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6 Posts tagged with the biogeography tag
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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.

 

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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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Life Sciences Seminar


Inferring the diversification of land plants at and in the shadow of the Roof of the World

 

Harald Schneider

Plants, Dept. of Life Sciences, NHM

 

Wednesday 12 of December 11:00
Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)


Orogenic events in earth history, e.g. mountain formation, have made a profound impact on the assembly of biological diversity. For example, recent studies of the biodiversity of South America recovered strong evidence that the Cenozoic rise of the Andeans triggered the rapid diversification of many lineages of vascular plants.

 

However, relatively little attention has been given to the effect of the rise of the Himalaya on plant diversity. The rise of this mountain chains were triggered by the collision of the Indian tectonic plate with the Eurasian continent 70 million years ago but major uplifts date back to more recent times. Especially the rather recent formation of the Qinghai-Tibetan plateau, around 3-4 million years ago, had a considerable impact on the monsoon climates in South East Asia. Thus the rise of this plateau affected not only the evolution of plants adapted to the alpine conditions at the high altitudes of the Himalaya but also the expansion of xeric habitats in central Asia and the enhanced monsoons affecting South East Asia and South Asia.

 

The hypothesis of the impact of the rise of the Himalaya on plant diversity in South East Asia is studied employing mainly phylogenetic approaches that incorporate divergence time estimates, ancestral area reconstruction, inference of niche evolution, and estimates of diversification rates. The analyses also incorporate evidence from micro-paleontological research.

 

Comparative assessment of the existing and newly generated phylogenetic hypotheses for a wide range of angiosperms and ferns recovered evidence supporting the hypothesis of a substantial impact of the rise of the Qinghai-Tibetan plateau on the assembly of lineage diversity. This result is consistent with palaeoclimate reconstructions that are based on pollen and spore record. In comparison, the recovered patterns indicate the involvement of different processes in response to the Cenozoic mountain formations in South America and South East Asia.

 

The presentation summarises research that was carried out during my time as a senior visiting professor of the Chinese Academy of Sciences. Besides the presentation of the results of the research, I will also touch on issues related to the current research conditions in China.

 

Harald Schneider

 

 

 

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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Ralf Britz and collaborators from the Conservation Research Group from St Albert's College, Kochi, Kerala have published a series of papers describing three new fish species from South India.

 

Pristolepis rubripinnis, Dario urops and Pangio ammophila were discovered during the January 2012 NHM-funded visit of Dr Ralf Britz to Kochi, to work with Dr Rajeev Raghavan. Historical specimens of the fish collection in the Natural History Museum collected by Sir Francis Day in the 1860s and 70s played an important role in the resolution of taxonomic and nomenclatural issues before the species could be described.

 

This series of papers highlights our incomplete knowledge of one of the most important biodiversity hotspots in Asia, the Western Ghats, a mountain range along the west coast of Peninsular India. Both Pristolepis rubripinnis and Dario urops are of particular interest in that closely related species are found in north-eastern India - it is not clear how this distribution arose because there are no river connections between the two areas that would have allowed ancestral populations to separate, migrate and diverge into different species. 


Britz, R., Kumar, K. & Baby, F. (2012). Pristolepis rubripinnis, a new species of fish from southern India (Teleostei: Percomorpha: Pristolepididae). Zootaxa, 3345: 59-68.

Britz, R., Ali, A. & Philip, S. (2012). Dario urops, a new species of badid fish from the Western Ghats, southern India (Teleostei: Percomorpha: Badidae). Zootaxa, 3348: 63-68.

Britz, R., Ali, A. & R. Raghavan. (2012). Pangio ammophila, a new species of eel-loach from Karnataka, southern India (Teleostei: Cypriniformes: Cobitidae). Ichthyological Exploration of Freshwaters, 23: 45-50.

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Tropical periwinkles

Posted by John Jackson Nov 29, 2011

David Reid (Zoology) has published the fourth and final monograph of the worldwide tropical periwinkle genus Echinolittorina which concludes a taxonomic review of all 60 species of this littoral gastropod mollusc.

 

This completes a 20-year project, which has required  collection of anatomical and molecular samples from across the globe,  study of all major museum collections and a 3-year NERC-funded molecular  programme (by PDRA Suzanne Williams, now also a Researcher in Zoology).  The recognized species diversity has been increased by about 50% and 14  new species have been described.

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A scanning electron micrograph of a portion (3 tooth rows from a lotal length of 5 mm) of the long radula ribbon of Echinolittorina placida.

