The use of the mitochondrial cytochrome c oxidase subunit I (COI) gene to identify and discriminate spider species of eThekwini region.

Abstract

DNA barcoding compliments traditional morphology-based taxonomic approaches and is a molecular-based method for rapid species identification and flagging of potential new species. A fragment of 658-bp of the mitochondrial cytochrome c oxidase subunit I (COI) is used as the standard DNA barcode region for animals. While DNA barcoding has been applied with success across a wide range of eukaryotes, including spiders, in some animal groups, for example Diptera, COI has failed to reliably separate recognized species. This suggests that for particular groups DNA barcoding may not provide accurate species identification. Lack of gap between interspecific and intraspecific genetic distances complicates accurate species delimitation using DNA barcoding alone. This is particularly problematic when DNA barcoding is used differentiate among species which are closely related. The main aim of this study is to test the utility of COI to accurately discriminate among species of South African spiders collected from a small regional area and so we expect many of the species to be closely related. The study took place within the eThekwini municipality and surrounding areas. The municipality includes the city of Durban, and is situated within the globally-important Maputaland-Pondoland-Albany biodiversity hotspot. This region is characterized by a large human population (3.55 million) and a high rate of urbanisation (92%). In this study spiders (order Araneae) were chosen as indicators of diversity. Spiders are a hyper-diverse group of arthropods, with 40 000 species described world-wide. There are currently, 2 170 described species from 71 families recorded from South Africa, but this number is expected to rise as additional species continue to be described. Spiders are important as bioindicators, and have been used to study the effect of urbanisation on biodiversity. In this study DNA barcoding is used to aid in the rapid identification of spider species. By using the DNA-based tool, the effect of urbanisation on spider species diversity along an urbanisation gradient will be assessed. The study also intends to design and test the utility of mini-barcodes for species identification when the full DNA barcode region cannot be amplified i.e. when DNA is degraded.