FGFR1 and Kallmann syndrome: For instance the Kallman syndrome in humans is caused by a knockout of FGFR1 (which encodes fibroblast growth factor receptor 1) (Muenke et al., 1994), industrial melanism in British peppered moths is caused by a single gene mutation (van’t Hof et al., 2011), and natural variation in the npr-1 gene in the nematode Caenorhabditis elegans is a major determinant of multiple life-history traits (Andersen et al., 2014; Sterken et al., 2015).