This week...

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:

• Vancouver Sun (Newspaper)
• As It Happens, CBC (Radio)
• Pharyngula (Blog)

By the way, if you are interested in reading the paper for yourself it is available to download at my academia.edu page.

Thank you to everyone who has provided feedback and some critical thinking towards the research.

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.
Download PDF

Earth’s biodiversity is driven by more than just Survival of the Fittest

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.
Download PDF


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.

Ecosystems took 30 million years to recovery from the Permo-Triassic Mass Extinction

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.

So long and thanks for the fish!

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

Boneyard #6

Welcome to Fish Feet, host of the 6^th Boneyard blog carnival!

Mysterious Fossils
• 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
• Neil at Microecos examines the challenges that faced the first vertebrates which crawled onto land, specifically in regards to developing auditory capabilities.

• 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.


Human Evolution
• 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.


I’m glad to have hosted the carnival and have enjoyed reading all of the great submissions! Visit the Boneyard again in two weeks.

Where did all of the chicks go?

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.

If you like this blog...

If you like this blog please leave a comment about it at The Scientist's vote for favorite life science blogs.

Thanks!!

Polar Bears Hunt Belugas

Feeling a little uninspired today, I hope you don't mind a repost from March on an amazing topic that few people believe until they see the footage (the most popular source is David Attenborough's Planet Earth).

Polar bears live a feast and famine lifestyle. They are large animals (an adult males weighs 300-600kg) that live in the freezing tundra so they have huge metabolic needs. They normally prey on ringed seals but will eat almost anything they can catch, including walruses, birds, eggs and occasionally they supplement their diet with a big, juicy, beluga whale!

Beluga whales are distinctive for their pale skin and large melon shaped head. These animals can grow up to 5m (16ft) in length and live in large pods, mainly in the Arctic and Canadian Subarctic. Belugas live close to coastlines and in winter they occasionally become trapped in savsatts, small openings in ice packs. Belugas can find themselves the victims of shrinking savsatts, which they use to breath. Each animal will take a turn coming up for air and in the worst of winter, their movement is all that keeps the savsatt open.

Hence an opportunity that a wandering polar bear may chance by and certainly one he can’t resist. The bear will jump in the water, clubbing the trapped whale with his paw and gorging it with his claws. It may take several attempts but the bear usually succeeds in his catch and drags the whale’s carcass on to the ice for a feast. Other polar bears will share in the prize and any leftover kill will be happily devoured by scavenging arctic foxes and gulls.

If you find this post interesting I encourage you to also check out Darren Naish’s very cool post on Wolf-Hunting Eagles

More information can be found at Polar Bears International.

Blogroll Additions

Thanks for your enthusiastic response and all of your links. Sorry if your blog had fallen off the roll; I may have lost a few when I upgraded to Goggle’s new blogger. The blogroll is still open so if you would like to be added, leave a comment. Enjoy the new additions…

Jon Swift is a reasonable conservative who likes to write about politics and culture. This week he asks "Are We Tasering People Enough?"

Check out Andrew's new blog, The Naked Galaxy, about everything and anything science.

Zach Miller writes When Pigs Fly Returns!, a blog from Anchorage, Alaska on all things palaeo related.

And finally, Jacob Haqq-Misra muses on spirituality and science in Reflections, Ideas, and Dreams.

Announcement: Blogroll Enrollment

Well I haven't been very diligent in keeping up my blogroll. If you would like a link to your site from Fish Feet, please leave a comment on this post with your blog’s name and URL and I will add your link to my blogroll (probably – no spam please). I appreciate links back also.

Oekologie #9

Welcome to Fish Feet, host of 9th Oekologie blog carnival!

Population & Extinction
• GrrlScientist of Living the Scientific Life talks about Bluefin Tuna, will they soon be the Dodos of the sea?

• Jeremy at The Voltage Gate writes about the decline of antelopes in African national parks.

• John at A DC Birding Blog reviews the IUCN Red List 2007 and its implications.

