1 1 Cryptic Genetic Variation Can Make Irreducible Complexity 2 a Common Mode of Adaptation 3 Authors: M.V. Trotter 1,3 , D.B. Weissman 2 , G.I. Peterson 3 , K.M. Peck 3,4 , J. Masel 3* 4 Author Affiliations: 5 1 Department of Biology, Stanford University, Stanford, CA, USA 95306. 6 2 Institute of Science and Technology Austria, Klosterneuburg, Austria 7 3 Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA 8 85721. 9 4 Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA 10 27599. 11 *Corresponding author: masel@u.arizona.edu, 520 626 9888 12 Other emails (in order): mtrotter@stanford.edu, dbw@ist.ac.at, gpeterson81@gmail.com, 13 kaylap@live.unc.edu 14 15 Running title: Complex adaptation via crypticity 16 Keywords: Complex adaptation, adaptive valley, evolutionary capacitance 17 Words: 4,500 18 Figures: 3 19 Supporting Information: 5 Figures 20