Dragon virgin births startle zoo keepers
Non-sexual reproduction could lower the fitness of captive animals.
A nativity story with a twist is playing out this Christmas in two zoos in the UK. At Chester Zoo, a Komodo dragon named Flora awaits the birth of eight babies, and another four dragons have already hatched at London Zoo — each and every one the product of a virgin conception.
Read the story here.
Comments
We also have a recent virgin birth of a lovebird at out house. We own a female lovebird who is five years old. She has not been with another bird since we got her five years ago, and she has never been outside. On November 29 we found a baby bird in her cage. Mom and baby are fine so far. for a picture, email me at esmcculloch@aol.com. This bird was seriously stressed by the Hurricane Katrina, and we believe that may have had a role. We have not been able to find anyone who knows how frequently this occurs in lovebirds.
Posted by: ella s mcculloch | December 21, 2006 06:38 PM
Brad Shaffer, a professor of evolution and ecology at UC Davis who studies the evolution and genetics of reptiles and amphibians, says that there are several examples of "virgin birth" or parthenogenesis in other lizards and snakes, but not in the family of lizards to which Komodo dragons belong.
Most of these examples are fast-spreading "weed species," such as house geckos in Hawaii or the web-tail lizards in the American Southwest. They are typically hybrids that lose the ability to reproduce sexually and can only reproduce in this way.
Parthenogenesis allows for a rapid increase in numbers, Shaffer says. All the individuals in the population can produce young, "and you don't waste time making males."
But reproducing without sex has long term costs because there is no shuffling of genes between generations and harmful mutations can build up.
There is some evidence from zoos that reptiles housed in captivity for a long time can spontaneously produce fertile eggs, Shaffer says, citing work especially by Gordon Schuett at Arizona State University. A case was reported in a Burmese python in a Dutch zoo in 2003. But many reptiles can also store sperm for long periods of time, and researchers would need to check carefully that the animals had never, even accidentally, been in contact with another male of the same or a related species. Careful genetic analysis is needed to show that the offspring come only from the mother.
Shaffer adds: "Whether or not this represents an adaptation to island living in Komodo dragons is an interesting question. However, given the genetics of sex determination in these lizards, where the heterogametic sex is the female, the story seems to be that all kids from parthenogenetic births are males, so that would imply that it is a one-generation only phenomenon."
Posted by: Andy Fell | December 21, 2006 10:15 PM
This is a fascinating story - too bad it's behind a pay wall where no one can read it.
Luckily it's been widely covered, including by the good folks at Scientific American. (Strange that their news appears on the homepage of this very site, yet they have such different policies about access to their content... ;)
http://sciam.com/article.cfm?chanId=sa003&articleId=C61B0F6E-E7F2-99DF-3BB99A2F0F7F8802
Posted by: Christopher | January 2, 2007 04:44 AM