Variation in male mate preference for female size in the swordtail Xiphophorus malinche M. Scarlett Tudor 1,2) & Molly R. Morris 1) ( 1 Ohio University, Department of Biological Sciences, Irvine 107, Athens OH 45701, USA) (Accepted: 18 September 2008) Summary Male and female mate preferences have the potential to influence one another, and such in- teractions could help explain variation in female mate preferences. In Xiphophorus malinche, larger females prefer asymmetrical males while smaller females prefer symmetrical males. We used a two-part preference test to determine if there were differences in mate preferences between symmetrical and asymmetrical males for female size that could influence female mate preference. We found no significant difference between symmetrical and asymmetrical male’s preferences. A preference for large female size was detected during the time males directly interacted with females and in standard dichotomous choice tests that followed, as long as the males had been isolated less than 30 days. We did detect variation in male pref- erence for female size depending on male size and the amount of time a male was isolated. These results suggest that variation in male mate preference is not likely to have produced the difference in female preference for symmetry between large and small females, but should be considered where females vary in their preference for male size. In addition, our results suggest that males may shift their preferences from large to small females depending on time since last mating opportunity. Keywords: male mate preference, symmetry, female size, variation in mate preference, Xiphophorus. Introduction Not all females prefer the same male or have the same strength of prefer- ence. Such variation in female mate preferences has been detected in a wide 2) Corresponding author’s current address: Department of Zoology, University of Florida, P.O. Box 118525, Gainesville, FL 32611, USA, e-mail: studor@ufl.edu © Koninklijke Brill NV, Leiden, 2009 Behaviour 146, 727-740 DOI:10.1163/156853909X446172 Also available online - www.brill.nl/beh