Presentation Title

Genetic Variation and Biogeography of the Silver Garden Spider Argiope argentata (Araneae: Araneidae)

Faculty Mentor

Dr. Martina Ramirez

Start Date

17-11-2018 8:30 AM

End Date

17-11-2018 10:30 AM

Location

CREVELING 113

Session

POSTER 1

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

In a study of the phylogeny and biogeography of the fossorial coastal dune spider Lutica, Ramirez & Beckwitt (1995) found that the mainland populations of new species A and B are only about 57 km apart at their southern and northern boundaries respectively [between La Jolla Beach, Ventura County and the Ballona Wetlands, Los Angeles County], yet spiders from these regions are members of different taxa. To determine if the north-south disjunction is also seen in other southern California spiders, this study is investigating the genetic differentiation and biogeography of silver garden spiders (Argiope argentata), a species whose distribution includes coastal populations both north and south of the Ballona Wetlands. This is being accomplished by the genetic characterization of spider samples from A. argentata populations from Ventura County to San Diego County, using allozyme electrophoresis as the molecular assessment technique, given its cost-effectiveness for large samples. During 2015 & 2016, Spider Lab students sampled 550 A. argentata at 13 sites, ranging from Leo Carrillo State Park, Los Angeles Co., to Sunset Cliffs Natural Park, San Diego Co. Thus far, 307 of these spiders have been genotyped for variation at 9 enzyme loci. Of these, the AAT-B locus displays a regional pattern, with allele A very common in most populations south of Palos Verdes Drive South (PVD. Los Angeles Co.) and allele C being common at PVD and most populations to the north. This pattern may reflect the influence of the historic north-south biogeographic disjunction noted by Ramirez & Beckwitt (1995).

Summary of research results to be presented

As of the summer of 2018, 307 spiders out of the 550 spiders collected back in 2015 and 2016 have been genetically processed. Data has been subject to a phylogenetic analysis which illustrates three genetically different groups. Results indicated our north-south of the Sand Gorgonio Barrier to be genetically different. There is a third genetically distinct group, which is our most northern location, Leo Carrillo and Point Dume State Park which is unknown why this group is genetically different from the rest.Previous research conducted by Ramirez & Beckwitt in 1995 found Lutica spiders to also be genetically different in the north-south region of the San Gorgonio Barrier as well (Ramirez & Beckwitt et al. 1995). Research conducted by Sullivan & Best found kangaroo rats were genetically affected by the San Gorgonio Barrier (Sullivan & Best et al. 1997). Future experimental focus: Continue genetic analysis of remaining 318 spiders and continue to look for north-south disjunction shown in the phylogenetic analysis. We would also like to future investigate the catalyst for the genetic differences seen in the spiders from the Leo Carrillo and Point Dume State Park.

This document is currently not available here.

Share

COinS
 
Nov 17th, 8:30 AM Nov 17th, 10:30 AM

Genetic Variation and Biogeography of the Silver Garden Spider Argiope argentata (Araneae: Araneidae)

CREVELING 113

In a study of the phylogeny and biogeography of the fossorial coastal dune spider Lutica, Ramirez & Beckwitt (1995) found that the mainland populations of new species A and B are only about 57 km apart at their southern and northern boundaries respectively [between La Jolla Beach, Ventura County and the Ballona Wetlands, Los Angeles County], yet spiders from these regions are members of different taxa. To determine if the north-south disjunction is also seen in other southern California spiders, this study is investigating the genetic differentiation and biogeography of silver garden spiders (Argiope argentata), a species whose distribution includes coastal populations both north and south of the Ballona Wetlands. This is being accomplished by the genetic characterization of spider samples from A. argentata populations from Ventura County to San Diego County, using allozyme electrophoresis as the molecular assessment technique, given its cost-effectiveness for large samples. During 2015 & 2016, Spider Lab students sampled 550 A. argentata at 13 sites, ranging from Leo Carrillo State Park, Los Angeles Co., to Sunset Cliffs Natural Park, San Diego Co. Thus far, 307 of these spiders have been genotyped for variation at 9 enzyme loci. Of these, the AAT-B locus displays a regional pattern, with allele A very common in most populations south of Palos Verdes Drive South (PVD. Los Angeles Co.) and allele C being common at PVD and most populations to the north. This pattern may reflect the influence of the historic north-south biogeographic disjunction noted by Ramirez & Beckwitt (1995).