How does predation and herbivory shape communities

As predator populations increase, they put greater strain on the prey populations and act as a top-down control, pushing them toward a state of decline. Thus both availability of resources and predation pressure affect the size of prey populations. Ruslanas Gauselmann Pundit. How does biodiversity affect the stability of an ecosystem?

Increased alpha diversity the number of species present generally leads to greater stability , meaning an ecosystem that has a greater number of species is more likely to withstand a disturbance than an ecosystem of the same size with a lower number of species. Andoitz Otrohov Pundit. Of course predators consume prey , but in doing so, they may have broader impacts on communities as a whole.

That is to say, predators help to maintain a balance among organisms, both by consuming prey and by altering prey behavior and prey habitat selection. Mamoun Diepa Pundit. How do predators affect the ecosystem? There's consistent evidence that large predators help keep populations of large herbivores in check, with positive effects on ecosystem health. Jilali Uhlenbusch Pundit. How do predators regulate prey populations? Prey control predator populations intrinsically because predators depend entirely on prey populations to survive.

But of course, predators also control prey populations and do so directly by reducing the size of those populations by the number of prey individuals they consume. Dario Terks Teacher. What would happen if a predator took over an environment? The most obvious result of the removal of the top predators in an ecosystem is a population explosion in the prey species. More predators kill more prey, which, along with food scarcity, decreases the population. When prey becomes more scarce, the predator population declines until prey is again more abundant.

Sainey Bombillar Teacher. Do Predators have strong impacts on ecosystems? The strengths of top predator effects on community properties were modest compared with nonterrestrial systems.

But, predator -caused changes in plant community structure via alteration of plant dominance, and hence plant species evenness, strengthened effects on ecosystem properties. Policarpio Folha Teacher. Are humans apex predators? Humans are not considered apex predators because their diets are typically diverse, although human trophic levels increase with consumption of meat. Aidas Samon Teacher. What is the process of succession?

Ecological succession is the process of change in the species structure of an ecological community over time. It is a phenomenon or process by which an ecological community undergoes more or less orderly and predictable changes following a disturbance or the initial colonization of a new habitat. Sofia Kobke Reviewer.

What are the good effects of predation? First, predation acts to increase growth rate by thinning the density of prey populations, which releases survivors from competition. A community is bound together by the network of influences that species have on one another. Inherent in this view is the notion that whatever affects one species also affects many others -- the "balance of nature". We build an understanding of communities by examining the two-way, and then the multi-way, interactions involving pairs of species or many species.

Energy enters this biological web of life at the bottom of the diagram, through the photosynthetic fixation of carbon by green plants. Many food webs also gain energy inputs through the decomposition of organic matter, such as decomposing leaves on the forest floor, aided by microbes.

River food webs in forested headwater streams are good examples of this. Energy moves from lower to higher trophic feeding levels by consumption: herbivores consumes plants, predators consume herbivores, and may in turn be eaten by top predators.

Some species feed at more than one tropic level, hence are termed omnivores. Figure 1 provides a simplified model of such a food web. Generalized food web. A food web is an assemblage of organisms, including producers, consumers and decomposers, through which energy and materials may move in a community We can look at this food web in two ways. It can be a diagram of the flow of energy carbon from plants to herbivores to carnivores, and so on. We will take this approach when we examine energy flow in ecosystems.

In addition, members of a food web may interact with one another via any of the four interaction types named above. An interaction between two species in one part of the web can affect species some distance away, depending on the strength and sign of the inter-connections. Often, adding a species as when an exotic species invades a new area or removing a species as in a local extinction has surprisingly far-reaching effects on many other species.

This is due to the complex inter-connections of species in ecological webs. Ecologists use the following terms to describe various categories of the effects of a change in abundance, or presence vs absence of one species on another. Direct effects refer to the impact of the presence or change in abundance of species A on species B in a two-species interaction. Keystone species are those which produce strong indirect effects. The keystone species concept is one of the best-known ideas in community ecology.

Although it is true that many species potentially interact with one another in a food web such as depicted in Figure 1, in nature there are big players and little players. The biggest players of all are referred to as keystone species. This is a species whose presence or absence, or substantial increase or decrease in abundance, profoundly affects other species in the community.

Evidence usually comes from experiments in which one species is added to or removed from a community. The name derives from the center stone in an arch supporting its weight by inward-leaning stones. Predators that ignore this coloration and eat the organisms will experience their unpleasant taste or presence of toxic chemicals and learn not to eat them in the future.

This type of defensive mechanism is called aposematic coloration , or warning coloration. Figure 4. While some predators learn to avoid eating certain potential prey because of their coloration, other species have evolved mechanisms to mimic this coloration to avoid being eaten, even though they themselves may not be unpleasant to eat or contain toxic chemicals.

In Batesian mimicry , a harmless species imitates the warning coloration of a harmful one. Assuming they share the same predators, this coloration then protects the harmless ones, even though they do not have the same level of physical or chemical defenses against predation as the organism they mimic. Many insect species mimic the coloration of wasps or bees, which are stinging, venomous insects, thereby discouraging predation Figure 5.

Figure 5. Batesian mimicry occurs when a harmless species mimics the coloration of a harmful species, as is seen with the a bumblebee and b bee-like robber fly.

Figure 6. Several unpleasant-tasting Heliconius butterfly species share a similar color pattern with better-tasting varieties.

Figure 6 shows a variety of foul-tasting butterflies with similar coloration. This type of mimicry is extremely rare and more difficult to understand than the previous two types. For this type of mimicry to work, it is essential that eating the milk snake has unpleasant but not fatal consequences. Then, these predators learn not to eat snakes with this coloration, protecting the coral snake as well.

If the snake were fatal to the predator, there would be no opportunity for the predator to learn not to eat it, and the benefit for the less toxic species would disappear. Go to this website to view stunning examples of mimicry. Improve this page Learn More. Skip to main content.

Module Ecology of Living Things.