Abstract
M.Sc. (Environmental Management)
Alien species have unaffordable economic and ecological consequences in their recipient environments. These consequences are now a major concern globally. However, the debate today evolves around which approach is most suitable for a better answer to the invasion threats. Here, the present mini-dissertation first presented basic background on biological invasions including some of the most tested hypotheses in the field. Then, summarized existing approaches specifically in South Africa to combat invasive alien species. As reported in the present document, it is noted that none of these approaches has been effective pointing perhaps to the complexity of biological invasion. In this regard, the present study proposed a continued commitment towards the search for statistical or mathematical models of invasion to complement existing approach in South Africa. Furthermore, the present study revisited a recent study that investigated the predisposition of alien mammals to various invasion intensity in South Africa. In that study, categorical ordinal response variable (here invasion intensity) were simply converted into numerical values. Here, this approach was questioned, and the same dataset was reanalysed using the cumulative link mixed effect model based on 44 explanatory variables. The results confirms some of the correlates of invasion intensity previously reported (social group size, gestation length, and evolutionary distinctiveness). In the meantime, some other variables previously reported as significant correlate are no longer so (latitude, human population density). Perhaps more interestingly, a new correlate, i.e. basal metabolic rate, is now found as significant correlate of invasion intensity in South Africa with the highest predictive power. Cumulatively, the findings reported in this project suggests the need for using appropriate analytical approach and provides an update of ecological and evolutionary predisposition of alien mammals to invasion in South Africa.