| Summary: | Invasive species are regarded as one of the top five leading causes of the global extinction crisis. The majority of threatened species recovery plans therefore call for lethal control of invasive species, particularly predators. Vast resources are expended to combat the threats posed by invasives, and considerable research efforts have been devoted to developing best practice pest control practices; with little success overall. The reason for this may be that although invasive species cause extinctions, they are not the ultimate cause. Instead, the shift to invasive-dominated states is driven by an underlying loss or lack of ecological resilience. One of the leading processes that might result in widespread resilience loss, and release of invasive species, is the control or absence of apex predators. Across the globe, and in every habitat investigated, apex predators play a keystone role in enhancing ecological resilience to the damaging influence of environmental perturbations. I tested the hypothesis that state shifts to invasive dominance are symptomatic of the disruption of top-down regulation, and that ecological resilience is largely determined by the social stability of apex predators. Australia presents a unique opportunity to examine these ideas because it is here that mammalian invasions and extinctions have been most severe; pest control is intensive and widespread; and only a single large mammalian predator, the dingo (Canis lupus dingo), is extant. I studied the interactions between dingoes, invasive mesopredators, herbivores, small mammals and vegetation in a series of sites across the arid zone, representing different levels of predator control (poison-baiting). Four of the sites were monitored over 2-3 years to study the effects of predator control cessation and intensification. This study was therefore conducted on both a spatial and temporal scale, providing not only correlative, but also (quasi) experimental evidence from large-scale predator manipulations. The results of this study indicate ...
|
|---|