Meeting Abstract
Individuals may alter their reproductive investment depending on the type of environment they encounter. Females experiencing stressful conditions might opt to alter sex ratios of litters or invest more into current rather than future reproduction. In the context of parasitism, these effects could manifest as parasitized mothers producing more female offspring, as in the Trivers-Willard Hypothesis, or producing offspring that reach maturity quickly. Our goal was to determine if infestation by fleas Xenopsylla ramesis and Parapulex chephrenis altered sex ratio, number of offspring, or litter quality in two rodent species: Meriones crassus and Acomys caharinus. Further, flea infestations included characteristic fleas and non-characteristic fleas to determine if number and type of fleas significantly altered host reproductive investment. We found no effect of infestation on sex ratio for either rodent species and no effect of infestation on litter mass, litter size, or pup mass gain in A. caharinus. However, treatment did have an effect on litter mass in M. crassus. Further, a significant interaction between treatment and litter size on pup mass gain in M. crassus indicated that small, parasitized litters gain the most mass. These results suggest that, at least in M. crassus, infested mothers produce offspring that mature more quickly but do not alter sex ratio of their litters in response to infestation. Thus, mothers may invest more in current reproduction when subjected to the stresses of parasitism.
