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August 2011
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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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Biomimetics of Water

Posted by John Jackson Aug 19, 2011

Andrew Parker is a Research Leader in the Crustacea Research Group in the NHM Zoology Department.  He writes:


Animals and plants capture or store water in efficient ways where water is scarce. This research into biomimetics of water has the ultimate aim to manufacture devices that can collect, filter and store water in dry regions of the Earth, which are set to expand rapidly with the progression of climate change.


This work falls into the subject of biomimetics – extracting good design from nature. It involves a collaboration with physicists, chemists, mathematicians and engineers at the Massachusetts Institute of Technology (MIT), which was instigated by National Geographic magazine, who dedicated a feature article to the independent but uniquely related work of the MIT and NHM groups (April 2008).


The subjects we cover are diverse, and include the water collecting mechanisms in various beetles and lizards, hydrophobic and hydrophilic surfaces in plants, and the mechanisms by which diving birds can maintain an air layer beneath their feathers while submerged. Within the physical sciences, we consider the mechanics of flow in fluids, and the interaction of fluids with surfaces, including hydrophobic, hydrophilic and pining behaviours of fluid drops, such as that observed when dew drops cling to certain leaves.


Our research begins with electron microscopy to understand the 3D architecture of the biological surfaces at the micron and nano levels. In other, specialized microscopes, drops of water and other liquids (with different fluidic characteristics) are placed on the biological surfaces and their “contact angles” are measured. This provides data on how well different liquids “ball up”, and therefore the degree of water repellency, for instance. Then, calculations are made to explain how each biological surface is responsible for its precise water properties. From here, new surfaces can be designed to solve precise liquid problems in industry, along with solving water capture problems in hot environments.


The micro-structure I found on the back of a Namibian “darkling” beetle (Stenocara sp.), with combined hydrophobic and hydrophilic surfaces, efficiently captures water from wind-borne fogs. This has been manufactured in plastics for use in air conditioning systems, where it recaptures water leaving the system as vapour, which can be recycled. Further, the hot water vapour no longer contributes to warming the atmosphere.


The overall aim of this research is to produce a prototype device to be employed in developing countries to collect clean water for drinking. This device will feature as many adaptations found in nature as possible, enhanced by the superior materials available in the industrial world.


The device may well contain the Namibian beetle device, since 22 different countries are subjected to desert fogs yet are short of rain. It may draw water from damp soil (rather than from more accessible puddles) in the manner of the Australian “thorny devil” lizard (Moloch horridus) or the xylem system of plants. It may filter water to make it safe for drinking as occurs in the cuticle of certain beetles, self-clean its surface as known in some plant leaves and butterfly wings, and channel and store water efficiently and safely as evident in burrowing desert frogs. Additionally, other biomimetic devices such as “moth-eye antireflectors” and “beetle heat dissipaters”, known to improve solar cell efficiency, will be incorporated where a renewable energy source is required.


Above all, the device must be resilient in the field. To achieve this, we are holding competitions at MIT (in the manner of their famous robotics competition), encouraging students to design the most practical device that may be employed in the Skeleton Coast area of Namibia. This device should showcase several new, bio-inspired technologies that are each ripe for commercialization in disparate industries.


For instance, there may even be spin offs in oil repellent surfaces, and in non-salty water collection for ships and boats at sea. Already, there have been several transatlantic visits between the NHM and MIT, and we have achieved breakthroughs such as understanding the depths to which a bird can dive based on the nanostructure of a single feather.


Most recently we have received vital support from two government ministers in South Africa, so hopefully the politics of employing our devices in Africa will keep pace with our scientific progression, and we can achieve our ultimate goal.

 

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Greg Edgecombe in the Museum's Palaeontology Department has collaborated with Australian colleagues on the investigation of fossil eyes from the early Cambrian period (515 million years ago).  They published their findings in the prestigious journal Nature at the end of June.


