The Micropalaeontological Society

Annual General Meeting 2001

The Annual General Meeting was held on 21st November at University College London.

Following Society business, two talks were presented.

Microvertebrates and macroevolution – unravelling the origin and early history of the vertebrate clade
Dr Paul Smith, Dr Philip Donoghue and Dr Ivan Sansom (School of Earth Sciences, University of Birmingham)

The study of Early Palaeozoic microvertebrate faunas has, in the last decade, had a major impact on the understanding of vertebrate palaeobiology. A review of pre-Silurian vertebrates carried out as recently as 1991 concluded that only five species could confidently be included in the clade. Since then, a number of key discoveries have been made, many of them reliant on micropalaeontological methodologies. For example, the first armoured fish are now known to be present in the Late Cambrian, and the biodiversity of Ordovician vertebrates is far higher than previously suspected, even at high taxonomic levels. One particularly important change has been the increasing recognition that conodonts are vertebrates, which has both changed the temporal perspective of vertebrate phylogeny and increased the known generic and specific diversity by two orders of magnitude. Together, these developments demonstrate the importance of integrating micropalaeontological and traditional, vertebrate macrofossil, datasets since neither picture is complete in itself. The new discoveries have a significant part to play in elucidating the phylogeny of the group and in testing evolutionary scenarios, in assessing the completeness of the fossil record of early vertebrates, and in the determination of biogeographic and large-scale ecological patterns and processes.

Coccolithophore species – results from CODENET (Coccolithophorid Evolutionary Biodiversity and Ecology Network)
Dr Jeremy Young (Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD)

In 1997 we (VU Amsterdam, ICM-Barcelona, U. Bremen, AWI-Bremerhaven, U. Caen,  U. Lisbon, Netherlands Institute for Sea Research, U. Oviedo,  ETH-Zurich) were successful in obtaining EU funding for a Training and Mobility of Researchers network project, CODENET, to train young scientists in interdisciplinary research and carry out basic research into coccolithophorid ecology, microevolution and phylogeny. The project was focused on six key species and included culture isolation; studies of cytology, morphogenesis, life-cycles and pigments; calibration of oxygen isotope, Sr/Ca, and alkenone palaeoproxies; plus taxonomic synthesis and molecular genetic study. This work was planned to: “(1) Probe high-level diversity in key aspects of coccolithophorid biology; (2) build a representative suite of case studies in species-level diversity and microevolutionary processes and (3) advance our understanding of the ecology of extant coccolithophorids and palaeoceanographic information recovery from fossil coccoliths.”

The project is now nearing its end after some three and a half years of gratifyingly productive research (it formally ends on 30th Sept 2001). This talk will briefly overview the project as a whole and discuss the potential this type of research for micropalaeontology in general. I will then focus on one topic which brings together a range of interesting research – microevolution and species concepts.

As with most microfossil groups there has been a strong tradition in coccolith studies of detailed morphometric study of key taxa and lineages, both to understand evolutionary process and to refine biostratigraphy. There has, however, remained considerable uncertainty about the correlation between such morphospecies (often based on rather arbitrary size definitions) and biological species. Within the CODENET project we were able to combine detailed morphometric study of key species in the geological record, in sediment traps, in plankton samples and in laboratory cultures. In parallel with this we used the laboratory cultures to investigate both ecophenotypic variation in selected strains and molecular genetic differentiation between multiple strains. Finally life-cycle studies have provided an unexpected source of additional information, from comparison of coccolith differentiation in the haploid and diploid phases.  The work is at varying stages in the six taxa being studied but a rather consistent pattern is emerging. It appears that the individual species consist of a small set of closely-related sub-species/genotypes with distinct morphologies and discrete ecological preferences; but with overlapping geographical ranges and each with essentially global distributions.  This pattern does not fit easily with either allopatric or sympatric models of microevolution, but does correlate well with biostratigraphic observations of very low diachronism and endemism in calcareous nannofossils.