Apex predators are important because they operate
as a negative feedback on the prey populations,
providing ecological stability. Their population
is largely controlled by abundance of food, and
apex predators unable to find enough food will
die. In general, apex predators exist at low
populations and are therefore vulnerable to
hunting, both of the predators themselves and of
overhunting their prey. There are additional more
complicated dynamics too, including a fairly
recent "Mesopredator Release Hypothesis." This is
the idea that if you remove the apex predators
from the food chain, predators just below apex
(mesopredators) will quickly expand their
populations, leading to overhunting and possible
extinction of their prey. Essentially, apex
predators promote stability in ecosystems by
keeping their prey populations balanced correctly.
Scientists often model these effects on
populations with predator-prey dynamics
mathematical models, such as the Lotka-Volterra
(wolf and rabbit) model.
is a good summary of it, and while it can be
advanced, it gives some insight about how these
As with almost everything in ecology, this is
Apex predators are the animals (usually animals,
but sometimes fungi) that are at the "top" of the
food web, i.e. they eat other things, and nothing
eats them. Depending on the structure of the
ecosystem and the factors forcing it, they may or
may not control the populations of every other
species in the food web, all of the way down to
the plants and algae at the bottom.
Generally, which happens depends on the biology
and climate driving the ecosystem from the bottom.
If factors such as water, light, inorganic
nutrients, or disturbances (e.g. fire, storms) are
common and/or unpredictable, then the ecosystem
will be structured from the bottom-up, with the
plants/algae determining populations of everything
else. However, in a more stable environment, often
the apex predators will reduce the populations of
what they eat, which will in turn increase the
populations of the species on the next level down,
and so on.
Because of the second law of thermodynamics,
energy is lost through each level of the food web.
This means that there is very little energy left
over for the apex predators, which has the
consequence that the apex predators often have
smaller populations, and are more likely to be
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