Toronto Zoo announces three baby Desert Grassland Whiptails hatched on Saturday, January 2, 2016 making all three females the official first births of the new year! The babies are not viewable by the public at this time, but their mother shares an exhibit with another desert lizard species, the San Esteban Chuckwalla, in the Zoo's Americas Pavilion. Did you know? Desert Grassland Whiptails reproduce by parthenogenesis, meaning there is no sexual reproduction because this species contains only females!
What occurs is this: Meiosis is a process of cell division that produces gamete cells (sperm and eggs). Whiptails are a triploid species meaning they have three sets of chromosomes compared to most animals that have only two sets. Even though they reproduce by parthenogenesis without mating with a male, the offspring do not necessarily have identical chromosomes as their mother. When the female lizard is forming gametes (eggs), she doubles the sets of chromosomes to six. To maintain genetic diversity they pair sister chromosomes (one chromosome from each new pair) instead of pairing homologous chromosomes from each parent chromosome during meiosis to form the gamete.
An interesting aspect to reproduction in these lizards is they demonstrate many characteristics of sexual behavior, including courtship and pseudo-copulation even though they are all females. One female plays the role of a male and mounts the female that is about to lay eggs. This behaviour is due to hormonal cycles. It has been found that lizards who act out the courtship ritual produce more offspring, therefore it can be said that they still require sexual behaviour to maximize reproductive success. Now you know!
Whiptails that are captured by the tail will shed part of the tail structure and thus be able to flee. The detached tail will continue to wiggle, creating a deceptive sense of continued struggle and attracting the predator's attention away from the fleeing prey animal. The animal can partially re-grow its tail over a period of weeks. The technical term for this ability to drop the tail is caudal autotomy. Now that's a defence mechanism!