Microfossils and Evolution
18th November, 2009
Room 1.06, Roberts Engineering Building, University College London
Following the conclusion of Society business, Michal Kucera and David Lazarus introduced an excellent series of talks on the topic of Microfossils and Evolution, celebrating the Darwin Bicentenary.
The first speaker was David Bass from the Natural History Museum, London, whose title had evolved from his original one into ‘The Nth eukaryotic ‘supergroup’ and the evolutionary and ecological complexity of the Rhizaria’. David entertained us with comparisons between the eukaryote ‘bush of life’ and ‘tree of life’ and presented some interesting new data from 454 sequencing of DNA libraries.
Phil Donoghue from the University of Bristol followed and began by reminding us that Darwin’s On the Origin of Species contained a damning reference to the utility of the fossil record! Phil then presented some elegant computer tomographic imagery of some exceptionally well preserved fossil embryos from the Precambrian. Astonishingly large samples are required in order to find the embryos; Phil talked about one sample of 12 tonnes that yielded 600 embryos (~ 1 gramme)! He also concluded that encysted fossil embryos are predisposed to fossilisation, more so than larval stages or animals following hatching.
Charles Wellman from the University of Sheffield talked about the timing of the emergence of fossil plants. He summarised the debate about the first good evidence for land plants and showed his evidence that this was mid Silurian cryptospores, suggesting that Cambrian evidence was algal remains. He stated that this represented a change from gametophyte-dominant (e.g. bryophytes) to sporophyte-dominant vascular plants.
Koenraad Martens from the Museum of Natural Sciences, Brussels, talked about the paradox of sex. Given that sex is very costly in evolutionary biological terms, why is sex so successful? Koenraad talked about the ostracod Eucypris virens which has 3 genders (sexual male, sexual female and asexual female) and was discovered, following genetic analysis, to have 37 cryptic species that can not be identified morpologically!
Paul Pearson from Cardiff University discussed the evolution of Cenozoic planktonic foraminifera and developments that have resulted from stratophenetic sampling. He presented a new synoptic morphospecies phylogeny, developed by Tracy Aze (Cardiff University) as part of her PhD research, and went on to discuss the problems of anagenesis and the need to get rid of pseudo-speciations and pseudo-extinctions that result from the splitting of a gradually evolving lineage into different species.
David Lazarus from the Museum für Naturkunde, Berlin, talked about the problems of investigating the evolution of radiolaria – the fact that no catalogues exist for extant radiolarians, let alone fossil one, which limits the use of traditional macroevolutionary analysis using diversity curves and databases. Many fossil taxa have not been described properly yet, under-recording primary diversity, however, David presented some new data from Renaudie and Lazarus that demonstrated a huge increase in radiolarian diversity in the middle Miocene. He concluded by saying much more work needs to be done with radiolarians to address the really important evolutionary questions.
Following the lectures, members of the Society were invited to a wine reception, generously sponsored by PetroStrat Ltd