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Science News

155 Posts authored by: John Jackson
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Denis Michez,  University of Mons, Belgium

 

Wednesday 2 April 11:00

 

Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)

 

Bees (Anthophila) are one of the major groups of angiosperm-pollinating insects and accordingly are widely studied in both basic and applied research, for which it is essential to have a clear understanding of their phylogeny, and evolutionary history. Direct evidence of bee evolutionary history has been hindered by a dearth of available fossils needed to determine the timing and tempo of their diversification, as well as episodes of extinction.

NaturalHistoryMuseum_PictureLibrary_015744_Comp-1 bee.jpgCopal from East Africa containing Apis mellifera

 

Here we assess the similarity of the forewing shape of bee fossils with extant and fossil taxa using geometric morphometrics analyses. Predictive discriminant analyses show that fossils share similar diagnostic forewing shapes with families like Apidae, Halictidae, Andrenidae and Melittidae. Their taxonomic assessments provide new information on the distribution and timing of particular bee groups like corbiculate groups, most notably the extension into North America of possible Eocene-Oligocene cooling-induced extinctions.

 

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

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Maarja Öpik,  Department of Botany, University of Tartu, Estonia


Wednesday 26 March 11:00   Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)


Arbuscular mycorrhizal fungi (AMF, Phylum Glomeromycota) are soil and root-dwelling, obligate plant root symbiotic organisms present in most terrestrial environments. Their occurrence and diversity have important roles in life, and in diversity and functioning of host plant communities. Therefore, understanding the taxonomic and functional diversity of AMF is the topic of increasing popularity. Their diversity patterns are described to address questions ranging from climate change and land use effects to understanding ecosystem succession and macroecological patterns.

 

Diversity of AMF is commonly measured using DNA sequences of nuclear ribosomal operon markers; the most frequently used one being the SSU rRNA gene. Total AMF molecular operational taxonomic unit (MOTU) richness of SSU rRNA gene sequences suggests at least twice as high number of species present as is currently known on the basis of morphotaxonomy.

 

These MOTUs have been organised into a common system of “virtual taxa” (VT) in a public database MaarjAM (http://maarjam.botany.ut.ee). VT are delimited as phylogenetically related clades of sequences of SSU rRNA gene at approximately species level. VT nomenclature provides comparability among data and consistent communication among scientists.Application of the VT nomenclature has allowed description of AMF diversity patterns from global to local scales.

 

In this talk, I will present evidence of global scale patterns of AMF diversity being related to biomes and climatic zones; and of local scale patterns related to host ecological groups, spatiotemporal processes and root- vs. soil-localising AMF growth strategies. I will conclude with highlighting the questions of urgent need to advance the understanding about this important group of organisms.

 

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

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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.

 

zjsem.jpg

 

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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Not so Scilly after all!

Posted by John Jackson Feb 28, 2014

Mark Spencer

Department of Life Sciences, NHM

 

Wednesday 5 March 11:00

Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)

 

The Isles of Scilly are a small archipelago of islands off the coast of Cornwall in SW Britain. Over the last few years I have led several teams of volunteers and, more recently, staff members on expeditions to collect material to enhance our UK collections. In 2013 this culminated in a cross-departmental project in partnership with the NHM’s Nature Live team and the Isles of Scilly Wildlife Trust. In this talk I will explore ideas around how field collecting can be linked to our public engagement activities as well as identify why the Isles of Scilly are a collections-based research worthy destination. And show some pretty pictures….

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Friday 28 Feb, 4.30pm, Neil Chalmers Seminar Room

 

Livestreamed on http://www.youtube.com/user/SciFriSeminars

 

 

Chemosynthesis-based communities through time: a 3.2 billion year history

 

Cris Little, University of Leeds

 

At the beginning of this seminar I will briefly review the ecology of modern chemosynthetic communities at hydrothermal vents, hydrocarbon (‘cold’) seeps and sunken dead whales (whale-falls) touching on biogeography and discussing evolutionary issues, including molecular divergence estimates for several major taxonomic groups.

 

little1.jpg

 

Then I will turn to the fossil record of these communities, which for vents goes back 3.25 billion years. I will show that vent and seep fossil assemblages have changed in taxonomic structure during the Phanerozoic, from brachiopod dominated communities in the Palaeozoic and early Mesozoic to mollusc (bivalve and gastropod) dominated communities from the later Mesozoic onwards. Some of the ecologically dominant taxa that have chemosymbiotic bacteria (e.g. vesicomyid clams and bathymodiolin mussels) are relative newcomers to vent and seep environments and were preceded by other, now extinct, bivalves that may (or may not) also have had symbionts.

