Evolution

Recoding Genes: How Post-Transcriptional Editing is Giving Squid the Upper Hand

24 April, 2015 by

Natural selection is incredibly good at adapting organisms to their environment, even those environments that are harsh and difficult to live in. But the changes currently happening to the World’s climate, hydrology and land-use may be too rapid for natural selection to act, in most cases. For some species, natural selection has provided the tools to adapt more rapidly, through behavioural or physiological changes. A few species have gone further still, evolving the ability to edit their own genes as they are expressed. Recent research shows this ability is used rampantly by certain species of squid, which may explain why they have responded relatively well to human impacts on the environment so far.
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Evolving the Modern Dinosaur

4 April, 2015 by

There are more than 10,000 species of living, breathing dinosaurs on Earth today. It’s just that we call them birds. And while a chicken might seem like a measly ancestor for the enormous T-rex, modern birds can teach us a lot about dinosaur evolution. A huge genome sequencing project, which recently culminated in the publication of nearly 50 genome sequences and the most accurate tree of bird evolution to date, has further blurred the line between bird and dinosaur. Spurring a plethora of studies into the origins of our modern feathered, singing friends, the December 2014 edition of Science taught us that the transition from dinosaurs to birds was gradual and began long before the Dinosaurs were gone. It taught us that it involved multiple independent origins of bird song, a characteristic that now dominates around 10% of the genome. And it taught us that the evolution of flight was facilitated by new genes and new gene regulation, but also by the loss of genes.

Making a Chicken from a T-Rex

Last October, the Therapod Working Group constructed a new phylogeny (family tree) for Dinosaurs, based on morphological characteristics measured in fossil remains of over 150 different species. The new tree revealed fascinating insights into the nature and pace of avian evolution.

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Sloths Move Slow, Evolve Fast

11 March, 2015 by

Sloths might be notorious for their leisurely pace of life, but research published last year shows they are no slow coaches when it comes to evolution.

Sloths, as we know and love them, are small, slow-moving creatures found in the trees of tropical rainforests. But modern sloths are pretty odd compared to their extinct relatives. Sloths (Folivora) are represented today by just six species in two families; the Megalonychidae (two-toed sloths) and the Bradypodidae (three-toed sloths). But 20,000 years ago there were perhaps as many as 50 species of sloth spread across the globe, and most were relatively large, ground-dwelling animals quite unlike modern sloths. While most modern sloths weigh in at a modest 6kg, extinct species such as Megatherium americanum and Eremotherium eomigrans could weigh up to 5 tonnes!

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The Cuckoo Underworld

14 January, 2015 by

Most birds make nests, and spend their time foraging to feed and care for their chicks. Cuckoos, on the other hand, don’t waste their time with any of that, they simply lay their eggs in another bird’s nest and let them do all the heavy lifting. This might sound like the easy option, but in fact cuckoos have made a whole lot more work for themselves trying to evade and deceive their neighbours. When cuckoos succeed in their trickery, their unsuspecting host suffers, producing fewer young that year and wasting time and energy. So, evolution has pitted host birds against cuckoos, with each side developing increasingly sophisticated techniques to try and get their own way. Host birds mob potential attackers, while cuckoos use mimicry to avoid detection, and threaten defectors with serious consequences.

Cuckoos are famous for taking advantage of their unsuspecting neighbours; laying eggs in their nest and leaving their unwitting host to raise the chicks. The world cuckold, used to refer to the husband of an adulterous wife, originates from the cuckoo bird. There are over 50 species of parasitic cuckoo in the family Cuculidae; some are generalists who will lay their eggs in any available nest, others specialise in one or a few ‘host’ species, but all are engaged in an evolutionary battle with the species they parasitise – an arms race, if you will. Species parasitised by cuckoos are at a disadvantage – in the best case they are merely wasting resources raising an unrelated chick, in the worst case the chick will hatch early and push out the other eggs in the nest, meaning that the unlucky bird in question loses an entire clutch. In each generation, therefore, natural selection will favour host birds that are able to avoid parasitism. The birds might evolve to be more discerning, for example, identifying the appearance of cuckoo eggs and removing them, or selecting nest sites that are more difficult for the cuckoos to access. Equally, in each generation the cuckoos that are most successful in deceiving and parasitising their neighbours will produce more offspring and their traits will be favoured by natural selection. Cuckoos might evolve eggs that more closely resemble those of their host, or very rapid egg incubation to ensure their chick hatches first. Ultimately, neither species wins, with evolution demanding increasingly sophisticated tactics for successful parasitism in cuckoos, and traits to thwart parasitism in the host species.

