May 23 2007
Marine biologists at the Queen's University of Belfast have made an interesting discovery: Hammerhead sharks will reproduce parthogenically under the right conditions. One of a number of female hammerhead sharks kept in captivity back in 2001 (yes, it took them this long to finish their research and publish) was reportedly able to produce young without the presence of a male hammerhead, which lead to some consternation. The original hypothesis was that the female in question had stored sperm from an earlier mating, so they took DNA samples from the sharks in the tank and the young and diff'd them to see which of the four was the mother and whether or not the DNA on file of male hammerheads could be identified.
They were quite surprised to find that there was no DNA characteristic of male sharks in the genome of the baby hammerhead.
This is a first in science, as far as anyone knows - vertebrates do not reproduce parthogenically, or at least we thought that they couldn't. Somehow, female hammerhead sharks are capable of inducing eggs to begin dividing and thus developing into young without the addition of male genetic material. The problem here is that it results in a loss of genetic diversity - without new genetic material from a male, the are only so many genes in a single sample that can be shuffled around, and this can reinforce drawbacks inherent in a particular specimen's genome.