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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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Darwin's Corals in Science News

Posted by John Jackson Jun 27, 2011

Brian Rosen (Zoology) and Jill Darrell (Palaeontology) have just published a paper on Darwin’s coral specimen collections and specimen lists. Darwin examined coral reefs in detail during the voyage of HMS Beagle, describing the different types of reef and using this information to write one of his early scientific works The Structure and Distribution of Coral Reefs

 

They were invited to present a talk on this subject at a conference on Darwin’s work at the Universita G. d’Annunzio, Chieti-Pescara, in November 2009. The paper deals with the only known Darwin geological collection in the Museum that comprises 29 coral reef specimens (held in Zoology), almost all from Cocos (Keeling) atoll in the Indian Ocean and accompanied by a little known and hitherto enigmatic Coral Reef Specimen List (holograph held in the NHM Library). Darwin mentions his visit to Keeling and interest in corals in a letter to his sister, sent from Mauritius.

 

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Darwin distinguished three primary types of reef: atolls, barrier reefs and fringing reefs, and used his own observations and those from FitzRoy's surveys to explain what he thought were the reasons for the existence of atolls - including Keeling, which he examined in detail.  Darwin noticed that reef-building corals did not grow below a certain depth of water, but that atolls isolated from other rocky islands were reasonably common.  He rejected the idea that gradual sediment buildup had provided foundations, and said that the idea of so many isolated sea-mounts of the right depth in the middle ocean for coral growth could be rejected.  He argued that rocky islands had sunk gradually below the surface, leaving their original coral reefs to keep the same level as the surface of the sea.  Darwin thought that earthquakes might be connected with the sinking islands - he did not know then what we know about plate tectonics, but had developed a keen interest in geological uplift and subsidence in South America on an earlier part of the voyage.

 

Brian and Jill offer for the first time a plausible explanation of the true origin and purpose of this list and set of specimens.  The specimens are unusual, if not unique, in being a small exhibit prepared by Darwin himself, at or before the time he donated them. The most likely occasion for which Darwin prepared his exhibit was that of his first presentation of his famous subsidence theory of coral reefs to the Geological Society of London on May 31st 1837.

 

Rosen B. R & Darrell, J. 2011. A generalized historical trajectory for Charles Darwin’s specimen collections, with a case study of his coral reef specimen list in the Natural History Museum, London. In:  Stoppa, Francesco & Veraldi, Roberto, Eds., Darwin tra scienza, storia e società. 150° anniversario della publicazione di Origine delle Specie [= Darwin in science, history and society. 150th anniversary of the Origin of Species.]  Edizioni Universitairie Romane, Roma, pp.133-198.

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Charles Darwin is best known as an evolutionary biologist but he also had significant success as a geologist.  His first three scientific books after his account of the voyage of the Beagle explored the geology of coral reefs, volcanic islands and South America: The Structure and Distribution of Coral Reefs (1842); Geological Observations of Volcanic Islands (1844); and Geological Observations on South  America (1846).

Dr Brian Rosen, a Scientific Associate in the NHM Department of Zoology, gave an invited public lecture, hosted by the Bermuda Institute of Ocean Sciences (BIOS) in their ‘Distinguished Lecture Series’ in November 2010, entitled ‘Red or Blue? Darwin's Bermuda Dilemma and his Enduring Subsidence Theory of Coral Reefs’, in which he discussed Darwin's ideas and conclusions.

Darwin's subsidence theory of the origin of coral atolls was based on the idea that the world's ocean floors as a whole were subsiding, and that atolls had developed as coral growth kept pace with sea level on the sinking foundations of former volcanoes. The sheer scale and simplicity of Darwin's idea was reflected in his famous coral reef map, on which he shaded atolls and most other oceanic reefs in blue (inferring subsidence), and most reefs elsewhere in red (inferring uplift or stability).

Darwin's theory was initially acclaimed but over time it seemed too revolutionary for many - alternative ideas such as sea level changes were preferred.  However, by the mid twentieth century, it became clear that the reef deposits of most atolls did indeed extend hundreds of metres beneath their surfaces - far deeper than can be explained by glacial sea level changes alone. 

We know now that atolls do form because islands sink gradually as a  consequence of tectonic plate movement.  While Darwin was correct about  the subsidence, tectonic plate movement and sinking as a reason was not proposed until 1912, althougth this was hotly contested until scientific explanation in the 1950s and 1960s.

Although Darwin did not visit Bermuda, he included it in his coral reef book. Bermuda's reefs - being essentially ring-like in arrangement, and with a central lagoon - are atoll-like, but for other reasons Darwin was equivocal about whether it was a true atoll, so he left it uncoloured on his reef map. In his lecture Brian Rosen attempted to resolve Darwin's dilemma, based on the fact that the sea levels at Bermuda have fluctuated over time.

 


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By Elena Lo Giudice, University of Kiel

 

This is Elena, a PhD student at the University of Kiel, in Germany. I’m an oceanographer so this is my first time on land and I never thought that the life of a geologist could be so exciting.

