Lizards
edyong | March 9, 2010Not Exactly Pocket Science is a set of shorter write-ups on new stories with links to more detailed takes by the world's best journalists and bloggers. It is meant to complement the usual fare of detailed pieces that are typical for this blog.
Cold-proof tongue allows early chameleon to catch early insect
Chameleons are some of the most versatile of lizards. They live in baking deserts and freezing mountaintops and part of their success hinges on a weapon that works just as well in the warmth as in the cold - its tongue. Relying on stored elastic power for its ballistic strike, the…
edyong | February 21, 2010Whiptail lizards are a fairly ordinary-looking bunch, but some species are among the strangest animals around. You might not be able to work out why at first glance, but looking at their genes soon reveals their secret - they're all female, every single one. A third of whiptails have done away with males completely, a trick that only a small minority of animals have accomplished without going extinct.
Some readers might rejoice at the prospect of a world without males but in general, this isn't good news for a species. Sex has tremendous benefits. Every fling shuffles the genes of the two…
edyong | December 28, 2009
In the White Sands National Park of New Mexico, there are three species of small lizard that all share white complexions. In the dark soil of the surrounding landscapes, all three lizards wear coloured coats with an array of hues, stripes and spots. Colours would make them stand out like a beacon among the white sands so natural selection has bleached their skins. Within the last few thousand years, the lesser earless lizard, the eastern fence lizard and the little striped whiptail have all evolved white forms that camouflage beautifully among the white dunes.
Erica Bree Rosenblum from…
edyong | October 29, 2009The Northern short-tailed shrew is a small, energetic mammal that lives in central and eastern North America. The Mexican beaded lizard is a much larger reptile found in Mexico and Guatemala. These species are separated by a lot of a land and several million years of evolution, yet they share astonishing similarities. Not only are they both venomous, but the toxic proteins in their saliva have evolved in very similar ways from a common ancestor, converging on parallel lethal structures independently of one other.
This discovery, from Yael Aminetzach at Harvard University, shows that…
edyong | September 8, 2009When danger threatens many lizards can detach their tails, leaving them behind as decoys in the hope that the predator will attack it rather than the lizard itself. But the tail doesn't just lie there as bait. For half an hour after they've been severed, the disembodied tails perform a complex dance, flipping, lunging and jumping up to an inch in the air. These acrobatics serve to distract the predator even further.
For the first time, Timothy Higham and Anthony Russell have studied the movements of severed gecko tails to understand how they can move in such complex ways without any input…
edyong | July 18, 2009We think of spiders as fearsome hunters, spinners of webs and treacherous mates, but construction workers? Yes, that too. Some groups of spiders - trapdoor and wolf spiders - dig tunnels that they use to ambush passing insects. But these tunnels can also provide shelter and accommodation for other animals, including one of the rarest of Australia's lizards - the pygmy blue-tongue lizard. It seems that the lizard's survival depends entirely on the spiders.
The pygmy blue-tongue is a native of South Australia. It's so rare that zoologists thought it extinct for over 30 years and it re-emerged…
edyong | June 5, 2009For humans, sex is a simple matter of chromosomes: two Xs and we become female; one X and a Y and we develop into males. But things aren't so straightforward for many lizards - many studies have found that the temperature of the nest also has a say, even overriding the influence of the chromosomes. But the full story of how the lizard got its sex is even more complicated. For at least one species, the size of its egg also plays a role, with larger eggs producing females, and smaller ones yielding males.
The discovery comes from Richard Shine's group at the University of Sydney. In earlier…
edyong | May 18, 2009For the longest time, people believed that the world's largest lizard, the Komodo dragon, killed its prey with a dirty mouth. Strands of rotting flesh trapped in its teeth harbour thriving colonies of bacteria and when the dragon bites an animal, these microbes flood into the wound and eventually cause blood poisoning.
But that theory was contested in 2005 when Bryan Fry from the University of Melbourne discovered that a close relative, the lace monitor, has venom glands in its mouth. The discovery made Fry suspect that Komodo dragons also poison their prey and he has just confirmed that in…
edyong | January 7, 2009
For humans and other mammals, sex is neatly determined by the X and Y chromosomes. If you have a Y you are male, and without it you are female. Reptiles however, use a variety of strategies, and the mammalian X/Y system is just one of them.
