Gene Duplication and Splicing Products for Hormone Receptors in the Central Nervous System Often Have Different Behavioral Effects

Parts of chromosomes may be duplicated as a consequence of the operation of genetic recombination machinery during the passage of chromosomal information from mother and father to offspring. They may end up in tandem positions on the same chromosome, or by the mechanisms of transposition, they may be moved to a different chromosome. It has been argued that such stochasticity represents a major driving force in evolution. This explains why mating behaviors are considered to be at the leading edge of evolutionary change. When one copy of the duplicated gene is subsequently altered, either of two consequences will occur. If the coding region is altered, the properties of the encoded protein may be changed. If the promoter of the gene is altered, the temporal and spatial patterns of expression and/or the physiological regulation of expression may be affected. This chapter focuses on the meaning of this train of events for hormone action.