 

Our adventure started early in the morning trying to communicate with our driver, a very nice, patient and always-smiling guy. After a couple of misunderstandings we arrived at the outcrop and we started the initial investigation of the area. Our curiosity about a missing part of the rock succession drove us at first to the playground of a school, which was built in the middle of the section. Here we were accepted as rockstars - everybody wanted a picture of us - and then we reached the base of the outcrop, a very important point for our work. We were working on the edge of a mining area - there are lots of coal mines here. We will work on mined outcrops higher up in the section later this week but first we need to have health and safety training so we can be safe around the mining roads.

 


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Nathan and me with students at the local school

 

Our work today consisted of logging the outcrop, for instance defining the different rocks and geological structures present in the strata – from the base to the top - and measuring them. We make this information into a diagram (a log) so that other people on our trip can use them when they want to collect from the section. This way they will know where their fossil or rock samples came from and when we work out the ages and palaeoenvironments of the sections, they can relate that information back to the fossil faunas and floras they have identified and have more information on how they lived.

 

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Layers of clay, silt and sandstone at the Stadion Section near Samarinda

 

So, after this amazing day, I came back to the hotel with our driver’s smile impressed in my mind, a lot of pictures with the school guys and, of course, 80m of logged section, what can I ask more for just a single day?

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By Simone Arragoni, University of Granada, Spain

 

Indonesia… Just the sound of this word is enough to excite every geologist’s fantasy!! And that’s the place where we are right now!

 

Here the geology is something living, not just strange and boring words on a book: Indonesia is the hot and restless daughter of the convergence between the Indo-Pacific and Australian plates, animated by earthquakes, tsunamis, giant slides and….volcanoes, of course!!

 

 

We are now in Bandung, 140 km east of Jakarta, close to the Tangkuban Perahu Volcano (the “overturned boat-shaped” volcano), so we have enjoyed a “wet” tour in the lush rainforest which covers the flanks of the mountain, reaching a small crater with steam and boiling water springs. There you can even cook an egg and eat it in the foggy atmosphere created by the hot steams and the showery rains.

 

 

But the best is yet to come… through a slippery and narrow “natural staircase” we eventually reach the top of the volcano and have a look inside the main crater. And there you do feel that the mountain is alive, blowing its white fumes and quietly sleeping before the next eruption…Towards the east endless and mysterious mountains form the backbone of Java, while thousands meters below your feet the Australian plate is being pushed northwards and downwards in the mantle. The emotion is too strong (and the humidity too!), so we have to go away and eat something.

 

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The Tangkuban Perahu Volcano

 

We go down to Lembang, stopping at a typical Indonesian restaurant, where you can eat the famous ayam goreng (fried chicken). This is the real “Indonesian experience”, eating strange and spicy things and drinking hot tea and mango juice while the rain is hitting the roof.

 

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Javanese ayam goreng

 

The best conclusion for such a nice day would be a crazy ride on a rollercoaster-like road, packed up in a small van that will carry us to the hotel and the desired hot shower.

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Hello, over the next couple of months me and other scientists from the Natural History Museum are going to tell you about our field trip to Indonesia. We're going there to look at fossil tropical marine creatures from 20 million years ago and we will try to work out how they lived and how environmental change might have effected them.

 

At the moment we are getting our equipment together, having our injections, applying for visas and buying trousers-for-explorers (the ones that turn into shorts - yikes!). It's all quite exciting and we hope we'll be ready in time to fly out ion the 18th September.

 

We'll fly via Singapore to Jakarta in Java and then spend a week learning about stratigraphy in Bandung, just south of Jakarta. This is a teaching trip for Marie Curie Early Stage Researchers, so I'm looking forward to learning with them. Stratigraphy, for example, is the study of when and how rocks were laid down and what you can say about past environments by studying them.

 

After Java we'll fly to Balikpapan, which is a city in Kalimantan, western Borneo. From there we will travel north to Samarinda and start our field work. As far as I know, this will involve travelling to wherever rocks of the right age are exposed and looking to see what they contain, like corals or molluscs.

 

We will be posting pictures, video and text to this page throughout our trip, so log in to Nature Plus to hear the news of our adventures!

 

Meet the Natural History Museum explorers:

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            Dr Ken Johnson                                      Dr Jeremy Young                     Dr Jon Todd

           Corals researcher                                Microfossils researcher          Molluscs researcher

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Miss Nadia Santodomingo      Miss Emanuela Di Martino         Dr Lil Stevens

      Corals researcher                    Bryozoans researcher       Curator and palaeobotanist

 

The Mission:

We will work with people from other European and Indonesian institutions looking at how changes in the environment have affected coral reefs and shallow tropical marine ecosystems such as mangroves and seagrasses. This area has been a marine diversity hotspot for the last 20 million years and we want to look at the corals, molluscs, bryozoans, algae, and microfossils to understand how these organisms have interacted, evolved and adapted over that time. We will also study the dynamic geology of the area and the effects of ocean currents that flow from the Indian Ocean to the Pacific Ocean. Our discoveries will help us to understand why tropical marine ecosystems host a high biodiversity,and will be used to address issues associated with human disturbance and global climate change.

 

If you would like to read more about the project, go to the Indo-Pacific Ancient Ecosystems Group