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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.

 

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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.

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EARTH SCIENCES DEPARTMENT SEMINAR

 

wiltie dacite.jpg

 

Mixing, mingling and enclave crumbling in the post-Minoan dacitic magmas of Santorini volcano, Greece

 

Chiara Maria Petrone,

Earth Sciences - Natural History Museum

 

Tuesday 29th October - 4.00 pm

Earth Sciences seminar room

(Basement, WEB 05, the previous Mineralogy Seminar Room)

 

 

The post-caldera islets of Palea- and Nea-Kameni formed as a result of nine eruptive events from A.D. 46-47 to 1950 in the center of the Santorini Minoan caldera. The erupted products are represented by dacitic lava flows and domes hosting basaltic to andesitic mafic enclaves. Dacitic rocks have low porphyritic index that increases with time, whereas their degree of evolution decreases pointing to the composition of the mafic enclaves. Enstatite contents of pyroxene and anorthite contents of plagioclase decrease from mafic enclaves to host lavas. Sr isotopes systematically increase with time and toward the less evolved composition of lavas and mafic enclaves, whereas Nd isotopes decrease. Whole rocks and mineral separates of mafic enclaves from the younger events are more Sr-radiogenic than their host lavas, the opposite occurs in the A.D. 46-47 lavas and enclaves.

 

Mixing and mingling processes between dacitic and mafic magmas, along with crumbling of the mafic enclaves in the host lavas are responsible for the observed textural and geochemical characteristics of the dacitic host lavas. The variations of Sr-Nd isotopes with time in the enclave magmas seem to indicate assimilation of limestone from the basement by the most mafic magmas; this process is associated to new mafic magma inputs and femic phase crystallization. A shallow layered reservoir with dacitic magmas overlaying lower mafic magmas is supported by our data. Crystal fractionation and cumulitic processes affect the lower part of the plumbing system allowing further layering of the mafic magmas, generating the variable and complex textures shown by the mafic enclaves. Different portions of the layered reservoir were frequently and variably sampled during time, as testified by variable types, compositions and distributions of mafic enclaves in the different eruptions. All this allows us to suggest periodic arrivals of mafic magmas in the post-Minoan plumbing system of Santorini, also implying for a still active magmatic system whose behaviour needs to be fully evaluated, also in the light of the 2011-2012 unrest.  

 

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

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Coral.jpg

 

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

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Department of Life Sciences seminar

 

Insect diversity and pest control in the anthropogenic habitats of NE China

 

Jan Axmacher

Department of Geography, University College London

 

Friday 7 December 11:00
Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)

 

 

The natural environment of NE China has been altered by humans for thousands of years. Nonetheless, both intensity and spatial extend of these alterations have greatly increased since the middle of the last century. Agricultural production was greatly intensified, while the remaining natural forest cover was widely cleared. The severe environmental degradation which followed has led to an increased awareness of the importance of environmental issues in the last few decades, with re- and afforestation projects being currently established throughout China at an unprecedented scale. At the same time, agricultural practices following the maxim ‘the more, the better’ are also increasingly questioned, with the importance of biological pest control recognized as a potential cheap and less environmentally detrimental alternative to chemical pesticides.

 

Given these recent developments, I have started a number of collaborative research projects with the Chinese Agricultural University and the Institute of Botany, Chinese Academy of Sciences to investigate diversity and species composition of ground beetle assemblages in reforested habitats and the agricultural landscapes of the Hebei province, looking at both the diversity and potential pest control function of these mostly predatory beetles. Our research shows that the diversity of ground beetles varies strongly between different types of forest ecosystems, with naturally regenerating birch forests and open larch plantations showing a high abundance, but low diversity in carabids. Plantations of native oak and pine monocultures, as well as forests composed of a mixture of planted and naturally regenerating trees harbour distinctly higher diversity levels.

 

In the agricultural landscape, even very intensively managed double-cropping systems comprising of summer maize and winter wheat monocultures can support surprisingly high levels of ground beetle diversity, while cotton monocultures were found to harbour distinctly lower levels of carabid diversity. Landscape elements like the diversity of land-use types were found to have only a limited effect on the diversity of the ground beetle community at least in some of our study areas. A comparison of diversity patterns in ground beetles and geometrid moths finally showed that links between these highly diverse herbivore and insectivore taxa are highly complex, with distinctly different spatial patterns observed in these two families.

