2014 – 2015
Biomedical Honours Student 2015
Thesis Title: Polypterus Fin-Ray Morphology and Actinodin Gene Characterization
Recent work suggests that Polypterus, an extant member of the basal-most group of ray-finned fish, can be viewed as an analogue of stem tetrapods. By comparing the fin-ray morphology of Polypterus to that of teleosts, differences can be explored and potentially attributed to the evolution of the clade. Additionally, by comparing the expression of the actinodin gene, a gene family involved in fin-ray regeneration and believed to be a contributing factor in the fin-to-limb transition in Polypterus to closely related species, inferences can be made on the modification of the expression of the gene closer to the point at which it was lost.
Biomedical Honours Student 2015
Thesis Title: A kinematic analysis of pectoral fins in walking behaviour of the Polypterus senegalus
Using a novel methodology we examined Polypterus senegalus pectoral fin kinematics to help provide insight into terrestrial locomotion and adaptations required in a shift from water to land locomotion. We hypothesized that Polypterus senegalus would have predictable fin placement and force production timing throughout its step cycle on land. Using polarizing filters placed above and below a photoelastic gelatin substrate, Polypterus senegalus body movement was observed. Production of force against the gelatin while walking disrupted uniform light being shined through the substrate allowing the visualization of where force is selectively distributed across the pectoral fin during the P. senegalus stroke cycle. Directional significance (Rayleigh’s test, P<0.05) was observed in the maximum and minimum Nose Fin Angle, as well as maximum Back Lobe Area in Polypterus senegalus (n=8). Directional significance of some kinematic variables helps support the theory that pectoral fins and body work in harmony to generate propulsion during land locomotion in Polypterus senegalus as opposed to only being for body support. Success of new methodology allows for future studies to measure force production in fins if photoelestic gelatin is calibrated. This allows a better comparison of Polypterus with other amphibious fish, and tetrapods.
Biology Honours Student 2015
Thesis Title: A biomechanical comparison of aquatic and terrestrial locomotion in Polypterus using body kinematics
Terrestrial locomotion strategies have been seen in many fish species such as thrashing, tail-flip and axial-based appendage strategies. Polypterus senegalus is a fish of the lineage Polypteriformes that is predominantly aquatic and has similarities to fossil fish (elpistostergid). It is the most basal ray-finned fish that is able to perform terrestrial locomotion using an axial-appendage based strategy; i.e. using their pectoral fins and body curvature. I hypothesize that Polypterus use their bodies differently on land compared with when they are swimming. Polyperturs were filmed walking and swimming using high speed video. Body midlines were digitized every fifth frame to calculate body amplitude and curvature throughout each locomotive cycle. During walking, Polypterus has significantly larger tail oscillation and larger curvature of body compared to swimming. However, during swimming locomotion, Polypterus had a greater number of curves along the body. During swimming the fish did not oscillate their heads and no significant difference was seen between the tail oscillations amplitudes, and curvature for the different swim speeds. Also, during walking there was no significant difference between the amplitudes for the head and tail oscillation. However, there was a difference in the length of path the tail took compared with that of the nose. The results show that there are kinematic differences in body use between the two locomotive strategies used by Poylpterus in terrestrial and aquatic environments.
Group Photo of 2014-2015 UROP Students. Left to right, Marium Nawaz, Emily Standen, Carolyne Godon and Tiffany Dunbar.
Co-op Student Summer 2015
UROP Student Winter 2105
Project Title: Analysis of Polypterus fish fins and their control
I worked on the anatomy and function of fin rays in a variety of ray-finned fishes. My long term goal is to better understand how fin ray function changes in fishes that move both in water and on land.
UROP Student Winter 2015
My UROP project looked at how body kinematics change at different swimming speeds in Polypterus senegalus. I used high-speed videography to film fish swimming in a variable speed flow tank. Body kinematics were analyzed by digitizing images using Matlab and ImageJ.
UROP Student Fall 2014
Project Title: Phenotypic plasticity in the head and neck of an air breathing fish
I am working on a project comparing the head and neck anatomy of Polypterus raised in the water to those raised on land. I will take measurements on micro CT scans to see if there are any differences between these two groups that could help explain the evolution of necks in tetrapods.