 

Whale-fall communities from the Miocene are similar in structure to modern examples in the so-called sulfophilic stage, but older Oligocene and latest Eocene whale-fall communities lack some of the typical molluscs. This may be related to the small size of whales in their early evolutionary history. Prior to the Eocene whale-fall-like communities may have existed on sunken marine reptiles (e.g. turtles, ichthyosaurs and plesiosaurs), or even large fish carcasses.

 

 

About SciFri

 

SciFri is a cross-departmental science seminar series and social event run by the NHM Science Forum, held 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, publishing, media, fieldwork and science methods. If you have ideas for future speakers from any of these areas please contact the seminar organiser Adrian Glover, Life Sciences Department.

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Those people over fifty in the UK will remember the tremendous change to the landscape in many areas of the country as a result of the death of more than 25 million Elm trees from Dutch Elm Disease. 

 

There are fears now that we may see the same loss for Ash from Ash Dieback and Mark Spencer has been representing the NHM in government-organised stakeholder forums and summits as part of the UK response to this invasive alien disease.

 

Ash Dieback was first seen in the UK in early 2012 in imported nursery trees and in late 2012 in the wider environment in the east of England.  It's a disease caused by the fungal pathogen commonly known as chalara (Hymenoscyphus pseudoalbidus) that has had significant impacts on Ash trees across Europe over the past twenty years.

 

2013 saw significant development of policy, disease monitoring and raising public awareness and involvement. The UK Department for Food, Environment and Rural Affairs (Defra) convened a Tree Health and Plant Biosecurity Expert Taskforce (chaired by Professor Christopher Gilligan, an NHM Trustee) as part of the response to the outbreak of Ash dieback. The taskforce report recommended better prediction, monitoring and other measures to control the problem. One of the recommendations was for a UK Plant Health Risk Register which was launched on the 21 January 2014.

 

As a consequence of his work on plant health and the Risk Register in particular, Mark Spencer has been asked to contribute to a Defra-funded consultation on ‘Major drivers of emerging risks in plant health, in particular concerning native broad leaved trees in the UK’.

 

The Forestry Commission has been active in promoting public awareness and reporting of Chalara through its own website and receives data through web and smartphone tools such as Ashtag. NHM has been developing wider public participation with partner organisations through the OPAL Tree Health Survey that enables members of the public and schools to identify trees and tree health problems such as Ash Dieback with guides and Apps and to submit results as part of scientific research.

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The Natural Environment Research Council (NERC) has announced results for proposals from universities and partners for Doctoral Training Programmes. This replaces NERC's former system for allocating studentships directly to university departments.   The  purpose of this change is to ensure PhD  students will be equipped with a wider range of specific skills that will enhance  their employability in a wide variety of academic, commercial, media, and  government sectors and to ensure training is focused on NERCs strategic  priorities and/or priority skills needs.

 

The  announcement on 4 November covered 1,200 studentships that will be awarded over  the next five years: 240 PhD studentships per year. These will  be distributed over 15 successful DTPs with a total programme budget of £100  million.

 

The Museum is a hosting partner of four DTP proposals, as follows:

 

  • Great  Western 4 Plus (GW4+) DTP (28 studentships per year)
    • Lead - University of Bristol

    • Hosting and Training Partners - University of  Exeter, Cardiff University, University of Bath, The Natural History Museum,  British Antarctic Survey, British Geological Survey, Plymouth Marine  Laboratory, Met Office
  • Spitfire  DTP (15 studentships per year)
    • Lead - University of Southampton
    • Hosting and Training Partners - National  Oceanography Centre, The Natural History Museum, British Antarctic Survey, Centre for Ecology and Hydrology, Marine Biological Association, Plymouth Marine Laboratory, Sir Alister Hardy Foundation for Ocean Science, HR Wallingford
  • London DTP  (24 studentships per year)
    • Lead - University College London
    • Hosting and Training Partners - Birkbeck  University of London, Brunel University, King’s College London,  Queen Mary University of London, The  Natural History Museum, British Geological Survey,  Centre for Ecology and Hydrology, Met Office, Royal Botanic Gardens Kew,  Zoological Society  of London - Institute of Zoology
  • Science  and Solutions for a Changing Planet (SSCP) DTP (15 studentships per year)
    • Lead - Imperial College London (Grantham  Institute for Climate Change)
    • Hosting and Training Partners - The Natural History Museum, Met Office, British Geological Survey, Centre for Ecology and Hydrology, Royal  Botanic Gardens Kew, Zoological Society of London - Institute of Zoology


In addition to development and supervision of DTP-related project proposals, Museum staff will provide lectures, practicals, field trips, and other elements in professional development training courses. Museum staff have particular expertise in theprinciples and practice of taxonomy, collections, systematics and taxonomy of particular groups, presentation skills, communication of science to public audiences, scientific publishing and scientific media work.

