Reinforcement is a process hinted at by Alfred Russell Wallace and first described in detail by Theodosius Dobzhansky.  It is the evolution of increased pre-zygotic reproductive isolation driven by partial post-zygotic isolation between nascent species.  It is often viewed as “completing” the process of speciation.  Historically, it has been a controversial process, and evidence supporting its operation is largely circumstantial.

We have recently documented the operation of reinforcement in Phlox drummondii, in which populations growing sympatrically with P. cuspidata exhibit divergence in flower color, which reduces inter-specific pollen flow.  For more information see the following publications:

Hopkins, R., and M. D. Rausher.  2012. Pollinator-mediated selection on flower color allele drives reinforcement.  Science 335: 1090-1092. [Download PDF File]

Hopkins, R., and M. D. Rausher.  2011.  Identification of two genes causing reinforcement in the Texas wildflower Phlox drummondii.  Nature 469: 411-415. [Download PDF file]