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Genomic Evolution of Our Feline Friends

31 December, 2014 by

Cats are one of the most common domesticated animal on Earth, with an estimated 400 million worldwide. And yet they lack many characteristics that tended to make animals good for domestication. They are solitary hunters, making them relatively poor at responding to and valuing social hierarchies. So how exactly did early humans domesticate our feline friends? Recent research suggests stroking and treats may have been key to winning them over.

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What’s So Sexy About a Beard?

27 November, 2014 by

Beards. You either love ’em or you hate ’em. Science tells us that beards make a man look more masculine, older and more powerful. Apparently women think they’ll make better fathers. But new research published earlier this year suggests that the attractiveness of beards might merely come down to their novelty – beards are under negative frequency-dependent sexual selection, and we may soon pass peak beard.

As movember draws to a close, I for one shall breath a sigh of relief – don’t get me wrong, I’m all for it as a charitable campaign and I’m sure it does a great deal of good, but as one of many single women who doesn’t appreciate facial hair, November has recently become the most dangerous month for dating. You can argue about it until you’re blue in the face (and I have done – well, almost!) but ultimately the facial hair debate is a matter of opinion.

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Bacterial Threesome Throws up Evolutionary Surprise

19 November, 2014 by

Symbiotic relationships, where two organisms ‘live together’ and rely upon each other to survive, are surprisingly common in the animal kingdom. The more we look, the more we find. What is less common, or at least less well documented, is the occurrence of speciation events within these partnerships. A recent study has revealed the first documented case of the speciation of a bacterial symbiont, inside the cells of a cicada. Even more interestingly, scientists believe it may have been little more than an evolutionary screw-up!

Symbiotic relationships can be quite casual, or extremely intimate, and are literally all around you. And inside you. The mitochondria inside your cells are symbiotic bacteria that joined our cells billions of years ago. Mitochondria show a pattern that is common in such intimate symbiotic relationships – over millions of years, partners in the relationship each have a reduced genome, with a complementary set of genes. This in turn makes them even more dependent upon each other. Mitochondria have only about 37 genes, compared to 1000 in a free-living bacteria. They simply don’t need many of their genes anymore because their host cells carry them. This is known as relaxed selection – because both members of the partnership carry the genes, a mutation in a gene in one partner will probably have no effect. The other member still has a functioning version of that gene, so the organism as a whole shows no negative symptoms, and natural selection is blind to the mutation. Only when both copies of a particular gene are degraded will natural selection step in, meaning that over time random chance will degrade complementary sections of each genome.

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Parasitic Fish Reveal Insights into Brain Evolution

23 October, 2014 by

What can this squiggling, toothed eel-like creature possible tell us about our own brains? Well, the lamprey, although ugly, occupies a pivotal place in the evolutionary tree. Research on captive lampreys can tell us about the earliest evolution of the vertebrate brain and yield insights that may help to cure and treat neurological disease. A new study published in Nature last month suggests that the human pattern of development in an important region of our brains may have evolved much earlier than we thought, in a creature that looks much like a modern-day lamprey. So perhaps lampreys can tell us more about our brains than you might have thought!

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Mega Penguin

2 October, 2014 by

Penguins are certainly one of the more cute and charismatic of the Antarctic fauna, but would people be so fond of penguins if they were over 2 metres tall? Fossils recently unearthed in Antarctica have revealed that giant penguins used to roam this icy continent.

Palaeeudyptes klekowskii, discovered on Seymour island off the Antarctic peninsula, was a penguin weighing 115 kilograms and towering above most people at 2m (6ft7). That’s two and a half times heavier, and nearly twice the height of an Emperor penguin (Aptenodytes forsteri)!

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