 

Contacts:

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Research opportunities in Myanmar


Dr Celia Russell, Mimas, University of Manchester

 

Tuesday 3rd September - 4.00 pm - Mineralogy seminar room

After decades of isolation, universities in Myanmar (Burma) are gradually re-opening to the world, and the country is teeming with possibilities of research and teaching partnerships.  Myanmar is a country rich in natural resources with a unique geology and an exceptionally rich biodiversity.

Dr Celia Russell from the University of Manchester, who has recently returned from a scoping mission to the country, will be providing an overview of the areas in which Burmese universities are seeking to establish research partnerships.


With few university websites, email systems or bank accounts, the session will also give a brief overview of the processes, red tape and communication issues around working in Myanmar, as well as sources of help and support. This meeting also aims to create a network of contacts, to enable sharing of existing links and experiences and create an opportunity to discuss a way forward for improving museum engagement in Myanmar.


An invitation is extended to all colleagues who have an existing research interest in the country, or wish to find out more about developing a partnership. There are few financial resources available within Myanmar itself, but sources of international funding are available and the potential research rewards exceptional.

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A consortium led by Dr Rob Huxley, NHM, has been awarded a grant of €289,460.19 towards the development and testing of  a competency framework for natural history collections management staff in Europe. The  project is 75% funded by the EU  Leonardo da Vinci Programme, Transfer of Innovation (TOI) strand and runs for two years from 1 October 2013.

The project aims to create a system, based on standardised European competencies, to assist organisations identify the competencies required for individual roles. For individuals, the system will identify their current level of competency and their vocational and educational training needs.  TOIs, as the name clearly indicates, allow organizations to work with European partners to transfer and adapt innovative vocational education and training materials and methods. In this project we will transfer the uniquely comprehensive Collections Competency Framework developed by the NHM and in use since 2007. This system has demonstrated advantages with staff progression, consistency of approach and has proved a valuable tool in developing staff development and training needs. By mapping job requirements against the competency framework, staff are able to identify gaps in their knowledge and skills and use this information to identify their personal needs. 

This TOI  project will pilot a set of multi-language, standardised core competencies derived from the NHM framework that can be chosen and arrayed to suit the needs of museums of varying size, focus, culture and governance. To assist staff and trainers to meet their competency needs the project will also establish a curriculum of collections management training and development opportunities.   These common standards of competence will inform staff development,  recruitment and encourage mobility of staff across Europe and in a wider context will contribute to developing  a consistent level of best practice in collections management across the major collections based organisations with consequntg benefits to research and educational access.

The core partners in the project are: NHM, London; Royal Belgian Institute of Natural Sciences,  Brussels; Vriej Universiteit Amsterdam; Collections Trust, UK ; Museum fur Naturkunde, Berlin; The National Museum, Prague; Muséum National d'histoire Naturelle,  Paris.  Associated partners are: Naturalis Biodiversity Center, Leiden; Museo Nacional de Ciencias Naturales, Madrid; University of Florence Natural History Museum; Rathgen Research Laboratory Staatliche Museen zu Berlin; HTW Berlin University of Applied Sciences.

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We have around 80 million items in the Museum collection.  This makes us one of the world's greatest natural history collections and there is a huge amount of expertise, organisation, investment and thinking goes into caring for this resource and making it available to scientists and to many other users, including the general public in the UK and worldwide.

 

A basic characteristic of any item in the collection is that we know what it is, where it comes from and when it was collected.  Without this information, its value for science is much reduced.  However, because collecting has been in progress since the 17th Century, most of the information that accompanies the specimens is written on paper: on labels or in books, record cards and registers.  A scientist wanting to know whether we have particular items or to find out more information would need to talk to NHM curators or visit us to look at the information resources first-hand.

 

But in the last ten years in particular, we have been developing electronic databases of the collections.  It's a major task with a lot of experimentation with the best techniques and tools - how do we transfer tens of millions of information points from paper to databases to enable online searches and research resources?  We've got basic information for around 400,000 specimens on our main database at the moment but we need to move faster, and we are trying out different approaches.

