Ecological speciation is the consequence of reproductive isolation arising from divergent adaptation to different ecological niches. The parallel evolution of stickleback species-pairs provides an excellent opportunity to identify the environmental and molecular mechanisms that influence this evolutionary process. Through laboratory and field studies of hybrid zones between marine-freshwater species-pairs, Dr. Jones has studied potential pre- and postmating reproductive barriers and found postzygotic environmentally-dependent genetic effects leading to reduced overwinter survival of hybrids to be a major factor.