The fossils were found in the Emu Bay shale - a very finely grained rock formed from mud - from Kangaroo Island in South Australia.  Shales can preserve fossil organisms in incredible detail, and those from the Cambrian have yielded an amazing diversity of invertebrate animals that lived in marine environments - those of the Burgess Shale in western Canada are probably the best known.  The Cambrian is of particular interest in evolutionary terms because it was a period at which many new groups of organisms are first seen - the term "Cambrian Explosion" is often used to describe the fantastic and rapid diversification of life in a relatively short geological period.


A fair amount is already known about the eyes of trilobites from this period - their eyes were biomineralized (containing minerals) which meant that the fossils are very well preserved.  However, Greg and his colleagues found fossil eyes that do not seem to have been mineralized - much more delicate structures that have only been preserved because of the exceptional nature of the shale fossils.


The eyes appear to be relatively similar to the compound eyes of modern arthropods - they are around 5-7 mm across and contain around 3,000 individual lenses (ommatidia).  The lenses in the centre of the eye are larger, with a falling gradient in size towards the edge of the eye - creating a bright zone for better sight in lower light.  This structure is characteristic of a modern mobile predator such as a robber fly - more advanced than those of trilobites and not seen in other fossils for a further 85 million years. This emphasises the apparent rapidity and complexity of evolution in this early period.

 

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The fossil eyes have similar characteristics to those of modern predatory arthropods such as this robber fly

 

However, a puzzle is that the eyes do not seem to be associated with any identifiable organism in the shale, such as Anomalocaris. It seems possible that the eyes may have been shed in moulting, but by which animal remains to be seen.


 

Lee, M. et al. 2011 Modern optics in exceptionally preserved eyes of Early Cambrian arthropods from Australia. Nature 30 June 2011 474 7353 631-634 http://dx.doi.org/10.1038/nature10097

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Thanks to a collaboration between the Tropical Andean Butterfly Diversity Project (TABDP, which is a University College London, NHM and Darwin Initiative project)  and the Butterflies of America project (BoA) , we now have a unique online archive of photographs of the type specimens of Neotropical butterflies - butterflies from the tropical areas of the Americas.

 

 

 

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This project has a number of purposes and benefits. 

 

  • First, the list of butterflies is a checklist - a list used to define all the species found in a particular area. This is important because it summarises current knowledge of diversity: biodiversity scientists and conservation professionals know what has been found and what they should take account of in research. The act of compiling a checklist will often involve research and reorganisation of collections to reflect current knowledge
  • Second, these are photographs of the type specimens - the definitive reference specimens used as authority for the use of a scientific name.  These are housed in museums such as the NHM in a number of different locations. A virtual photographic collection allows scientists to see easily where the reference specimens are for use - and the photograph may be sufficient for some scientific uses.  It also brings together specimens from different collections that would not otherwise be brought together without considerable cost.
  • Third, the photographs can help in identification and mean that scientists and conservation workers in different parts of the Americas can use the resource as a reference - this may need some care and development of more complex identification resources, such as keys, but the pictures are an important resource nonetheless.


The great majority of these images are scans of print photographs taken by Gerardo Lamas over many years of research in museums throughout the world, and we are very grateful for his generosity in allowing them to be made available. Scanning and initial databasing of the prints was completed by TABDP, supported by the Darwin Initiative, and then given to BoA to be made available online. BoA's Nick Grishin designed and wrote the web pages that now display the images. Numerous other people deserve acknowledgement, including the curators of the museums where these types are housed and many other members of TABDP, BoA and other lepidopterists who contributed images, time and encouragement. 

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This international conference will be held from the 6th-7th December, 2011, on the general theme of South Asian natural history collections with a special emphasis on the collections of the Danish botanist Nathaniel Wallich (1786-1854), a major figure in the history and development of botany in the nineteenth century.

 

As superintendent of the Calcutta Botanic Garden (1817-1846), he undertook botanical expeditions, described new plant species, amassed a large herbarium, collected thousands of plant specimens and commissioned local artists to draw beautiful botanical watercolours. His work has thus been influential in South Asian Natural History research.