• James at Direction not Destination researches ‘The Tyranny of Power’ phenomenon in white-tailed deer distributions.

Species Interaction
• Corey at 10,000 Birds explains why a blight on conifers can be a boon for certain birds.

• Jenn at Invasive Species Weblog describes the impact of invasive plants in Massachusetts.

• Kevin at The Other 95% explores the fascinating world of jumping spiders and wolf spiders.

• Madhusudan at Reconciliation Ecology contributes a riveting article on the annual commute of the Bar Tailed Godwit, 11,570 km from Alaska to New Zealand.

Microbial Ecology
• Tara at Aetiology imagines the possibility of using E. coli as a cavity fighter.

• Christina at Deep Sea News considers the importance of studying deep-sea coral microbial ecology.

Disease & Disaster
• Christian of Med Journal Watch shares new research on malaria pest control 45 years after Silent Spring.

• Greg at Evolution ... not "just a theory" anymore examines different cultural perspectives on building homes in disaster prone areas.

Humans & Environment
• Eric at the The Primate Diaries investigates the downstream effects of biopiracy.

• Devon at Ask the CareerCounselor gives readers invaluable advice on switching to a career in environmentalism.

• Shaheen at GNIF Brain Blogger relates the biochemistry of genetics and stress.

I’m glad to have hosted the carnival and have enjoyed reading all of the great submissions! Next month visit Oekologie at Laelaps.

Twins: Identical, Mirror Images, Fraternal and Chimeras

Cloning is not a human invention; nature has been creating clones for millions of years, among all organisms including humans. Nature’s clones, identical twins, are born in approximately 1 / 1000 births. Identical twins come in two varieties: identical and mirror images. Both share 100% of their DNA and but in mirror image twins, small differences are ‘reflected’. Examples include skin variations such moles, dental patterns, hairlines and handedness.

The development of a truly identical twins versus mirror image twins comes down to timing. A single sperm will fertilize a single egg and begins development by splitting into more cells. If this group of cells, now called blastocyst splits into two separate parts in the first 9-12 days, identical twins will be born. But if the split occurs after that, they will be mirror-images of each other.

Fraternal twins are an entirely different matter. Fraternal twins are no more identical than any other sibling pair and are the result of two separate sperm fertilizing two separate eggs. This is can occur naturally, the result of the mother releasing more than one egg at ovulation. It may also be the result of medical intervention as many women take fertility drugs to improve their chances of conception. There is also a hereditary link as the incidence of fraternal twins do occur more often within a family.

Many people have seen the popular American television show CSI (Crime Scene Investigators) and may recall the episode with the Chimera, a man who had two sets of DNA. This phenomenon occurs when the blastocysts of developing fraternal twins fuse, resulting in a single individual with two sets of DNA. This condition usually results in a fully functional individual and is not detected unless a clear abnormality prompts testing. Though it has been considered a rare condition, it is found to be more common than originally thought in a variety of animals, including humans. And the condition is more common among children conceived through in vitro fertilization than naturally.

By the way, you can read about the amazing birth of identical quadruplets from my hometown, Calgary, Canada here.

A spin around the blogosphere this week…

You may remember Darren Naish’s post on wolf-hunting eagles. Well Darren has recently posted a video on his blog in which an unfortunate young deer gets killed by big bad eagle.

Also, Carl Zimmer has created a photo album of geeky scientific tattoos and you can even explore even more at Street Anatomy.

And don't forget that Fish Feet will be hosting the Oekologie blog carnival in September.

Why does my baby have a tail?

As I’m having a baby my mind has recently been turned to thoughts of the very weird and wonderful world of developmental biology. As a new parents tracks the progress of their child, you can’t help wonder about some of the really bizarre stages it goes through.