 

 

 

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

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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

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Tuesday 23rd October
Neil Chalmers Seminar Room (DC2. LG16), 11:00

 

Biodiversity through Time – Why Understanding the Rock Record Matters

Dr Andrew SMITH, Earth Sciences, The Natural History Museum

This seminar is part of the new MRes course jointly organised by UCL, the NHM and the IoZ. Although this is primarily for the benefit of the MRes students, if you would like to attend, please feel free to do so. 

 

 

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

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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.

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Entomology Seminar

 

Alfred Russel Wallace in the New World: Wallace's US-Canada Lecture Tour of 1886-87

 

Charles H. Smith

Western Kentucky   University, USA

 

Wednesday September 14th

Neil Chalmers Science Seminar Room (DC.LG16)

 

2 pm - 3 pm

 

Alfred Russel Wallace is best known for events that took place relatively early in his life, in connection with his natural history collecting expeditions to South America and Indonesia in 1848-52 and 1854-62, respectively. But after returning the second time to England he lived another fifty-one yearsto the age of ninety in 1913. This later portion of his life was also filled with activity, and even included another lengthy period of time spent out of the country. Over a ten month period in 1886-87 he toured some ten thousand miles across Canada and the United States, along the way observing, lecturing, botanizing, attending séances, and meeting and befriending a couple of hundred leading figures from American science, politics, and academia, right up to President Grover Cleveland. He left a journal of his tour which is most enlightening, and currently under transcription for publication. In this presentation, focussing on the journal, we attempt a return to this late-Nineteenth Century world.

 

Contact: Dr Vladimir Blagoderov, Entomology (v.blagoderov@nhm.ac.uk)

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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

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Palaeontology  Seminar - Cranial morphology of fossil  hybodont sharks: new information from CT scan studies

Thursday - TODAY - 7th April, Neil Chalmers Seminar Room, DC2,  16:00

Dr.  Jennifer Lane, Bayerische Staatssammlung für Paläontologie und Geologie,  Munich

 

The  growing field of palaeontological CT scanning has only recently begun to be  applied to fossil chondrichthyan fishes (i.e., sharks, rays, and chimaeroids).  In recent years, CT scan-based studies have provided new information on  chondrichthyan cranial morphology, particularly regarding internal features such  as the interior surface of the braincase and the inner ear.

 

Many of these  features have turned out to be significant in shedding new light on patterns of  chondrichthyan evolution. Hybodonts, the sister group of modern sharks, are of  particular interest in what they can reveal about the evolutionary history of  their living relatives.

 

The inner ear of modern sharks (neoselachians) is highly  adapted toward low-frequency semi-directional sound detection (LFSDP). New  investigations of two fossil hybodonts (Tribodus limae and Egertonodus basanus) using  high-resolution CT scanning confirms that the structure of the inner ear in  these sharks was also adapted for LFSDP. However, this adaptation is absent in  earlier chondrichthyans (e.g., symmoriiforms, ctenacanths, Pucapampella), suggesting that it arose  only after the divergence of the hybodont/neoselachian lineage from these  earlier groups. Other features of evolutionary interest include.the loss of the  cranial fissures and elaboration of the vagal and glossopharyngeal nerve canals;  development of a medial capsular wall; and changes in patterns of cranial  arterial circulation.

 

In facilitating identification of key features such as  positions of nerve and blood vessel pathways and foramina, CT scanning and  digital reconstruction techniques may also pave the way for future developmental  studies (such as reconstructing the positions and growth patterns of the  embryonic cranial cartilages).

 

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

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Friday April 8th
Flett Theatre

 

11:30 am - 12:30 pm


Larval morphology  of the forensically important Muscidae of Europe


Andrzej  Grzywacz
Nicolaus Copernicus University, ToruÅ„,  Poland


The Muscidae is a large  dipteran family of some 4500 species and with a cosmopolitan distribution. Many  species exhibit various degrees of synanthropy, and some are important from a  medical and veterinary point of view, like those attracted to decaying organic  matter (e.g. decomposing bodies). Housefly species on decomposed bodies, both as  larvae and adults were found in carrion experiments and death investigations.  Application of methods  of Forensic Entomology requires proper species  identification of collected material.


The morphology of immature stages in  carrion visiting houseflies is unequally studied. In some species immature  stages are not described and in the others only some stages are known. On the  second hand characters used in some keys do not allow to easy species  identification. It results in serious problems with identification of immature  houseflies in forensic cases.


During an ongoing project morphological data  concerning the immature stages of all European species of Muscidae of forensic  importance will be revised. Results will be used to prepare an identification  key for the larvae of forensically important species. For this purpose results  obtained during this visit in Natural History Museum will be essential, as also  for the future research projects concerned on larval morphology of Muscidae and  Fanniidae.

 


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