 

This conference will explore the challenges associated with exploiting such collections and the interesting opportunities they provide for interdisciplinary research. In particular, the conference will consider the experience of the recent “Wallich and Indian Natural History” project as an interesting exemplar (a collaboration with the British Library and The Royal Botanic Gardens, Kew). An earlier blog post outlined some of the work of this project.

 

Major South Asian natural history collections from the 18th and 19th century are now dispersed across institutions in South Asia, Europe and beyond. Thus, the conference will be hosted by the Natural History Museum, London and the Royal Botanic Gardens, Kew in partnership with the British Library. This conference plays an integral part in the World Collections Programme funded project “Wallich and Indian Natural History”.

 

More information is available on the NHM Centre for Arts and Humanities website. A full programme and travel information will be available on that site by the 30th September, 2011. Abstract Submission Deadline: 30th August, 2011

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Recently, a group of Scientists from the NHM (Shelley Cook, Ralph Harbach, Lorna Culverwell, Erica McAlister, Entomology; and David Bass, Zoology) and a research student from the University of Oxford (Ed Glucksman) joined forces with Unité des Virus Emergents, Marseille, Université de la Méditerranée (Gregory Moureau and Laurence Bichaud) for a cross-disciplinary collecting trip.

 

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Ralph apparently playing Crazy Golf, but he and Erica are in fact collecting adults and immatures…..

 

 

The aims of the trip, conceived by Shelley, were threefold; firstly, the Collection of voucher specimens of mosquito species present in the region for morphological and molecular identification work, and for the Collections here at the Museum. Voucher specimens simply means specimens that are collected and kept in collections for reference – in contrast to simply identifying in the field or lab and not keeping them. In total, approximately 100 mosquitoes will be processed for voucher work, which includes both morphological and molecular characterisation, and many more flies will be added as well. The molecular analysis will be for specific DNA sequences that are now widely used in molecular identification – often called DNA barcodes.  These use mitochondrial cytochrome c oxidase subunit I and II (COI and COII sequence).

 

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Preparing to use the aspirator - a device for sucking up insects

 

The second aim was the collection of bulk samples of adult and immature mosquitoes onto dry ice for screening for flaviviruses; 2010 saw the first two cases of dengue fever (caused by a flavivirus) in patients in metropolitan France (near Nice) with no history of travel and whom were most likely to have been infected by mosquitoes from a local population. In total, approximately 2000 samples were plated for later screening. Previous similar studies conducted by our group have shown a prevalence of novel flaviviruses of up to 10%. Any virus positives will be isolated, characterised and sequenced before publication in scientific journals..

 

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Shelley concentrating on numbering samples

 

 

And thirdly, together with David Bass from Zoology, the collection of a range of plant, water and insect specimens were put into liquid nitrogen followed by extraction of small RNA fractions. These will be tested via Illumina sequencing to test whether this method can detect signatures of viral infection and to compare viral biodiversity across a range of environmental samples - including in particular in association with mosquitoes and protists (single-celled organisms).

 

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David wading to collect samples - always that temptation to go a bit deeper than the length of the waders...

 

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Team photograph

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In February 2011, two botanists from the department, Dr Harald Schneider and Dr Cécile Gueidan, participated in a collecting trip in Northern Vietnam. The trip  aimed at enhancing NHM and Vietnamese collections in ferns, lichens and liverworts from this very species rich area of South-East Asia. It was organized by collaborating partners from the Vietnam National Museum of Nature in Hanoi by the botanists Mr Do Van Truong and Mrs Ngan Lu Thi. The team was also joined by Dr Hongmei Liu, who is a botanist from the Fairylake Botanical Garden in Shenzhen, China.

