Monday, 28 May 2007

Men, can live with them, can live without them

Sex is not necessary for all members of the animal kingdom. Of course it has its advantages, primarily, combining genetic material adds to the diversity of a species and makes it more ‘hardy’. But in vertebrates, organisms that are considered ‘more complex’ (ie. fish, amphibians, reptiles, birds and mammals) asexual reproductions is extremely rare and is thought to be limited because of the complexity of vertebrate genetics and body plans.

Recent discoveries has defied this logic however. A captive female hammerhead shark had a ‘virgin’ birth. The shark, which lives at Henry Doorly Zoo in Nebraska gave birth to a pup despite having had no contact with a male. A similar incidence was reported of a komodo dragon in Chester Zoo in the UK.

Originally it was thought that the females were storing sperm from a previous encounter for an extended length of time but genetic tests have now confirmed that the offspring share their DNA with only individual, their mother. This type of reproduction is known as parthenogenesis and it not entirely clear how or why it developed. One theory suggests that it evolved as a mechanism to deal with times of isolation. For example, if a komodo dragon found itself on an island without a mate, a few offspring could be produced while it waited for another komodo dragon to arrive and the population could be sustained until a viable breeding pool arrived.

This new ‘twist’ has created many questions including what other animals are capable of reproducing in this fashion. So far the ability has not been documented in mammals and birds but it has only been with the recent advent of genetic testing that such unusual cases can be investigated.

Friday, 25 May 2007

Only in America....

Ok this is off topic but I found this article too funny not to mention.

Only in America can I guy openly surf for pornography at his workplace, be warned against the behaviour and then, when he is fired, turn around and sue the company for $5 million USD for wrongful dismissal. Apparently he is arguing that he was 'self-medicating' for his sex addiction.

No matter what you say, I still think humans have the oddest sexual behaviour:)

Lovesick albatross still looking for romance after 40 years

Albert, a lovesick albatross was blown off course 40 years ago and has been living in Scotland since 1967. Over the last four decades he has been wooing gannets, in his desperate search for a mate. But being 8,000 miles away from his natural breeding ground, he has been unsuccessful in finding a suitable partner. Albert’s natural home is in Southern Argentina and the Falkland Islands. Read more about Albert at the BBC website.

Thursday, 24 May 2007

Gay flamingos pick up chick

Carlos and Fernando, a pair of gay flamingos have adopted an abandoned chick. Zoo staff say they have been desperate to start a family, even chasing other flamingos from their nests to steal their eggs at the Wildfowl and Wetlands Trust (WWT) in Slimbridge near Bristol.

And so they were chosen as adoptive parents for an unhatched egg when a nest was abandoned. The males have the ability to feed chicks by producing milk in their throats.

The couple has been together for six years and WWT spokeswoman, Jane Waghorn, says "Gay flamingos are not uncommon. If there aren't enough females or they don't hit it off with them, they will pair off with other males."

Wednesday, 23 May 2007

Ever wondered how dinosaurs… er…you know…did it?

Check out this discussion between expert biologists and palaeontologists at the Ask a Biologist website about the latest theories on dinosaur sex, from balancing sauropods to spiny stegosaurs.

Tuesday, 22 May 2007

Bats: More brain than brawn?

Brains or brawn, which is more important? Can you have both? Well not if you’re a male bat. A recent study has shown a negative correlation between brain size and testicle size in bats; so for bats, intelligence comes at a steep price.

One theory is that the development of a large brain or large testicles is ‘expensive’ so bats can’t afford both.

Scott Pitnick, of the Syracuse University in New York conducted the research and says "The male who ejaculates the greatest number of sperm may win at this game, and hence many bats have evolved outrageously big testes. Because they live on an energetic knife-edge, bats may not be able to evolutionarily afford both big testes and big brains."

Females bats of many species mate with more than just one male and can store their sperm, leading to fierce competition. Pitnick believes that there is an important link between fertility and testicle size. After analysying 334 species of bats, Pitnick’s team found that in species with promiscuous females, males had evolved larger testicles and had relatively small brains. In species where the females were faithful to their mates, the correlation was reversed. Interestingly, male fidelity appeared to have no link to testicle or brain size.

In some bat species, the males' testicles can be as much as 8.5% percent of its body mass. In contrast, primates' testicles (including humans) is less than 1% of body mass.

Thursday, 17 May 2007

Lonesome George still a devout bachelor

Lonesome George, a giant Galapagos tortoise and mascot for conservation is the last of his kind. George has long chosen been a dedicated bachelor, even when given his chosen of female mates from a closely related species. Hopes rose last week when a hybrid tortoise was found last week, but unfortunately this animal is also male, so it has not changed the fact that George is unlikely to settle down and start a family anytime soon.