Some of the odd developments (gill slits and tails as examples) can be explained by the research of a 19/20th century German researcher, Ernst Haeckel. This eminent man was more than a scientist, he was a, physician, philosopher, artist and teacher. Haeckel’s contribution to biology was immense, in addition to naming and identifying thousands of new species (one his beautiful colour plates is displayed on the right), he contributed many large-scale concepts to the fields of ecology and biology. His most controversial theory is often referred to as Recapitulation Theory.

This theory is often stated as "Ontogeny recapitulates phylogeny", simply meaning that as an organism develops, it replays its evolutionary history. His theory is closely tied to the figure below (redrawn by Romanes in 1892), which shows striking similarities in the various stages of development of some vertebrates. We now know that Haeckel, perhaps in an attempt to bolster his theory or perhaps because his specimens were incomplete, embellished the drawings to some degree; so these examples must be taken with a grain of salt but hey are correct in a generalized sense. Haeckel, a great believer in the works of Charles Darwin, used this illustration and many of his other drawings to support the theory of evolution and argued that as an individual develops, it repeats the full evolutionary development of its species.
Now strictly speaking, Haeckel wasn’t exactly right, and a developmental biologist would set you straight about exactly how wrong Haeckel was, but I’m not going to be debating this point because no modern biologist would taken his theory to be literally true. What I would like to focus on is the broader picture that Haeckel’s observations support. We are all fundamentally related and simply, those of us that share a closer common ancestor will look more alike. So it is not a surprise that we resemble other mammals more closely than we resemble a fish, frog or reptile. Also, evolutionary steps are often like ‘additions’, adding new features to the developing form, so again it is not a surprise that our own human embryos go through stages resembling that of other animals.

If Haeckel were to be taken literally, at some point a growing human embryo would be a viable fish, amphibian, reptile, or early primate. But in fact a human embryo can only ever be a human. The commonalities we share with other animals that Haeckel discovered are indicative of our common ancestry and his theory helps us understand that stages in our embryonic development reflect these connections. Some of the weird things human embryos go through include:

• Early on the embryo develops gill slits (more correctly called pharyngeal arches) in its neck. In a human, the first gill bar (which supports the pharyngeal arch) develops into the lower jaw as well as the ear bones (malleus and the stapes). The gill slits will then close, leaving just one open for the development of the ear opening

• By the fourth week a clear tail is seen in the human embryo. It recedes after a few weeks and these tissues form what is commonly known as the tailbone (coccyx).

• Around the fifth month of gestation the embryo develops lanugo, a fine, downy hair, which covers its entire body. It provides some insulation, as the child has little in the way of fat reserves. This hair is usually lost by birth, though is often seen on premature infants.

Tangled Bank #86

Welcome to Fish Feet, host of the 86th Tangled Bank blog carnival!

The Scientific Process
• Kevin of The Other 95% discusses metrics of scientific advancement and their impact on progress.

• Sunil at Balancing Life gives readers invaluable advice on writing grant proposals.

• Christian of Med Journal Watch writes about the artificial settings of diet trials and the value of their findings.

Evolution
• Shalini at Scientia Natura debates the impact of a recent palaeoanthropological discovery on the theory of evolution?

• CAD of VWXYNot? describes how the progression of tumorigenesis mirrors the process of evolution by natural selection.

• Eric of The Primate Diaries discusses offspring abandonment in the ancient and natural world.

Ecology
• Jeremy at The Voltage Gate contributes a riveting article on the ecology of fear in Yellowstone National Park.

• Scott of Dammit Jim! I’m a biologist not a… posts a cool youtube video and explores the curious mating rituals of jumping spiders.

• Mike at 10,000 Birds explores the diversity of Waxwings.

Agriculture and Environment
• Matthew of Behavioral Ecology muses about how even parasite-resistant sheep avoid eating shit!

• Jeremy of Agricultural Biodiversity Weblog discusses variation in the glycaemic index of various crops.

• Emmett from The Natural Patriot shares his perspective on the writing and philosophy of author and environmentalist, Richard Louv.

• Martin of Aardvarchaeology reviews Alan Weisman’s book, the The World Without Us

Human Biology, Diet and Medicine
• Paddy of Swedish Extravaganza writes a balanced discussion on the ethical aspects of vegetarianism.

