<P> An apex predator, also known as an alpha predator or top predator, is a predator at the top of a food chain, upon which no other animals prey . Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic levels and serve as keystone species, vital to their ecosystems . One study of marine food webs defined apex predators as those feeding at trophic levels above four . Food chains are often far shorter on land, usually limited to the third trophic level--for example, wolves prey mostly upon large herbivores . The apex predator concept is applied in wildlife management, conservation and ecotourism . </P> <P> Apex predators affect prey species' population dynamics . Where two competing species are in an ecologically unstable relationship, apex predators tend to create stability if they prey upon both . Inter-predator relationships are also affected by apex status . Non-native fish, for example, have sometimes devastated formerly dominant predators . One lake manipulation study found that when the non-native smallmouth bass was removed, lake trout, the suppressed native apex predator, diversified its prey selection and increased its trophic level . </P>

What predator is at the top of the food chain