Assessing Multiple-Paternity in Broods of the Trapdoor Spider Bothriocyrtum californicum
Authors:Therese Blanch, Gabriela Lopez
Mentor:Martina Ramirez, Professor of Biology, Loyola Marymount University
In a recent genetic study, Ramirez et al. (2013) found no evidence for inbreeding in B. californicum populations, despite the potential for adult males to mate with siblings and other relatives in their natal area. Since multiple mating by females is one way to avoid the costs of inbreeding, we are looking for evidence of multiple paternity in B. californicum broods. In 2012-2013, we gathered five B. californicum broods and their mothers from Kenneth Hahn State Recreation (SRA). Brood size was 67-167. In summer 2013, we genotyped each set of mothers and 50 spiderlings per brood for variation at the phosphoglucomutase (PGM) locus. One mother and her brood were all of the same genotype (AA), making them unusable for paternity assessment. Of the four other sets of mothers and broods, three showed a significant deviation from a Mendelian genotype ratio, given the adult female involved and her presumed male partner under a hypothesis of single mating. This is evidence that field-collected B. californicum females frequently mate with multiple male partners. During the balance of 2013, we will continue to search for additional sets of mothers and broods from Kenneth Hahn SRA, so as to expand our sample size for genetic analysis.