Assessing Multiple-Paternity in the Green Lynx Spider Peucetia viridans
Authors:Cecilia Rangel-Garcia, Maria Shibatsuji
Mentor:Martina Ramirez, Professor of Biology, Loyola Marymount University
In prior studies, Ramirez et al. (2009, 2010) showed that mating copulatory plugs are not consistently produced after mating, which leads in some cases to multiple paternity in P. viridans broods. To better estimate the potential for multiple paternity in P. viridans, we are now genetically assessing whether the progeny data best fit with a single male as the father or not, based on the analysis of 18 females and their respective brood spiderlings and using genotypes at two variable allozyme loci [lactate dehydrogenase (LDH), phosphoglucose isomerase (PGI)]. We have examined three broods thus far and none have shown a significant deviation from a Mendelian genotype ratio for either LDH and/or PGI, given the adult female involved and her presumed male partner under a hypothesis of single mating. The low frequency of multiple paternity (2 of 12 broods) reported for this species by Ramirez et al. (2009), and by our current results, may be due to limited opportunities to encounter multiple male partners. Specifically, Arango et al. (2000) found that the female/male sex ratio shifted from 1:1.5 in April to 1:0.1 in September at a site in Mexico. Hence, females reaching adulthood later in the year may have had access to fewer males at her Mexican study site. If a similar seasonal sex ratio shift occurs in southern California, this may be partly responsible for the low frequency of multiple mating found by Ramirez et al. (2009) and in our current study.