4 South 1.07
2009 MRes (Distinction) Biosystematics – Imperial College London & Natural History Museum
Project 1: Delimiting Evolutionary Taxonomic Units within the Bacteria: 16S rRNA and the GMYC Model.
Project 2: Atlas of the Caecilian World: A Geometric Morphometric Analysis.
Project 3: Pteropoda of the Southern Oceans: A Large Scale Molecular Phylogeny.
2007 MSci (2:1) Palaeobiology – University College London
Dissertation: Dental Microwear Herbivorous Lizards and Sauropod Dinosaurs
Macroevolutionary Trends: Morphological disparity through time
Natural selection is often erroneously equated with the gradual exploration of design possibilities through time. The evolution of life is traditionally depicted as a cone of increasing diversity, originating and expanding from some point prior to the Cambrian. It was assumed that the diversity in form (disparity) that organisms can occupy would mirror this trend. However many modern phyla have body plans with a fossil record extending back to the Cambrian: a time when diversity was low. Disparity and diversity therefore appear to be decoupled. Morphological disparity refers to the range or spread of anatomical design displayed by a sample of organisms. It is distinct from taxonomic diversity, which is a direct function of the number of species sampled.
Within the last two decades, a limited number of case studies have compared patterns of diversity and disparity in the radiations of large clades. Some explore morphospatial extremes prior to a peak in diversity early in the clades history (blastozoans, crinoids, carnivorous mammals), while others show early high diversity accompanying low disparity (trilobites, pterosaurs) or a tandem increase of the two (acritarchs, acanthomorphs). However many questions remain unanswered:
- Is the pattern of early high disparity seen in the majority of published studies the prevalent trend, or is it a function of the groups so far investigated?
- Does the precise pattern depend upon the taxonomic level of the analysis and the time of the radiation?
- Do mass extinctions leave high residual disparity despite their devastating effects on diversity?
- To answers to these questions I am currently analysing morphological datasets for clades across the Metazoa, combined with published stratigraphic data spanning the Phanerozoic.
The Willi Hennig Society (Cladistics)
The Systematics Association
The Palaeontological Association (Palaeontology)
The Society of Vertebrate Paleontology (Journal of Vertebrate Paleontology)
The Society of Systematic Biologists (Systematic Biology)
The Leverhulme Trust: 3 years
Barraclough, T.G.., Hughes, M., Ashford-Hodges, N., Fujisawa, T. 2009. Inferring evolutionarily significant units of bacterial diversity from broad environmental surveys of single locus data. Biol. Lett. doi:10.1098/rsbl.2009.0091 Link