In some species, the female is the one with different chromosomes, in this case Z and W, and the male has two Zs. And some reptiles ignore sex chromosomes altogether. For them, an individual's sex is determined by the temperature that their eggs were incubated at.
Scientists had long believed that these strategies were mutually exclusive with each…
edyong | January 5, 2009
One hundred and seventy-four years ago, Charles Darwin first set foot on the Galapagos Islands aboard the Beagle. Since then, the islands and the unique species they house have been a source of inspiration for many an evolutionary biologist. Even so, it is gratifying to see that even now, on the bicentennial of Darwin's birth, the Galapagos have not yet finished yielding their secrets.
During Darwin's five-week stint on the Galapagos, he observed two types of iguana. One was a marine version that, uniquely for lizards, swam and fed in the ocean, and the other was a cactus-eating landlubber…
edyong | November 12, 2008
Hair, or fur, is one of the hallmarks of mammals, the group of animals to which we belong. It is an evolutionary innovation that provides us with protection and helps us to maintain our constant body temperature And while hair is a uniquely mammalian feature, its genetic building blocks are anything but. A new study has found that genes responsible for building the locks on your head have counterparts that construct the claws of lizards.
Hair is made of proteins called keratins, which interact with each other to form long, hard filaments. Keratins are widespread in the animal world but…
edyong | October 3, 2008
According to Christian lore, Mary gave birth to baby Jesus without ever having had sex with Joseph. A biologist might describe this as 'parthenogenesis', the Greek version of the more familiar phrase 'virgin birth'('parthenos' means virgin, and 'genesis' means birth). The New Testament aside, shunning fertilisation and giving birth to young through parthenogenesis is rare among higher animals, occurring in only one in every thousand species. Nonetheless, two Christmases ago, eight virgin births took place in the English town of Chester. The mother's name was Flora and she was a komodo…
edyong | September 20, 2008
The decades that make up a typical human lifespan can seem like vast stretches of time to us. But to the forces of evolution, they are mere temporary blips. Common wisdom has it that evolution occurs over geological timescales - thousands and millions of years. As such, evolutionary biology takes a lot of criticism for being a 'descriptive science', being less open than other fields to that fundamental aspect of science - experimentation. Though there are exceptions, those who study evolution must mostly be content to observe snapshots of life, either present or entombed in rock, and…
edyong | July 1, 2008The mayfly is known for its incredibly short adult life. After spending months as larvae, the adults finally hatches only to fly, mate and die within the space of a day. Now, in the dry south-west corner of Madagascar, scientists have discovered the lizard equivalent of the mayfly - Labord's chameleon (Furcifer Labordi).
The lifespan of Labord's chameleon is hardly as compressed as that of a mayfly, but it is extraordinarily short for a tetrapod (an animal with four legs and a backbone). From laying of egg to kicking of bucket, the lizard's entire life is played out in a year and 7 months…
edyong | June 13, 2008Many groups of animals, from humans to dinosaurs to kangaroos, have evolved the ability to stand and walk on two legs. In all of these cases, the move from four legs to two has provided clear advantages. Kangaroos save energy because their hopping is so efficient, birds have freed their front pair of limbs for use as wings, and humans use ours for manipulating tools and objects.
But some species of lizards also rear up on their hind legs from time to time, particularly when running. The Australian frilled lizard does it so readily that it has earned the nickname of 'bicycle lizard'. And the…
grrlscientist | April 23, 2008tags: researchblogging.org, evolution, speciation, Pod Mrcaru lizard, Podarcis sicula, reptiles
Pod Mrcaru lizard, Podarcis sicula.
Image: Anthony Herrel (University of Antwerp) [larger view]
Evolution has long been thought to occur slowly, due to small and gradual genetic changes that accumulate over millions of years until eventually, a new species arises. However, recent research has been calling this assumption into question. According to a study that was just published by an international team of scientists, dramatic physical changes can occur very rapidly -- on the order of just 30…
edyong | March 17, 2008
Geckos are nature's champion climbers. With remarkable ease, they can scamper across ceilings and up smooth vertical surfaces, and they do so at speed. A vertically running gecko can cover 15 times the length of its body in a single second. So far, scientists have focused their attention on the gecko's amazingly adhesive feet but a new study demonstrates the importance of a neglected piece of their climbing gear - their tails. Geckos use their tails to stop themselves from falling, and to land safely if they do.
A gecko's foot is a marvel of biological engineering. Rather than relying on…