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).

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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).