Strength of female mate preferences in temperature manipulation study supports the signal reliability hypothesis

Both sexually selected traits and mate preferences for these traits can be condition dependent, yet how variation in preferred traits could select for condition dependent preferences has rarely been examined. The signal reliability hypothesis predicts that mate preferences vary across environments in relation to the reliability of the information preferred traits provide in those environments. Extensive variation in the mc4r gene on the Y-chromosome that influences male size in Xiphophorus multilineatus allowed us to use a split-sibling design to determine if male size is more likely to provide information about male genotype (i.e., dam) when males were reared in a warm as compared to a cold environment. We then examined strength of preference for male size by females reared in the same two environments. We found that males were larger in the cold environment, but male size was more variable across dams and therefore a more reliable indicator of dam in the warm environment. Females rear..., Photos of all fish in study were taken to calculate growth rates by measuring their standard length (SL) in ImageJ (Rasband, W.S., NIH, Maryland, USA). Growth rate (GR) was calculated by subtracting the first SL measurement from the second SL measurement, and dividing by the number of days between the two measurements. Strength of preference (SOP) for females was calculated by subtracting the time she spent with the smaller animation from the time she spent with the larger animation. , ,