Meeting Abstract
106.3 Tuesday, Jan. 7 08:45 Female Fitness as a Function of Stored Sperm in the Livebearing Western Mosquitofish, KROH, GE*; DEATON, PR; JOHNSON, DR; St. Edward’s University, Austin TX ; St. Edward’s University, Austin TX ; St. Edward’s University, Austin TX gretchkroh@gmail.com
Females in promiscuous mating systems can use sperm storage as a mechanism of post-copulatory sexual selection to preferentially choose sperm and to give birth to multiple broods before mating again. In coersive mating systems, sperm storage can evolve in females to decrease the fitness costs of mating. Interbrood interval (IBI; the time period between two different broods), number of offspring per brood, female body fat composition, gonadosomatic index (GSI; measure of energy allotted to reproduction) and number of broods produced are all factors that can affect female fitness by suggesting the length of time a female can store sperm and the quality of sperm. , an invasive live bearing fish, was studied due to its ability to store sperm, the natural abundance of the species and the ease at which it can be studied in the laboratory. We examined the above variables resulting from stored sperm of female . We investigated 10 females from each treatment (0,1,2, or 3 males) over the breeding season (March to November). We predict for females relying solely on stored sperm that 1) brood number and number of neonates are inversely related; 2) IBI will remain constant and 3) GSI and body fat composition will be low. For females mated with males, we predict 1) brood number will increase due to presence of males; 2) number of offspring should remain constant; and 3) GSI and body fat composition will be high. IBI remained constant across treatments while mean number of neonates and number of broods was significantly different between the 0 and 2 male treatments (p=0.008 and p= 0.006 respectively). GSI was most variable for females in the 0 and 3 male treatment. These results provide a comprehensive understanding of sperm storage in promiscuous mating systems.
