Meeting Abstract

52.4  Sunday, Jan. 5 11:00  Body condition affects ejaculate traits in a lizard with condition-dependent fertilization success KAHRL, A.F.*; COX, R.M.; University of Virginia afk7df@virginia.edu

Sexual selection is predicted to deplete genetic variation in fitness-related traits, but condition-dependence can maintain phenotypic variation in the face of strong selection. Characteristics of the male ejaculate, such as the quantity or quality of sperm, can be both condition-dependent and subject to strong sexual selection. Because sperm production can be energetically costly, males are predicted to respond to limited resources by reducing the quantity or quality of their sperm. We tested the condition-dependence of ejaculate traits by experimentally altering body condition through food restriction in the lizard Anolis sagrei, which has condition-dependent fertilization success. As predicted, food restriction reduced male body condition and decreased total sperm production relative to males fed ad libitum. Additionally, sperm morphology within individuals was more variable in food-restricted males, suggesting that energy limitation detrimentally impacted both the quality and quantity of sperm. Food restriction also increased the size of the sperm midpiece, suggesting a possible tradeoff between sperm quality and quantity under energy limitation. Because these ejaculate traits are potentially related to sperm competitive ability and fertilization success our results suggest that condition-dependence may be important for male fitness and the evolution of sperm morphology.