I noticed today that though I haven't been an active blogger for over three years, the posts on this site still receive a lot of traffic. So if you would like to keep up with me in an abbreviated format, you can follow my twitter feed at SardaSahney.
Word clouds are a simple visualization tool used to display text. Words that appear more frequently in the source text greater prominence in the cloud. This is a word cloud created for Fish Feet.
Word clouds can be easily creating using online tools such as Wordle which allows you to make clouds from text or URLs with different fonts, layouts, and color schemes.
A quick blurb about a paper published in Geology this week by myself and colleagues, Michael Benton of the University of Bristol and Howard Falcon-Lang of Royal Holloway, University of London.
300 million years ago in the Carboniferous, the Continent of Euramerica (Europe and North America) lay over the equator and steamy tropical rainforests supports a great abundance of life. The primary vertebrates were amphibians, overshadowing recently evolved reptiles.
As the climate changed and became drier, rainforests fragmented, forming isolated 'islands' of forest. The changing climate, specifically the loss of humidity was bad for amphibians since they are tied to waterside habitats. However, reptiles, which have specific features allowing them to live in drier conditions began to dominate communities. Additionally, the fragmented nature of the landscape created endemism, that is unique populations of reptiles which increased their diversity.
Changes in climate and environment through slow earth process gives animals time to adjust and thrive in a new environment, shifting balances and even increasing diversity, but the rapid changes in our environment driven by human impact must be regarded with great caution since animals are often driven to endangerment and extinction before they have a chance to adjust to the change in conditions.
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What a week! We hadn't expected for the publicity on our paper in Biology Letters to be quite so extensive and controversial. And we certainly hadn't intended to be cast opposite to Darwin.
On the one hand we have had some unfortunate exaggerations, most notably the Huffington Post which writes Darwin May Have Been WRONG (Seriously does the editor think putting it in all caps makes it true??!!!?)
But on the positive end we have had some more fair minded reporting of the research, a few examples:
Sahney, S., Benton, M.J. and Paul Ferry 2010. Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land. Biology Letters 6:544-547.
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Published in Biology Letters today by myself, Michael Benton and Paul Ferry at the University of Bristol. Also an article at the BBC.
New research suggests that biodiversity is closely tied to the niches animals occupy, and the rich biodiversity we see on Earth today has grown out of expansion, not competition. Darwin cited competition among animals, coined ‘survival of the fittest’, as a driver of evolution in his book, On the Origin of Species; since then competition has been considered key to having grown Earth’s biodiversity. But while competition has been observed on a small scale, (eg. between species), there is little evidence of competition guiding large-scale shifts in biodiversity, such as the dominance of mammals and birds over reptiles and amphibians in today’s world. Our new research supports the idea that animals diversified by expanding into empty ecological roles rather than by direct competition with each other.
When vertebrates moved onto land millions of years ago, they filled empty niches further away from the water, and then they continued to invade new habitats evolved by other organisms such as forests, canopies, and grasslands. These animals began to burrow, climb, fly and take advantage of new food sources.
Our research shows that tetrapods (amphibians, reptiles, mammals and birds) have explored only one third of habitable ecological space and that without human influence, biodiversity would continue to increase exponentially.
Examining the biodiversity of tetrapods, we realized that their taxonomic diversity (the number families) closely matched their ecological diversity (the number of niches they occupied) through their 400 million years of evolution, and that there appears to be little evidence for competition as the driving factor for their great diversity.
Diversity was driven by the dominant animals at the time, which expanded into empty niches. Competition did not play a big role in the overall pattern of evolution. For example, even though mammals lived beside dinosaurs for 60 million years, they were not able to out compete the dominant reptiles. But when the dinosaurs went extinct, mammals quickly filled the empty niches they left and today mammals dominate the land.
Growing and shrinking biodiversity is closely tied to the niches animals occupy, so habitat destruction is a key aspect of extinction. In Earth’s past there have been incentives for animals to move into new modes of life, where initially resources may seem unlimited, there are few competitors and possible refuge from danger.
However, if niches are destroyed more often than created because of man’s influence on the environment, animals won’t have the opportunity to adapt and biodiversity won’t continue to grow.
Most people are familiar with the extinction that killed the dinosaurs but another series of extinctions, at the end of the Permian, about 250 million years ago, were far worse, killing off over 90% of life on earth, including insects, plants, marine animals, amphibians and reptiles. A new study, published by myself and Michael Benton in the Proceedings of the Royal Society B, indicates that it took ecosystems 30 million years to recovery from this devastating event.
The Permian extinctions occurred in three waves, the largest being at the boundary between the Permian and Triassic periods, 252 million years ago; an event that was exacerbated by two earlier extinctions. This was the most devastating ecological event of all time, thought to be caused by large scale volcanism in Russia which produced the ‘Siberian Traps’, covering over 200,000 square kilometers (77,000 square miles) in lava. Ecosystems were destroyed worldwide, communities were restructured and organisms were left struggling to recover. Disaster taxa, which are opportunistic organisms filling in the empty ecospace left behind by the extinction, insinuated themselves into almost every corner of the sparsely populated landscape.