 


globe.JPG

a plot of 400,000 specimen records that have been databased, showing origins

 

A new initiative is to involve members of the public in copying information from the registers online - crowdsourcing.  We are doing this at the moment for our bird collections and would like as many people as possible to join us in this effort - we'll then be able to move more quickly to online information on which bird specimens we have, with information on their place of origin and dates.  Sometimes this information can be used to do research on where bird species once occured but where they have now disappeared because of habitat loss or other factors.

 

reg.JPG

 

a snapshot of one of the register pages

 

Have a look at the online ornithology registers on the Notes from Nature site and have a try - you can attempt one-off transcriptions, or register and create an account that allows you to track your contribution to this effort.

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Many species and larger taxonomic groups, especially invertebrates, have been little studied in terms of their patterns of geographical distribution - biogeography - and even basic information, inventories and assessments are missing.  A key reason for this is that collecting and sampling has been too limited and too uneven: there are simply no good baseline data on distributions.

 

Ian Kitching of the NHM Life Sciences Department, with colleagues from the University of Basel, Switzerland, and Yale University, USA, set out to establish why inventories for the hawkmoths of Sub-Saharan Africa are incomplete, considering human geographical and associated environmental factors.

 

xanthopan-morganii-praedicta-madagascan-sphinx-moth-_105466_1.jpg
Xanthopan morganii praedicta - a hawkmoth found in Madagascar and East Africa

 

They used a database of hawkmoth distribution records to estimate species richness across 200 x 200 km map grid cells and then used mathematical models predict species richness and  map region-wide diversity patterns. Next, they estimated cell-wide inventory completeness related to human geographical factors.

 

They found that the observed patterns of hawkmoth species richness are strongly determined by the number of available records in grid cells. Vegetation type is an important factor in estimated total richness, together with heat, energy availability and topography. Their model identified three centres of diversity: Cameroon coastal mountains, and the northern and southern East African mountain areas. Species richness is still under-recorded in the western Congo Basin and in southern Tanzania/Mozambique.

 

What does this mean?  It means that sampling (and therefore our knowledge) of biodiversity is heavily biased.  We have good data and information where there is higher population density; for more accessible and less remote areas; for protected areas and for certain areas where there was collecting in colonial periods.  If it is easy to get to, not too difficult to access, there are more people around and there have been longer histories of collecting: we have better knowledge. 

 

This is important in how we understand biodiversity and in how we make decisions with our knowledge to protect forests or other areas.  But this study means that we can take account of data gaps if we are looking at larger scale patterns of diversity.  It shows that baselines for broad diversity patterns can be developed using models and what data there is available.  We can identify the "known unknowns" in terms of information gaps in part by looking at human geographical features - the models can help set priorities for future exploration and collection as well as informing our understanding of biodiveristy.


Ballesteros-Mejia, L., Kitching, I.J., Jetz, W., Nagel, P. & Beck, J. 2013. Mapping the biodiversity of tropical insects: species richness and inventory completeness of African sphingid moths. Global Ecology & Biogeography 22: 586-595. (doi: 10.1111/geb.12039)

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A natural geographical range for a particular species is familiar  - organisms have evolved to flourish in environments with particular combinations of temperature, rainfall, water and food availability, competition and many other factors.  These are often described in terms of ecosystems, habitats or ecological niches.

 

However, species do appear in new places that can be remote from their original range.  Some populations expand into new areas.  The Collared Dove in Europe is a good example - it was first recorded regularly in the Balkans in the early 20th Century - having extended its range from Asia Minor - and spread across Europe gradually, reaching the UK in the 1950s. It is now a very familiar bird in the UK. 

 

A relatively recent arrival to the UK is the Tree Bumblebee, Bombus hypnorum, which is native and widespread on the European mainland.  It was first recorded in the UK in 2001 and is now widespread in England, particularly in the south.

 


B hypnorum NaturalHistoryMuseum_PictureLibrary_055983_Comp.jpg

Bombus hypnorum in the NHM wildlife garden

 

Other species are introduced to new areas deliberately or accidentally by human action.  Deliberate introductions include Grey Squirrels and Canada Geese that were introduced from North America to the UK as ornamental animals, Japanese Knotweed as a garden plant and the Harlequin Ladybird to control pest insects - most have had unanticipated adverse impacts to a greater or lesser degree.  Accidental introduction of the fungal Dutch Elm Disease in timber led to the death of around 20 million Elm trees in the 1970s, transforming the UK landscape.  Recent concern has focused on Ash Dieback disease - Chalara - which is thought to have been introduced accidentally to the UK in 2012 and which has spread across southern England. 

