Baumann Laboratory

 

Parthenogenesis

 

Parthenogenesis is a mechanism in which offspring are produced asexually.  Lineages are generally comprised of all females and in theory, these species should have an advantage over their sexual counterparts because (1) there is no energy expended in searching for a mate and (2) each individual is capable of reproducing, so no energy is wasted on males in general.  However, in reality, this does not appear to hold true since sexual reproduction is the most common form of reproduction among animals.  Therefore sexual reproduction must provide substantial advantages to the organism in order to compensate for the increased energy required to produce males.

An obvious advantage for sexual reproduction is the genetic diversity that results from the combination of gametes.  This increased variation in sexual species allows for different selective advantages among individuals that aid in the long-term survival of the species.  In contrast, parthenogenotes are thought to be genetically isolated and clonal, decreasing their chances for long-term survival in a changing environment.

In the laboratory, we are particularly interested in the mechanism of parthenogenesis at the molecular level.  How are gametes produced that have the same chromosome complement as the somatic cells of the mother?  Is there genetic diversity among individuals?  What events trigger parthenogenesis in species that normally reproduce sexually?

Our model organisms are lizards of the genus Aspidoscelis, commonly referred to as whiptail lizards.

 

A. tesselata (parthenogenetic)

 

A. tigris (sexually reproducing)