Assessing the risk of non-native small mammals in the South African pet trade.
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Date
2021
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Abstract
Humans have introduced non-native small mammalian species for various purposes, including
hunting, biological control, farming, fur markets, ornamental, and pet trade. The latter has been
cited as one of the main invasion pathways for some small mammals through accidental
escapes and intentional releases of pets. In addition, the pet trade has been cited as one of the
major threats to biodiversity loss and human health through the spreading of zoonotic diseases.
The trade of non-native pets is growing in South Africa, and this is of great concern as some
of these species may become invasive should they escape or be released from captivity. There
is also a lack of information regarding which non-native small mammalian species are sold in
South Africa. As a result, two primary sources of trade (online and pet shops) were assessed to
determine the extent of small mammal trade in South Africa. A list of the traded small
mammalian species was compiled online and physical pet shops to determine which species
pose an invasion risk and have potentially high impacts. Mitochondrial gene regions were used
to assess the taxonomy and genetic diversity of 156 rodent specimens collected in the South
African pet shops. We also determined if their genetic diversity follows a geographically
correlated pattern.
A total of seven websites and 122 pet stores in South Africa were recorded, with 24
non-native small mammalian species traded. Three provinces, Gauteng, Western Cape and
KwaZulu-Natal, had the highest number of websites and pet shops selling these species.
Overall, online trade had more species diversity when compared with pet shops. Rodents and
primates dominated the trade; however, the European rabbit Oryctolagus cuniculus, guinea pig
Cavia porcellus, Norwegian rat Rattus norvegicus and house mouse Mus musculus were the
most available species in both online and pet shops. In terms of the potential impacts, traded small mammalian species were associated with
both socio-economic and environmental impacts. Impacts on agricultural and animal
production (livestock) prevailed for the socio-economic category, while the impacts on animals
(predation) and competition were the main mechanisms in the environmental impacts. Of the
species recorded, 14 had potential climatic suitability; however, species such as Guinea pig
Cavia porcellus, sugar glider Petaurus breviceps, domesticated ferret Mustela putorius furo,
M. musculus, O. cuniculus, European grey squirrel Sciurus carolinensis, and R. norvegicus are
likely to become invasive given their popularity in the trade, large climatic suitability, and
history of invasion through releases and accidental escapes.
A total of 156 rodent samples were identified using molecular analyses, with 115
specimens identified as M. musculus, 35 as R. norvegicus and six as Southern multimammate
mouse Mastomys coucha. Phylogenetic trees showed that the three species were monophyletic,
and there was a genetic diversity within M. musculus and R. norvegicus. The specimens for M.
musculus and R. norvegicus were more geographically diverse when compared with the
specimens for M. coucha. As a result, this suggests that most of the provinces comply with the
trade regulations as native species are prohibited from trade. The combined data recovered 19
unique haplotypes for M. musculus and eight haplotypes for R. norvegicus. However, the
genetic diversity for M. musculus did not show a clear geographical pattern, while R.
norvegicus showed a subtle geographic structure. Unique haplotypes in these species may be
explained by the desire to breed rare varieties or introduce new strains from different pet trade
sources. In conclusion, small mammalian species with high trade volume, suitable climate,
potential environmental and socio-economic impacts are likely to become invasive and cause
impacts in South Africa. In addition, M. musculus and R. norvegicus individuals may establish
feral populations if released from captivity, given that their haplotypes were unique. Therefore, it is recommended to further monitor the pet trade (both online and physical pet shops), including surveillance, to determine if there are any escapes and releases from the trade.
Description
Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.