A Description of Variation in Fecundity Between Two Populations of Wolf Spider Rabidosa rabida in Searcy Arkansas Using Brood Size Measurements

Abstract

Fecundity, a very important population variable, can be estimated by measuring the number of juveniles hatching out of individual egg sacs. Rabidosa rabida is a large wolf spider that is common in Arkansas and much of the eastern portion of North America. This study attempts to expand previous estimates of variation in fecundity made for this species by Reed and Nicholas in Mississippi. In an attempt to determine baseline variation in a common arthropod predator, we hypothesized that a significant variation would be found in fecundity estimates between two populations of R. rabida in Arkansas. We also hypothesized that this variation would be similar to the variation reported in Mississippi. Two populations of R. rabida were collected in late August and early September of 2016. The egg sacs were allowed to hatch while both the mothers and juveniles were placed in alcohol, with the exception of twenty from each mother which were photographically measured. A comparison was made between the two populations and between variation measured by Reed and Nicholas. We found significant variation between brood size of the two populations in Arkansas similar in magnitude to what was found in Mississippi. We did not find any significant difference in size of juveniles or mothers between the two locations similar to what was found in Mississippi. Observing patterns in these traits provide a starting point for comparison to future measurements which may aid in quantifying differences in populations. A lack of descriptive data for arthropod species has been a challenge in ecological and conservation studies.