Qualifying Examination
“Morphological and Chemical Evolution in Sepsidae: An Evolutionary Approach to Phenomics and Shape Analysis”
Pitta de Araujo, Diego
Graduate Student
Dept. of Biological Sciences, NUS
Tues, 23 April 2013: 10.00am
@ DBS Conference Room (S3 Level 5)
Supervisor: Prof. Rudolf Meier
Co-Supervisor: Dr. Joanne Yew
All are welcome
Abstract:
“New advancements in morphological and chemical analysis are promoting a renaissance of the studies of phenotypes in the era of genomics. Here I propose to use a “phenomics” approach to fully explore the morphology and chemistry of Sepsidae flies. These flies have very complex and variable morphological structures most of which are used in sexual behaviour and serve as a model clade to study phenotypic evolution. I am combining several morphological imaging techniques (Visionary Digital, Light Microscopy, Confocal Microscopy and Scanning Electron Microscopy) and chemical imaging (Ultra-Violet Laser Desorption Ionization Mass Spectrometry) to understand key changes during sepsid evolution. The three main questions that be addressed in this research are: How much morphological and chemical change happened in the evolution of Sepsidae? Is there a phylogenetic pattern and correlation among different phenotypes? How to quantify morphological change in an evolutionary context?
I carried out a detailed morphological and chemical study of the mysterious osmeterium, a gland that is located on the hind tibia of males. I use UV-LDI Mass Spectrometry to solve the identity of its secretion, the time of secretion, and the secretion’s fate when it is transferred to the female’s body during mating. My preliminary morphological results pertain to the morphology of the head capsule and mouthparts and indicate variation among species, mainly with regard to the structure of the head capsule. For this part of the flies’ body there is little evidence for sexual dimorphism. The thorax morphology of sepsids varies among species with regard to the shape of thoracic plates and patches of micropilosity. I am also the first entomologist studying the male intromittent organ in sepsids and document its variation across the species.
Lastly, I propose to explore new tools in 3D design to create representations of morphological structures. I propose to use new techniques in shape analysis for advanced 3D visualization and shape measurement: evolutionary morphing, shape similarity and shape complexity. With these tools I hope to quantify and visualize how sepsid morphology changed over evolutionary time.”
The Biodiversity Crew @ NUS 