• Cathy of Lab Cat talks about pre and probiotics.

• GrrlScientist of Living the Scientific Life talks about a bone hormone, which is linked to obesity and Type 2 Diabetes.

• Alvaro of Sharp Brains has submitted a podcast interview with neuropsychologist Dr. Elkhonon Goldberg who talks about brain improvement research.

• FitBuff of Total Mind and Body Fitness reports on a recent study which examines the unconscious signals we use to find Mr. or Mrs. Right!

Genetics
• Hsien of Eye on DNA imagines the possibility of genome sequencing being available to the public.

• Lev at Ouroboros writes an article about protein abundance in long-lived worm mutants.

• Jeremy at Another Blasted Weblog discusses restriction endonucleases, the molecular scissors that allow biologists to cut DNA.

I’m glad to have hosted the carnival and have enjoyed reading all of the great submissions! Two weeks from now on August 29, visit Tangled Bank again at Balancing Life.

Long Absence

Sorry I have been absent for so long. Life has been getting pretty busy, with grad school and a new baby on the way. But I hope to be back to blogging (at least once a week, if not more often) and Tangled Bank has given me the kick in the pants I need to get back to it! Visit us on August 15 to check Tangled Bank #86!

Monster Pig Debuked!

Apparently this 'Monster Pig' shot by an 11-year old boy in rural Alabama is a fake (big surprise) Check out the full story of photo manipulation here.

The cat with 26 toes

Thanks to Janine for sending in this story about a VERY polydactyl cat. Last month I wrote about the evolution of five fingers and toes and the constraints on this arrangement. Though loss of digits is not an uncommon evolutionary change, gaining digits is very rare. It is a phenomenon seen in polydacyl cats; however, I don't think anyone understands why cats are able to increase the number of their digits without 'repercussions' to the rest of their patterning. Anyway, click here to read about the polydactyl cat who has 26 fingers and toes!

Cretaion Museum reveals Adam's sordid past

I took a long weekend so I guess this story is a few days old but I had to rely it because it is so funny! Thanks to Hank Campbell who organizes Scientific Blogging for sending it along.

The Creation Museum of Petersburg, Kansas has been wrought with criticism since before it even opened, but most recently, they have been embroiled in a ‘moral scandal’ by an employ hired to tell the story of the fall of man.

A variety of actors were hired to play out scenes from the bible and the man chosen to play God’s golden boy, Adam, has now been revealed to have a ‘sordid’ history. Eric Linden, owns a website called Bedroom Acrobat, on which he is (allegedly -I cannot say this myself as the site has apparently crashed due to traffic overload) pictured. Linden, a graphic designer, model and actor purchased the domain name for this site which mostly sells clothing.

Museum administrators were swift in removing the 40-second video in which he appeared from the display. “We are currently investigating the veracity of these serious claims of his participation in projects that don’t align with the biblical standards and moral code upon which the ministry was founded,” Answers for Genesis spokesman Mark Looy said in an electronic statement.

T. rex didn't turn on a dime

Scientists now say that the "Terror of the Cretaceous" may not have been that bad after all. A new study indicates that T. rex had a hard time getting its jaws into fast, agile prey.

An American team of palaeontologists have used detailed computer models to work out the weight of a typical Tyrannosaurus and determine how it ran and turned. The results indicate a 6 to 8-tonne T. rex was unlikely to have topped 40km/h (25mph) and would have taken a few seconds to swivel 45 degrees.

The computer model estimated that a high center of mass and large inertia would have had been responsible for the slow movement and that T. rex could have been out-maneuvered by agile prey.

Dr Paul Barrett, of London's Natural History Museum, commented, "This is another finding that undermines the kind of idea of T. rex as a super-predator. But it has this huge mouth filled with 60-odd, 30cm-long teeth, so it was still a formidable animal."

The research was published in the Journal of Theoretical Biology.