Friday 28 Mar, 4.30pm

Neil Chalmers Seminar Room, DC2

The Evolution of Vertebrate Reproduction

by Zerina Johanson, Department of Earth Sciences

The early history of the jawed vertebrates, and the evolutionary transition from jawless to jawed vertebrates, is recorded entirely in the fossil record. Phylogenetically, the most basal jawed vertebrates (and some of the most crownward stem gnathostomes) are the placoderms, fossil taxa ranging in age from the early Silurian to the end of the Devonian (435-360mya). As such, placoderms record the origins and evolution of a number of major jawed vertebrate morphologies. A re-examination of the superb three-dimensionally preserved placoderms recovered from the Gogo Formation (Late Devonian, Western Australia) has provided the most detailed knowledge of this group to date.

We review recent information on placoderm embryos as well as previous descriptions of the placoderm pelvic structures and reinterpret the morphology of the pelvic region, in particular the position of the pelvic fin and the relationship of the male clasper to the pelvic girdle. Claspers in placoderms and chondrichthyans develop in very different ways; in sharks, claspers develop from the pelvic fin while the claspers in placoderms develop separately, suggesting that their independent development involved a posterior extension of the ‘zone of fin competence’.

SciFri is a cross-departmental science seminar series and social event, held on the last Friday of each month. The 45 minute talks are intended to be informal, contemporary, inter-disciplinary and cover a range of fields including the latest research, curation, science policy, library & archives research, publishing, media, fieldwork and science methods.

Conservation of reef corals of the world: why phylogeny matters

Danwei Huang

Postdoctoral scholar, University of Iowa

Friday 18 October 11:00
Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)

One third of the world's reef-building corals are facing heightened extinction risk from anthropogenic climate change and local impacts. Extinction probabilities aside, species are not equal. Rather, evolutionary processes render each species, or species assemblage in general, unique with a distinctive history that can be characterised for conservation. My research is aimed at quantifying these patterns based on a robust understanding of the coral tree of life. In this talk, I will show that it is critical to consider species' contribution to evolutionary diversity in conjunction with their extinction risk when setting priorities to safeguard biodiversity.

My analyses identify the most endangered lineages that would not be given top priority on the basis of risk alone, and further demonstrate that corals susceptible to impacts such as bleaching and disease tend to be close relatives. One of Earth's most threatened reef regions, the Coral Triangle, is also famously the most biodiverse. While competing ideas are plentiful, the dynamics underlying this biogeographic pattern remain poorly understood. Phylogenetic modelling adds a valuable dimension to these explanations, and can help us uncover the evolutionary processes that have shaped coral richness in the hotspot. Indeed, conservation of the world's reef corals requires protecting the historical sources of diversity, particularly the evolutionarily distinct species and the drivers of its geographic diversity gradient.

For additional details on attending this or other seminars see http://www.nhm.ac.uk/research-curation/seminars-events/index.html

What can psyllids tell us that other bugs can't?
A non-model model organism for studying plant-insect interactions

Diana Percy

Terrestrial Invertebrates, Dept.of Life Sciences, NHM

Wednesday 28 of November 11:00
Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)

Psyllids exhibit the greatest degree of host specificity amongst the sternorrhynchan plant-feeders, and they are the only members of this group to have retained a complex vibrational communication system [sound and light show includes backup band]. But can psyllids reveal things that studying other bugs can't? I will present examples of how systematic analyses of psyllid lineages can provide remarkable insights into host mediated diversification. From modest beginnings of “who eats what where?”, we can build up a picture of how these observed plant-insect interactions came to be. Combining these observations with molecular systematics and genomics approaches will help us interpret the past and look into the future to make predictions of “who will eat what where?” – the psyllid version of “eats shoots and leaves”.

For additional details on attending this or other seminars see http://www.nhm.ac.uk/research-curation/seminars-events/index.html

Zoology Seminar


TUESDAY 28th February, 12 noon

Neil Chalmers Science Seminar Room  (DC.LG16)

Contact: Ronald Jenner, Zoology

The Mysterious World of Vampire Amoebae and  Plasmodiophorid Plant Parasites

Sigrid NEUHAUSER & Cédric  BERNEY
Department of Zoology, NHM

Vampire amoebae  (Vampyrellida) and plasmodiophorid plant parasites (Phytomyxea) have been known  since the second half of the XIXth century, yet have been given very little  attention up to now in spite of their fascinating biology. The taxonomic  position of both groups has been much debated for over a century, but recent  molecular work showed them to be sister lineages within the eukaryotic  supergroup Rhizaria. From their common ancestor, the Vampyrellida evolved to  become super-predators of algae, fungi and other microorganisms in all marine  and terrestrial microbial ecosystems, with some species adopting a peculiar mode  of feeding that earned them the name of vampire amoebae. In contrast, the  Phytomyxea evolved to become obligate, endobiotic parasites of higher plants,  diatoms, brown algae and oomycetes. Members of this group can cause devastating  and significant plant diseases (e.g. Plasmodiophora brassicae causing  clubroot disease), while others will spend their life hidden inside their hosts  without causing any visible symptoms. As part of our research group’s focus on  the biodiversity, evolution, and ecological importance of poorly known members  of the Rhizaria, we will present some of our results and illustrate the  enigmatic nature and contrasting lifestyles of vampire amoebae and  plasmodiophorid plant parasites.

Palaeontology Department Seminar

Thursday 1st September Neil Chalmers Seminar Room, DC2, 1600

Sampling, modelling, and making sense of the fossil record of diversity

Dr. Andrew B. Smith, Department of Palaeontology, NHM

While we can sample the available rock record effectively for its fossil content, the record we are sampling is itself biased.  Understanding and quantifying this bias is key to developing better estimates of diversity over time, and various ways of estimating rock record bias have been proposed.  Recent criticisms of these approaches by Benton and co-workers are shown to be misplaced or unfounded.

To demonstrate by how much the fossil record is distorted by unavoidable sampling inequality, the diversity of planktonic microfossil clades are estimated from two independent records – that of land-based outcrops and deep-sea cores.  These differ markedly, with each tracking its respective record of rock accessibility over time. However, modelling and subsampling approaches to the two very different records converge on a single underlying pattern, showing that these are powerful approaches for recovering less biased estimates of how past diversity has changed over geological time.

Contact: Greg Edgecombe g.edgecombe@nhm.ac.uk

Contact: Vladimir Blagoderov - vlab@nhm.ac.uk