 

Some introduced species seem to have little impact, but many are of concern because they increase rapidly in the absence of normal controls such as predators, displacing native species or because they have economic impacts: these species of concern are often described as invasive.  Governments therefore support research, monitoring and control for a wide range of invasive species.


Accurate knowledge and identification is essential if control is to be effective and the NHM's strengths in species identification and training have been important in supporting policy.  The NHM became a founder partner of the international Global Invasive Alien Species Information Partnership last year by signing an MOC with the Convention on Biological Diversity. Chris Lyal is chair of the Partnership’s Interim Steering Committee and administers its Information Gateway, developed with the NHM Scratchpad Team.

 

In May 2013 Chris organised and hosted an international technical workshop for the partnership with EU funds obtained from the CBD, with 18 participants from key organisations around the world. The Workshop developed plans for the informatics infrastructure necessary to better access and deliver information, and advised on a range of Partnership activities. Chris also received EU funds through the CBD for populating the Information Gateway.  

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Tom Richards from the Museum's Life Science department is an author on a paper in Nature that explores the genome of one of the most abundant species of planktonic plant - the coccolithophore Emiliania huxleyi.  Coccolithophores occur in great numbers in the ocean: the chalk cliffs at Dover are made up of the remains of their calcium carbonate skeletons.

 

The World's oceans are tremendously complex.  Currents move over thousands of kilometres, some descending as they are cooled by weather systems, or mixing at the surface with fresh waters, sediments and nutrients from continental rivers.  Life is immensely diverse, ranging from corals to the deep-sea vent faunas.  The highest biomass of life is in the shallow seas near to land, but the open ocean contains a constantly shifting system of tiny planktonic organisms ranging from bacteria to single-celled plants to grazing zooplankton and their predators. 

 

These planktonic ecosystems change with currents, seasons, nutrient availability and predation. Their growth, population explosions, deaths and decline interact with the planet's cycling of carbon and other nutrients.  These interactions are important in understanding ocean productivity and climate: there are links to carbon dioxide fluctuation, for example, as the plants absorb it during growth and release some at death.  Despite the tiny size of the organisms, their huge numbers over two-thirds of the planet's surface means that their role in planetary systems is very significant.

 

E. huxleyi experiences huge population explosions in the open ocean - planktonic blooms. Some species of phytoplankton bloom under very particular conditions of temperature and nutrient availability, but E. huxleyi thrives in a wide range of conditions, occuring from the warm waters of the equator to polar regions.

 

NaturalHistoryMuseum_PictureLibrary_033355_Comp.jpgEmiliania huxleyi, showing the distinctive calcium carbonate plates that cover its exterior. 

These may have important protective and light-reflecting qualities for the organism.

 

The paper finds that E. huxleyi strains from different areas share a core genome - this gives them a robust abilty to resist the inhibiting and damaging effects of intense sunlight, together with genes that allow effective growth in low phosphorus conditions.  There are genetic differences between the strains that lead to distinct abilities to thrive in different nitrogen, ammonia and metal conditions.  It seems that this, and other characteristics, give E. huxleyi the ability to bloom in very different oceanic environments - it is described as a species complex because of its genetic diversity.

 

This work will enable scientists to understand better the responses and influences of this very widespread species, and to investigate the complex processes and systems of the ocean that determine productivity and influence climate change.

 

Read, B.A. et al. (2013) Pan genome of the phytoplankton Emiliania underpins its global distribution. Nature doi:10.1038/nature12221

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On the nature & causes of volcanism in the Galápagos archipelago

 

Tuesday 21st May - 4.00 pm - Mineralogy seminar room

 

Dr Sally A Gibson, Department of Earth Sciences, University of Cambridge, UK. sally@esc.cam.ac.uk

 

Diversity appears to be key to understanding natural phenomena in the Galápagos archipelago. Whilst most associate this with the unusual creatures that inhabit the islands it is also true of their volcanic nature.

Historical perspective: The volcanic nature of Galápagos was based on reports of pirates, buccaneers and naval admirals until 1835, when Charles Darwin visited the archipelago during the Beagle voyage. Although widely regarded as a zoologist, Darwin was first and foremost a geologist and especially interested in the formation of volcanic islands. Whilst in Galápagos, most of his time was spent on James Island (now known as Santiago) and here he made a crucial observation regarding the occurrence of different volcanic rock types; he realised that confinement of low-density trachytes to elevated parts and higher-density basalts to lower slopes of the same volcano meant that different types of magma could form in ‘the body of a volcanic mountain’ by sinking of crystals. In this regard he was the first scientist to link the diversity of volcanic rock types to what we now refer to as crystal settling. Darwin’s theory of crystal sinking was published in 1844 but not widely accepted at the time.

