The article by Euan Ritchie and C Johnson reviews the roles of predators, particularly apex predators, in regulating ecosystems and biodiversity. Apex predators, which are typically large and specialized hunters, play a crucial role in controlling smaller 'mesopredators' through intraguild interactions. The removal of apex predators can lead to mesopredator outbreaks, resulting in increased predation on smaller prey species. The suppression of mesopredators by apex predators is widespread and can have significant impacts on biodiversity. Apex predators control mesopredators through direct lethal encounters and fear-induced changes in behavior and habitat use. The strength of these interactions varies with resource availability, habitat complexity, and the complexity of predator communities. Restoring apex predators can be a valuable tool for biodiversity conservation, but it requires a comprehensive understanding of the ecosystem and potential negative consequences. The article also highlights the importance of considering bottom-up processes, such as habitat complexity and productivity, in understanding the dynamics of predator interactions. Case studies from New Zealand illustrate how complex interactions among invasive predators can further complicate management efforts. Overall, the authors emphasize the need for a holistic approach to managing predator communities to avoid unforeseen negative effects on biodiversity.The article by Euan Ritchie and C Johnson reviews the roles of predators, particularly apex predators, in regulating ecosystems and biodiversity. Apex predators, which are typically large and specialized hunters, play a crucial role in controlling smaller 'mesopredators' through intraguild interactions. The removal of apex predators can lead to mesopredator outbreaks, resulting in increased predation on smaller prey species. The suppression of mesopredators by apex predators is widespread and can have significant impacts on biodiversity. Apex predators control mesopredators through direct lethal encounters and fear-induced changes in behavior and habitat use. The strength of these interactions varies with resource availability, habitat complexity, and the complexity of predator communities. Restoring apex predators can be a valuable tool for biodiversity conservation, but it requires a comprehensive understanding of the ecosystem and potential negative consequences. The article also highlights the importance of considering bottom-up processes, such as habitat complexity and productivity, in understanding the dynamics of predator interactions. Case studies from New Zealand illustrate how complex interactions among invasive predators can further complicate management efforts. Overall, the authors emphasize the need for a holistic approach to managing predator communities to avoid unforeseen negative effects on biodiversity.