_______ grow quickly and reproduce quickly without a natural predator.

keystone species
invasive species
apex predator
primary producer

The correct answer is invasive species. Invasive species are organisms, typically non-native to an ecosystem, that rapidly grow in number, outcompete the native species, and cause harm to the environment, economy, or human health. Because they do not have natural predators in their new environment, they often thrive and multiply quickly.