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I am currently reading for a PhD in the Committee on Evolutionary Biology (CEB http://evbio.uchicago.edu/about/) at the University of Chicago. My biological interests are broad, but coalesce around the following themes: evolution, phylogeny, biogeography and endemism. My current research examines whether the ancestral primate was night active or day active. I use DNA extracted in the Museum's Pritzker Lab from frozen tissues housed in the Museum's zoology collections to collect my data. My long association with the Field Museum, began as a volunteer in the Botany Collections in late 1999.
Bsc Hons, University of KwaZulu Natal (UKZN), Pietermaritzburg, South Africa (RSA)
MSc, Botany, UKZN, RSA 2000
It has long been accepted that mammals were generally small and nocturnal (night active) for the first two thirds of their evolutionary history (≈ 210-65 mya). Indeed, nocturnal activity still predominates among extant mammals. It has also been widely accepted that ancestral primates remained nocturnal and that diurnal (day active) behaviour was a secondary development in some descendant lineages. Early terrestrial vertebrates were probably tetrachromatic, with 4 colour opsin genes corresponding to 4 retinal cone types expressing 4 photo-sensitive pigments, each optimally sensitive to light of different wavelenghts and a rhodopsin gene corresponding to rods cells. The 4 colour opsin pigments were presumably for vision in bright light (photopic vision), whereas rhodopsin in the rods was presumably for vision in dim light (scotopic vision). Following suppression of 2 of the ancestral colour opsin genes, mammals are typically dichromatic, with an M/L-opsin photopigment sensitive to medium/long wavelengths of light and an S-opsin sensitive to short wavelengths of light. Trichromacy is a highly unusual secondary condition among placental mammals, confined to certain diurnal primates, including old world monkeys, apes and humans. As recently as 20 years ago, it was widely believed that nocturnal mammals, including primates, have a pure rod retina. However, a large body of evidence now shows that cone cells are consistently present in the retina of nocturnal mammals. Surprisingly, both M/L- and S-cones are often present, although S-cones have been suppressed in various nocturnal mammals, including 3 groups of primates (lorisiforms, Cheirogaleus and Aotus). This and other evidence has led several authors to propose that primates had a diurnal ancestry. My dissertation research focusses on this enigma, using a phylogenetic analysis of opsin genes within the supraordinal clade, Euarchonta, which includes colugos (Dermoptera) and tree shrews (Scandentia) and through consideration of intraspecific variation in nocturnal species that have retained 2 cone types.
Field Museum Women's Board Scholar 2010-2011