New Mexico whiptail lizard: Difference between revisions

The New Mexico Whiptail lizard (Aspidocelis neomexicana) cannot sexually reproduce because they are all females [1,2,3,4]. However, these lizards, simulate reproduction by way of pseudocopulation.  The whiptails of the genus Aspidocelis [5,6] are lizards, created by a hybridization of the western whiptail (A. Inornatus) [2,3,4] and the little striped whiptail (A. tigris). Generally, crossbred species (like the mule) are typically sterile. However, the New Mexico Whiptail reproduces by a complex series of events (that appear like cloning) where it's eggs require no fertilization, and its offspring are nearly a genetic duplicate of the mother [1, 5, 6].

An interesting fact that is a part of the process: two females will act out having sex as if one was a male. This is believed to increase the fertility of these lizards as it assists in producing more eggs than in females who don’t go through this act. The lizard who acts in the traditional female role assumes an inferior position to the other female lizard who assumes a superior position (hence the term pseudocopulation). Remarkably, the Whiptail lizards who assume the "female role" end up producing larger eggs than the lizard acting out the male role [1].  

Previously reptile researchers believed that the unfertilized eggs and hatchlings were clones of their mothers [2,3,4]. However, this has now been disproven. The internal self- fertilization that does occur, does NOT produce perfect offspring clones. Recent research by doctoral student Aracely Lutes at Baumann Lab demonstrated that the New Mexico Whiptail lizard produces two times the number of chromosomes as other types of Whiptail lizards which mate normally. Lutes discovered that, this occurs as a result of a " process of recombination of these chromosomes, somewhat similar to what happens in normal male/female pairings, which then produces genetically diverse offspring." [1]