Admissions > PhD by research > Research Projects > Ecological selectivity during the Permo-Triassic mass extinction

Ecological selectivity during the Permo-Triassic

mass extinction

Supervisor: Professor Michael J Benton

The normal rules of evolution seem to break down during times of mass extinction. So the characteristics that ensure survival in normal times under natural selection may not operate at times of major crisis. Determining which kinds of organisms died out and which survived can reveal whether there was any selectivity through the event, or whether the extinctions were more or less randomly distributed.

It has commonly been assumed that the victims of extinction events tend to be large, occupied the higher trophic levels of food chains, had small population sizes, and perhaps were dietary specialists. Studies of selectivity through the Cretaceous-Tertiary mass extinction have shown, however, that there was broadly no, or limited, selectivity according to diet, body size, breeding mode, life position (e.g. burrowers versus non-burrowers), and other biological and ecological characters. There is some evidence for geographic selectivity and certainly for survival of cosmopolitan versus endemic species (Jablonski and Raup 1995; Smith and Jeffery 1998).

Very few studies of selectivity have been undertaken for other mass extinctions, and especially not for the largest mass extinction of all time, the end-Permian event. We have developed expertise in studies of a number of fossil groups across the Permian/Triassic boundary (PTB) in Bristol, and a study of selectivity by ecological, distributional, and other characters would be timely. Groups for study might include molluscs, arthropods, fishes, and tetrapods. Key questions are: (1) Was there selectivity by body size, diet, or ecological niche? (2) Are there differences between marine and continental organisms? (3) How did selectivity act, whether during the initial extinction or during the post-extinction recovery period. The project benefits from improvements in understanding of dating across the PTB, but particular consideration of sampling bias will be given based on studies of the rock record and cladistic analysis and identification of ghost ranges.

The project will provide a broad training in numerical methods in palaeontology and macroevolution. The initial exercises will require construction and statistical analysis of large databases: such work requires great care and dedication. It will then be useful to choose one or other of the major groups, and perform some specimen-based study to further refine the ecological and taxonomic assumptions. Sampling studies will rely on databases of geological proxies for rock volume and sea level. The student will have the chance to publish a number of high-profile papers, and to acquire a training that will suit him/her for a range of research positions across the fields of evolution, ecology and palaeobiology.

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Last updated: 26/10/11