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Palaeontological and developmental approaches for resolving vertebrate phylogenetics and character evolution

Palaeontological and developmental approaches for resolving vertebrate phylogenetics and character evolution

Supervisor: Dr Rob Asher

Co-supervisor: Dr Jason Head

Project summary:

We seek to understand vertebrate evolution by applying methods in comparative anatomy, development, and phylogenetics. Many branches on life's evolutionary tree were well-established by the close of the 19th century; others have been resolved more recently; and yet others remain contentious. Resolving the tree of life is important both in applied and theoretical biology, e.g., in interpreting animal models and testing hypotheses of character acquisition (respectively). Data relevant for phylogenetics come from many sources, including development, adult phenotype, and genetics. Patterns of growth (e.g., dental eruption and in formation of the axial skeleton), have proven to be informative for key branches of the mammalian tree of life. Only a subset of these data sources are typically available for fossils, yet most species that have ever existed during the course of Earth History are now extinct. Methods to reconstruct and assesses confidence in phylogenetics (particularly among fossils) are therefore key. By applying palaeontological datasets to test phylogenetic questions for species with well-corroborated positions on the Tree of Life, we can gauge the accuracy of a palaeontological dataset relative to soft-tissues and DNA. We will also extract character data from vertebrate species using histology and microCT, combining with DNA where feasible.

What the student will be doing:

The student will formulate and test hypotheses on vertebrate evolution by collecting comparative anatomical data on living and fossil species using collections-based research, microCT, and/or histology. Heuristic tests of phylogenetic accuracy based on subsets of hard vs. soft tissues and DNA may also be undertaken. Where available, the student will also collect data on developmental changes to phenotype during the course of growth. This project entails training in comparative anatomy, phylogenetic methods, digital imaging in microCT and/or histology. A background in biological systematics and vertebrate comparative anatomy are both essential. Familiarity with computer programming/scripting is helpful.

References:

Asher RJ, Bennett N, Lehmann T. 2009. The new framework for understanding placental mammal evolution. Bioessays 31(8): 853-864.

Head JJ, Polly PD. 2015. Evolution of the snake body form reveals homoplasy in amniote Hox gene function. Nature. 2015 Apr 2;520(7545):86-9.

Pattinson DJ, Thompson RS, Piotrowski A, Asher RJ. 2015. Phylogeny, paleontology, and primates: do incomplete fossils bias the tree of life? Systematic Biology 64(2):169-186.