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Boa Constrictor Gives Birth to Clones

Posted on November 3, 2010  Comments (0)

Snake gives ‘virgin birth’ to extraordinary babies

A female boa constrictor snake has given birth to two litters of extraordinary offspring. Evidence suggests the mother snake has had multiple virgin births, producing 22 baby snakes that have no father. More than that, the genetic make-up of the baby snakes is unlike any previously recorded among vertebrates, the group which includes almost all animals with a backbone.
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“All offspring are female. The offspring share only half the mother’s genetic make-up,” he told the BBC.
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Humans for example have X or Y sex chromosomes; females have two X chromosomes and males have a combination of an X and a Y chromosome. In place of X and Y, snakes and many other reptiles have Z and W chromosomes.

In all snakes, ZZ produces males and ZW produces females. Bizarrely, all the snakes in these litters were WW. This was further proof that the snakes inherited all their genetic material from their mother, as only females carry the W chromosome.

“Essentially they are half clones of their mother,” says Dr Booth. That is because the baby snakes have inherited two copies of one half of their mother’s chromosomes, including one W chromosome.
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More astonishing though, is that no vertebrate animal in which the females carry the odd sex chromosome (in this case the W chromosome) has ever been recorded naturally producing viable WW offspring via a virgin birth.

“For decades WW has been considered non-viable” says Dr Booth. In such species, all known examples of babies that are the product of parthenogenesis are male, carrying a ZZ chromosomal arrangement.

Related: No sex for all-girl fish species – Virgin Birth for Another Shark Species – Bdelloid Rotifers Abandoned Sex 100 Million Years Ago – World’s Smallest Snake Found in Barbados – Androgenesis

World’s Smallest Snake Found in Barbados

Posted on August 4, 2008  Comments (3)

photo of Leptotyphlops carlae

The world’s smallest species of snake, Leptotyphlops carlae, with adults averaging just under 4 inches in length, has been identified on the Caribbean island of Barbados. The species — which is as thin as a spaghetti noodle and small enough to rest comfortably on a U.S. quarter — was discovered by Blair Hedges, an evolutionary biologist at Penn State.

Hedges determined that the Barbados species is new to science on the basis of its genetic differences from other snake species and its unique color pattern and scales. He also determined that some old museum specimens that had been misidentified by other scientists actually belong to this new species.

Scientists use adults to compare sizes among animals because the sizes of adults do not vary as much as the sizes of juveniles and because juveniles can be harder to find. In addition, scientists seek to measure both males and females of a species to determine its average size. Using these methods, Hedges determined that this species, is the smallest of the more than 3,100 known snake species.

According to Hedges, the smallest and largest species of animals tend to be found on islands, where species can evolve over time to fill ecological niches in habitats that are unoccupied by other organisms. Those vacant niches exist because some types of organisms, by chance, never make it to the islands. For example, if a species of centipede is missing from an island, a snake might evolve into a very small species to “fill” the missing centipede’s ecological niche.

In contrast to larger species — some of which can lay up to 100 eggs in a single clutch — the smallest snakes, and the smallest of other types of animals, usually lay only one egg or give birth to one offspring. Furthermore, the smallest animals have young that are proportionately enormous relative to the adults. For example, the hatchlings of the smallest snakes are one-half the length of an adult, whereas the hatchlings of the largest snakes are only one-tenth the length of an adult. The Barbados snake is no exception to this pattern. It produces a single slender egg that occupies a significant portion of the mother’s body.

Related: Smart Squirrels Sneaky Snake Strategy – posts on evolution – posts on reptiles – Evolution in Darwin’s Finches – cat spies snake
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Leopard Bests Crocodile

Posted on July 19, 2008  Comments (3)

photo of a leopard killing a crocodile

Leopard savaging a crocodile caught on camera:

A series of incredible pictures taken at a South African game reserve document the first known time that a leopard has taken on and defeated one of the fearsome reptiles. The photographs were taken by Hal Brindley, an American wildlife photographer, who was supposed to be taking pictures of hippos from his car in the Kruger National Park.

The giant cat raced out of cover provided by scrub and bushes to surprise the crocodile, which was swimming nearby. A terrible and bloody struggle ensued. Eventually, onlookers were amazed to see the leopard drag the crocodile from the water as the reptile fought back.

Eventually the big cat was able to sit on top of the reptile and suffocate it. In the past, there have been reports of crocodiles killing leopards, but this is believed to the first time that the reverse scenario has been observed.

Related: Water Buffaloes, Lions and Crocodiles Oh My – Far Eastern Leopard, the Rarest Big Cat – Leaping Tigress – Bornean Clouded Leopard

Mojave Desert Tortoises

Posted on June 19, 2008  Comments (1)

photo of desert tortoise

Mojave Desert Tortoises by Pelf Nyok:

But we were very lucky 🙂 We managed to see 5 desert tortoises (Gopherus agassizii) on that particular day, and one of them was spotted on the dirt road (not in the burrow)!

Desert tortoises are thought to live 40 – 60 years. They grow relatively slowly and adult females are larger than adult males (for obvious reasons). They typically breed from April to June and the female tortoises lay between 1 and 11 eggs. Incubation period for eggs varies from 80 to more than 100 days.

Pelf is experiencing a turtle conservation training and tour of the USA (see Turtle Camps in Malaysia). Her blog is doing a great job showing they made a good selection in choosing her for the scholarship.

Related: Ageless Turtles – Backyard Wildlife: Turtle – Long-Eared Jerboa

Alligator Blood Provides Strong Resistance to Bacteria and Viruses

Posted on June 15, 2008  Comments (1)

Gator Blood May Be New Source of Antibiotics

The study authors, from McNeese State University and Louisiana State University, said their research is the first to take an in-depth look at alligator blood’s prospects as an antibiotic source. According to the researchers, alligators can automatically fight germs such as bacteria and viruses without having been exposed to them before launching a defense.

For the study, the researchers extracted proteins known as peptides from white cells in alligator blood. As in humans, white cells are part of the alligator’s immune system. The researchers then exposed various types of bacteria to the protein extracts and watched to see what happened.

In laboratory tests, tiny amounts of these protein extracts killed a so-called “superbug” called methicillin-resistant Staphylococcus aureus, or MRSA. The bacteria has made headlines in recent years because of its killing power in hospitals and its spread among athletes and others outside of hospitals.

The extracts also killed six of eight strains of a fungus known as Candida albicans, which causes a condition known as thrush, and other diseases that can kill people with weakened immune systems.

Related: Entirely New Antibiotic Developed – Soil Could Shed Light on Antibiotic Resistance – articles on the Overuse of Antibiotics