Genetic diversity of edible Lepidoptera in Southern Africa and implications for sustainable use of wild populations
Date
2024-03
Authors
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Journal ISSN
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Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: The African Saturniidae encompass 400 species, some of which contribute significantly to the
nutrition and
income of many rural livelihoods across the continent. Due to their significance, species such
Gonimbrasia belina are subjected to unregulated harvesting and hostplant destruction which threaten
their populations. The taxonomic classification of Saturniidae is challenging, impeding accurate
documentation of the biodiversity in this family. Additionally, genetic data that could guide
conservation and management efforts of Saturniidae in the wild is largely unavailable. Our study
aimed to address these knowledge gaps by pursuing four primary objectives.
Firstly, we generated DNA barcode (COX1) data for 17 species to contribute to cataloguing the
biodiversity of African Saturniidae. The genetic diversity of 170 specimens representing 17 species
across 12 genera was assessed in the context of 1586 DNA barcodes publicly available for those
genera. Results show that the current taxonomy of African Saturniidae for the 12 genera is affected
by taxonomic inconsistencies and clerical errors resulting in 56% of cases of non-monophyly.
Integrating alpha taxonomy and genetic data resolved 87% of these cases, thus demonstrating the
importance of combining the two disciplines.
Secondly, in the context of the mitochondrial phylogeny of the family, Africa was represented by
only two species (Gonimbrasia belina and Gynanisa maja), a small number relative to the Asian
counterparts. We generated complete mitochondrial genomes for 12 African Saturniidae from five
tribes, including the first representatives of the tribes Eochroini and Micragonini. We performed
comparative mitogenomics and phylogenetic reconstruction of the family, which strongly supported
the monophyletic tribal structure in Attacini, Bunaeini, Micragonini and Saturniini, the sister
relationship between Saturniini and Attacini, and the placement of Eochroa trimenii in the tribe
Eochroini.
Thirdly, despite the extensive harvesting of edible caterpillars of Saturniidae across southern
Africa, genetic data for informing conservation and management of these species is largely lacking.
We assessed the phylogeography, genetic diversity and historical demography of Gynanisa maja in
northwestern Namibia based on sequence data for the standard DNA barcoding region (COX1) and two
mitochondrial polymorphic (ND6 and Cytb). This baseline data showed that Gy. maja in northwestern
Namibia is genetically diverse and panmictic, indicating healthy levels of genetic diversity and
demographic status.
Lastly, we evaluated the phylogeography, genetic diversity and demographics of Gonimbrasia belina
using a multi-marker approach (mitochondrial sequences and nuclear RADseq data). Gonimbrasia belina
exhibited high overall genetic diversity and showed large scale phylogeographical structure between
Namibia and the South Africa/Botswana region. Some level phylogeographic structure was also
apparent at the fine scale, with a large proportion of haplotypes exclusive to Botswana or South
Africa, and shared haplotypes present at the border between the two countries. Furthermore, G.
belina showed signs of strong population
structure, low genetic diversity, small effective population size and recent bottlenecks across
individual
sampling sites in Botswana and South Africa, raising conservation concerns.
Overall, our study offers important baseline contributions for species identification, genetic
characterization, and conservation strategies of African Saturniidae, particular the edible species G. belina and Gy. maja.
Description
Thesis (PhDAgric)--Stellenbosch University, 2024.