Insects provide essential ecosystem services such as pollination, pest control, and decomposition, but there is concern that insect abundance is rapidly declining. However, identifying insect biodiversity trends in South Africa is challenging because of the lack of baseline data for most regions, and most insect species still remain undescribed. This knowledge gap also limits our ability to understand how insects interact with plants and other organisms, interactions that are fundamental to ecosystem functioning. Despite being one of the most biodiverse countries globally, South Africa also suffers from a shortage of taxonomic expertise, further limiting efforts to document and monitor its insect diversity. There is, therefore, an urgent need for tools that can fill these gaps quickly and consistently. DNA barcoding — a technique that uses short DNA sequences to identify species — has proven to be an efficient way to generate biodiversity data.
In this thesis, I critically review South Africa’s contribution to insect DNA barcoding and found five insect orders (Hymenoptera, Diptera, Thysanoptera, Plecoptera, and Strepsiptera) which have a greater number of genetic species proxies than described species. I collected data from 22 Malaise traps spread across 11 different National Botanical Gardens (NBG) and used DNA barcoding to document the insect diversity within them. I contributed 337,809 new insect specimens and 29,919 unique insect species proxies to the Barcode of Life Data System (BOLD) database. By contrasting plant and insect diversity across National Botanic Gardens, I showed that plant species richness does not predict insect species richness, but that plant phylogenetic turnover has a strong relationship with insect phylogenetic turnover...
- Using DNA barcoding and machine learning to investigate macroecological relationships between plants and arthropods across South Africa
- Ross Dylan Stewart
- Michelle Van Der Bank
- University of Johannesburg; Doctor of Philosophy (PHD)
- Doctor of Philosophy (PHD), University of Johannesburg
- 9963204907691
- University of Johannesburg
- University of Johannesburg; Department of Botanical and Plant Bio-Technology; Faculty of Science
- English
- Dissertation