 

 

As a result the group is now among the most comprehensively known of all marine invertebrates, with taxonomy, morphology, development, distribution and molecular phylogeny all described in detail. It has become a model system for the study of the evolution of tropical marine invertebrates in shallow water, and has been used, for example, to demonstrate the prevalence of allopatric speciation (speciation following geographical separation of populations), the Miocene origin of many extant species, the influence of tectonic activity on diversification, and evolution of mating signals by reinforcement.

 

More information on an example of the group, Echinolittorina placida, is found on the NHM species of the day pages.


Reid, D.G. (2011) The genus Echinolittorina Habe, 1956 (Gastropoda: Littorinidae) in the eastern Atlantic Ocean and Mediterranean Sea. Zootaxa 2974 1–65

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How do new species form?  One key process is by genetic divergence following geographical isolation – allopatric speciation.  This can happen when different populations of a single species are separated, cease to have contact over time and no longer interbreed.  This separation, divergence and formation of new species will often be attributed to changes in genetic makeup as a result of adaptation to different environments or ecosystems, or simply to accumulated genetic changes - genetic drift.

When it's difficult for individuals from the population to cross geographical barriers, it's possible to explain how isolation of populations occurs, and therefore why speciation has happened. An example would be the different but related species found on islands separated from the mainland, where a few individuals managed to cross the water barrier and form a new population that eventually became a distinct new species.  Charles Darwin collected specimens of mockingbirds on the Galapagos, for example, that are related to mainland species but which have diverged from the parent population to become a separate species, living in a new and different environment.

In the sea, however, many animals have pelagic larvae – free-floating planktonic forms - that can be carried for many hundreds of kilometres in currents, even though the adults have limited mobility on the sea bed.  This pelagic mobility means that closely related species from different places are potentially connected over distances of 1,000 km or more, so it is unclear how allopatric speciation is achieved – the populations appear to be capable of connection in geographical terms.

Zoology PhD student Martine Claremont, together with her Museum supervisors Drs Suzanne Williams and David Reid, and university supervisor Professor Tim Barraclough, sampled populations of the intertidal muricid gastropod genus Stramonita (a marine snail) throughout the Atlantic Ocean and used statistical analysis of DNA sequences to identify the number of distinct species, their distributions and relationships.

 

For species in which the larvae spend only a short time in the plankton, it is possible for populations to be clearly isolated geographically by currents, island chains or other factors such as the immense flow of fresh water flowing from the mouth of the Amazon. However, Stramonita spends 2-3 months as a planktonic larval form, theoretically permitting genetic contact across the entire ocean basin, which might lead to expectations that a single population would be found around the Atlantic. 

 

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Stramonita brasiliensis, the new species described in the work (E, Plymouth, Tobago, BMNH acc. no. 2341; F, holotype, Sao Paulo, Brazil, BMNH 20100324)


However, Martine and her supervisors found five distinct species in the Atlantic (one of which is described as new).  They suggest that this speciation might be attributed in part to past changes or interruptions in ocean currents, preventing free circulation and isolating populations for sufficient time to enable speciation.  Other factors that seem to be of importance are the ancient separation of the Caribbean and Gulf of Mexico and the development of ecological specialization.

 

Claremont, M., Williams, S.T., Barraclough, T.G., Reid, D.G. (2011) The geographic scale of speciation in a marine snail with high dispersal potential. Journal of Biogeography, 38: 1016–1032.

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Alfred Russel Wallace stands with Charles Darwin as an influential and innovative thinker on evolution.  Before the publication of Darwin's great work The Origin of Species in 1859, Wallace and Darwin were jointly credited with developing the key idea of natural selection, presented in a paper from them both to the Linnean Society in 1858.


Wallace's ideas had their foundations in his collecting experience in natural history: first in South America; and second in what is now Malaysia and Indonesia.  In particular, he was interested in the geographical distribution of species and how this related to evolution: what is now thought of as biogeography.

 

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The Museum has just purchased an album of sketches, watercolours and photographs belonging to Wallace from his family.  This is being added to a large collection in the NHM of Alfred Russel Wallace material: letters, notes, drawings and other papers. The collection is the second largest single depository of letter to and from Wallace, the British Library having the largest. The majority of the collection held in the NHM Library was purchased in 2002 from the Wallace family. Since then the family has presented to the Museum additional material, including more letters, papers and a few legal documents.

 

A project is now being led by George Beccaloni and Judith Magee to digitise all letters - not just the NHM collection - and make them available on-line with funding from the Mellon Foundation. The project employs one full time archivist and started in October 2010 to run for three years, culminating in 2013, the centenary of Wallace's death, and will be an important resource for historians of science.