 

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After arrival, the team visited the Vietnam National Museum of Nature in Hanoi and studied fern specimens kept in the museum’s collection. They also met Prof. Pham Van Luc, the director of the Vietnam National Museum of Nature, and Harald Schneider and Cécile Gueidan presented their research to the Museum staff and students. Most of the three weeks were spent in different protected areas in the North of Vietnam: the Pa Co-Hang Kia Nature Reserve in the extreme West of the Hoa Binh province, the Bac Me Nature Reserve in the South-Eastern part of the Ha Giang province, the Na Hang Nature Reserve in the North of the Tuyen Quang province and the Ba Be National Park in the North- West of the Bac Kan province. Most of the sites visited included tropical forests at different stages of land use, which ranged from almost entirely deforested areas to few relatively untouched patches of primary forest.

 

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Left to right: Hongmei Liu, Harald Schneider, Don Van Truong, Ngan Lu Thi and two guides from the Ba Be National Park

 

 

This collecting trip followed a first visit to Vietnam by Harald Schneider in 2010 and had allowed completing previous collections of ferns from this area. For lichens, only few studies had been carried out in this country and rock substrates had almost not been explored. The lichen specimens collected during this fieldtrip will therefore contribute to the knowledge of the poorly studied lichen flora of Vietnam. In total, we collected 283 specimens of ferns (including at least two new records for Vietnam), 26 specimens of leafy liverworts, and about 400 specimens of lichens.

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Archaeopteryx - a bird?

Posted by John Jackson Aug 1, 2011

Archaeopteryx must be one of the most familar images associated with the origins and evolution of birds.  Famously, it was first described one hundred years ago in 1861 from a single feather in 150-million year old Jurasssic limestone from Solnhofen in Bavaria. 

 

NaturalHistoryMuseum_041333_IAblog.jpg


The first skeletal fossil of Archaeopteryx was found in 1861 and purchased by the British Museum (part of which later became the Natural History Museum) for £700 in 1862.  This specimen was described by the then Superintendent of the Museum's Natural History Departments, Richard Owen, in 1863.  A further nine fossils have been found since then and are found in various museums. Although the first fossil found was of a feather, it is not now certain that the feather was from the same species as the body fossils. When first found, Archaeopteryx was uniquely important in showing the connection between birds and other reptiles - but since  then, evidence from many other fossils has supported the scientific view  of the origins of birds.


These fossils have traditionally been seen as those of a very early bird at the very base of the current avian branch of the Tree of Life.  The birds emerged by the evolution and diversification of a group of reptiles in the late Jurassic period - just over 161 million years ago. From a current scientific viewpoint, the basal group of reptiles - the Paraves - split to form two groups: the Avialae (becoming birds over time); and the Deinonychosauria. 


However, a new paper in the journal Nature by Xing Xu et al. has involved examination of a newly discovered fossil species from this group, Xiaotingia, from China.  This organism was very similar to Archaeopteryx and the question arose of whether Archaeopteryx should be placed in the Avialae or the Deinonychosauria: which branch? Systematic scientific investigation of several Archaeopteryx fossils, Xiaotingia, and other fossils, suggests initially that Achaeopteryx does not fall into the same group as the birds - the Avialae. This involved examination of the NHM Archaeopteryx, illustrating the importance of collections as a continuing reference resource for science.


The research suggests that Archaeopteryx is not an ancestral bird in the Avialae, but should instead be seen as a member of the Deinonychosauria, along with Xiaotingia.  This finding will cause considerable controversy in science as results are scrutinised and discussed and further evidence amassed.  Future fossil findings will add further data that may add detail and support for different positions, but reference to the original fossils will continue to be essential.  One point of interest will be that the characteristic feathers and skeleton of Archaeopteryx show that this character combination may not have been restricted to birds alone, but seems to have been found in a wider group of reptiles.

 

Witmer L M Palaeontology: An icon knocked from its perch Nature 475, 458–459 (28 July 2011) doi:10.1038/475458a Published online 27 July 2011


Xing Xu,Hailu You,Kai Du & Fenglu Han An Archaeopteryx-like theropod from China and the origin of Avialae Nature 475, 465–470 (28 July 2011) doi:10.1038/nature10288 Published online 27 July 2011