto Toronto Ontario M5S 3G5 Canada
2. Current Address: Department of Vertebrate Zoology, National Museum of Natural HistorySmithsonian Institution 10th and Constitution Ave NW Washington DC 20560‐0162
3. Department of Cell and Systems BiologyUniversity of Toronto Toronto Ontario M5S 3G5 Canada
4. Current Address: UCL Institute of Ophthalmology 11–43 Bath Street London EC1V 9EL United Kingdom
5. Centre for the Analysis of Genome Evolution and FunctionUniversity of Toronto Toronto Ontario M5S 3B2 Canada