Evans Honours Projects

Power Cascade Law of Growth in Animals and Plants

Background: The Evans EvoMorph lab has recently discovered a new law of growth that controls the shapes of teeth, horns, claws and thorns in plants and animals. This new law is called the ‘power cascade’ and it determines the shapes that are most commonly made for these structures according to a simple power law. The power cascade is present in vertebrates (from fish and amphibians to dinosaurs and mammals), invertebrates (including insects, spiders and squid) and plants (such as lemon tree and rose bush). When the power cascade controls the default shape for structures, this significantly influences the shapes that evolve in animals. We have shown that it can estimate the age of elephants from the growth of their tusks, and predict the shapes of Tyrannosaurus teeth. Computer simulation of growth following the power cascade can replicate the final shape of these structures.

Project Aims:  This project will examine how the power cascade affects the growth and evolution of structures in a range of organisms, from insects to plants, depending on the interests of the student. This may include the shapes of leaves, insect bodies or whale teeth. Computer simulations of growth can be used to further discover how growth influences the evolution of shape

Techniques:  This project will use a variety of 3D and 2D imaging and analysis techniques to measure the shapes of structures. For 3D data, we use microCT and medical CT imaging and laser 3D surface scanning, and then process data in 3D software (Avizo, Geomagic, Blender). For 2D data, we use ImageJ for processing and measurement. Computer simulation of growth can use Mathematica or custom-built developmental simulation software.

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Evolution and Feeding of Kangaroos and Wallabies

Background: Kangaroos and wallabies are the most successful group of terrestrial marsupials in Australia, being adapted to a wide variety of environments from rainforests to deserts and consuming fungi to grass. The Evans EvoMorph lab is investigating aspects relating to diet, growth and environment of kangaroos and wallabies. Some potential topics include:
Continuous tooth replacement in the nabarlek: The little rock wallaby, or nabarlek, is a unique marsupial that can continuously produce new teeth when the old ones wear out. We are investigating how this process works, and how we can determine the age of these animals.
Fossil record of giant kangaroos: We have a very good fossil record of the recent ancestors and relatives of modern kangaroos, including giant kangaroos. The teeth of kangaroos trap chemical elements that reveal a lot about their environment and diet. We can examine fossils of kangaroos to determine their age, diet and environment, including the presence of drought.

Project Aims: This project will examine various aspects of feeding, tooth and bone biology of kangaroos and wallabies, ranging from modern to extinct species.

Techniques: This project will use a variety of 3D imaging and analysis techniques to measure the shapes of teeth and jaws. For 3D data, we use microCT and medical CT imaging and laser 3D surface scanning, and then process data in 3D software (Avizo, Geomagic, Blender). We may also use elemental or isotopic analysis of teeth and bone.