 

21st Century importance: The Galápagos archipelago is a natural laboratory for Earth Scientists and provides a unique opportunity to test models of mantle melting. It is one of the world’s most volcanically active regions with eruptions of predominantly basaltic lavas occurring every 3 to 5 years. Galápagos is located above a mantle plume and adjacent to an oceanic spreading centre. Whilst the greatest volumes of melt occur in the west of the archipelago, close to the postulated axis of the plume, volcanism is widespread. There are no age-progressive linear relationships between activity and distance from the location of the present-day hotspot and no temporal variation in magma type as there is for example at Hawaii. The large geochemical dataset for recently erupted basalts and high-resolution seismic database allow greater constraints to be imposed on the causes of volcanism than for any other archipelago. Melt generation occurs both in the region of active mantle upwelling, which has a radius of ~100 km, and also where plume mantle is being dispersed laterally towards the adjacent spreading centre. The composition of erupted basalts is closely linked to the thickness of the underlying lithosphere: numerical modelling of geochemical and geophysical datasets has revealed that this is relatively thin (45 km) beneath the NE of the archipelago and allows the generation of tholeiitic basalts. Above the current zone of active plume upwelling the lithosphere is thicker (60 km) such that the amount of melting is lower and alkali basalts are generated. Isla Santiago is located in central Galápagos above the margin of the zone of active upwelling and also on the edge of the zone of thin lithosphere. The island is unique in that it has experienced recent eruptions of basaltic melts with extremely varied major- and trace-element and also isotopic compositions. This diversity is a manifestation of both complex physical processes and compositional variations in the underlying mantle plume.


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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The great majority of the more than 400 families of snails are found only in the sea, while about 5% of them are exclusively freshwater. Very few snail groups are common in both environments and just three marine families have rare freshwater members.

 

One of these is the Littorinidae (periwinkles), familiar from rocky shores. In the nineteenth century three freshwater periwinkle species (genus Cremnoconchus) were discovered in the mountainous Western Ghats of India, living in fast-flowing streams at altitudes between 300 and 1400 m. These have not been studied for over 100 years.

 

Cremnoconchus.JPGFigure from the original description of Cremnoconchus (images 1-7) Image courtesy of Biodiversity Heritage Library. http://www.biodiversitylibrary.org

 

In a collaboration with scientists from the NHM's partner organisation the Ashoka Trust for Research in Ecology and the Environment (ATREE), Bangalore, David Reid revisited the type localities of the three known species to collect new specimens. (The type locality is the place in which the reference specimen was found that was originally used to describe and name the species.) These were studied to find out more about the snails and allowed the relationships between the species to be investigagted in more detail and revised.  There are distinctive differences between the species particularly in terms of their radula (the rasping tongue of snails), their reproductive systems and the calcified operculum (the disc that fits into the shell opening when the snail retreats into the shell, providing additional protection from predators and desiccation).

 

In addition, an unknown radiation of six new Cremnoconchus species was discovered in the central Western Ghats, 500 km south of the previously known range where David and his collaborators looked at the known species.

 

Cremnoconchus is interesting in evolutionary terms: the current evidence suggests that its closest living relatives are marine snails found only in New Zealand and Australia, suggesting that the ancestral population was split by the breakup of the ancient continent Gondwana during the Cretaceous, between 145 and 65 million years ago.  However, more evidence and DNA studies would be needed to confirm this hypothesis.


Each of the six new species was restricted to a single stream system on the steep western escarpment of the Deccan Plateau, with limited overlap in distribution in two places.  This suggests that populations of ancestral species were isolated by waterfalls or other features allowing evolutionary divergence over time The habitat of these snails is fragile, being very limited in scale and threatened by tourism, road construction and domestic pollution: all the species are judged to be endangered.

 

Reid, D.G., Aravind, N.A. & Madhyastha, N.A. (2013) A unique radiation of marine littorinid snails in the freshwater streams of the Western Ghats of India: the genus Cremnoconchus W.T. Blanford, 1869 (Gastropoda: Littorinidae). Zoological  Journal of the Linnean Society. 167: 93-135.
DOI: 10.1111/j.1096-3642.2012.00875.x

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