Previous work indicates that life on Earth bounced back quickly after the Permian extinctions, but this was mostly in the form of disaster taxa, such as the hardy Lystrosaurus, a barrel-chested herbivorous animal, about the size of a pig. However, this new research indicates that specialized animals forming complex ecosystems, with high biodiversity, complex food webs and a variety of niches took much longer to recover. It is thought that this long recovery was due to the successive waves of extinction, which never gave life a chance to recover as well as prolonged environmental stress which continued into the Early Triassic.
It would not be until the great diversity of the Late Triassic, which included dinosaurs, pterosaurs, crocodiles, archosaurs, amphibians and mammals, some 30 million years after the big event, that diversity in terrestrial communities was restored.
I have enjoyed writing Fish Feet but unfortunately have not been able to keep up with being a new parent and writing up my thesis. While I won't be writing regular posts please feel free to visit for occasional updates to my research and some shameless self promotion:)
For those of you that are still around, Thanks for reading! Sarda
...and quite frankly I am pretty pissed off that his lectures have been cancelled. James Watson, Nobel Prize winner and cofounder of the structure of DNA told the Times of London that "there is no firm reason to anticipate that the intellectual capacities of peoples geographically separated in their evolution should prove to have evolved identically." So guess what? Most venues hosting Watson have decided to cancel his forthcoming public engagement talks.
Unfortunately such comments have often been made by Watson and while I don’t agree with him, I certainly defend his freedom of expression. I also don’t think he has a special ‘responsibility’ being a Nobel Prize scientists to censor himself. It is unfortunate that a man with so much knowledge and experience is drawing such conclusions but sweeping his remarks under the rug doesn’t help people. The organizers of events across the country are sticking their heads in the sand. By canceling these talks and making the decision that we shouldn’t be subject to his perspectives, they have denied us the opportunity to see a great scientist and to question him on his views.
Do we discard the great contributions of scientists, politicians, artists, because of their views? Clearly we haven’t. Personally I admire the work of Marie Stopes, known for her contributions to palaeobotany and advancement of women’s issues, but often not remembered for her views on race and eugenics. Another big contributor to my field of work was Swiss-American zoologist and geologist, Louis Agassiz who is known in other circles for his perspectives on racism and eugenics. Sir Winston Churchill, a man who was once chancellor of my own university and also who lent his name to my secondary school, was very vocal about his views on sex, race and the mentally disabled.
Unfortunately, an easy scapegoat has been made of Watson. The man’s contributions to science are a different matter than his personal views. If you’re on facebook and feel strongly about this issue, The Ministry of Love (a reference to Orwell’s 1984), is a group formed in protest of canceling Watson’s lectures.
• Visit The Other 95%, where Kevin and Christopher have composed a beautiful melody about Receptaculites, a problematic Palaeozoic fossil.
• Chris at the Catalogue of Organisms, debates the true nature of the same organism, the enigmatic Receptaculites. Is it a plant or an animal?.
Vertebrate Palaeontology
• Julia at the Ethical Palaeontologist describes an amazing find: a Psittacosaurus Dinosaur Nursery from the Cretaceous Yixian Formation in NE China.
• GrrlScientist at Living the Scientific Life takes a look at features on a Mongolian Velociraptor fossil which reveal that this dinosaur was indeed, feathered.
• Brian Switek of Laelaps celebrates the Golden Age of Paleontology with a comprehensive posting on feathers, nests and dinosaurs.
• Eric at The Primate Diaries has identifies an original cast member of Survivor, Homo floresiensis, a 3-foot tall hominin cousin that lived on the Indonesian island of Flores 18,000 years ago.
• Kambiz of Anthropology.net discusses Early Homo Postcranial Fossils from Dmanisi, specifically, the cranial remains.A little controversy has been started up this week about The Scientist's vote for favorite life science blogs. The Scientist asked some of the most popular bloggers to give their opinion on the best science blogs and as many people have pointed out, including Chris at Highly Allochthonous, Julia at The Ethical Palaeontologist, and Brian at Laelaps, there are no women on this list.
Well I am sure I would get shot down by many of my female colleagues for saying this but let’s be honest, there just aren’t as many female scientists as male scientists, especially as you climb the ‘academic ladder’. Why not? As an undergraduate I noticed that the ratio of women to men is actually greater in biology and geology was reasonable even. A quick survey of my graduate colleagues shows a ratio of 12 men to 7 women over the last four years. And as you continue, the proportion of women gets smaller, we have 10 men listed in our department as staff and postdoctoral researchers and only 4 women. And check out how many members of the Royal Society are female (5%). So where do all the women go to?
Is it true that many women still give up their careers for a life at home? Is academia still heavily weighted against them and women leave the field because they don’t feel their career advance as fast as those of their male colleagues? I don’t know to be honest. But there is no doubt there are fewer female role models in academia especially in the fields of physics, math, computing and engineering where their ratio often dwindles to less than 10%.
So anyway, back to The Scientist, I am sure they didn’t deliberately mean to exclude female science bloggers. Looking at my own blogroll I realize most of the science blogs I read are written by men, I think it is representative of the ratio of the sexes in academia, something to think about.
