In natural communities, populations of different species vary greatly. The
interactions of these populations affect the size of the populations.
The seaweed forest is home to a large number of interacting populations.
Limiting Factors
Amount of food
Amount of living space
Amount of water
When a population becomes too large for the amount of a given resource, it will become a limiting factor.
Carrying Capacity
The largest a population can get in a given environment over a long period of time.
When a population get larger than the carrying capacity, a limiting factor causes the population to decline.
Competition
When two or more individuals or populations try and use the same limited resource.
Food
Water
Shelter
sunlight
Weird Science
Green herons make interesting use of biotic and abiotic part of their environment in Japan. They will drop sticks and even break crumbs
into the water to attract fish. Sometimes they catch a fish 2-3 seconds after they drop the bait!Pretty Cool!
Misconception Alert While it’s true that all members of an ecosystem have important
roles, some members are more important than others to the overall health of the ecosystem. Such species are called keystone species. Like removing the keystone that holds up the other stones in an arch, removing the keystone species can cause the whole system to collapse. This occurred when the sea otter was hunted to near extinction in the kelp forests of the Pacific Ocean. With the otters gone, nothing was left to eat the sea urchins, which multiplied and ate all the kelp. The kelp was home to dozens of animals, all of which disappeared, along with most of the sea urchins. When the sea otter
was reintroduced, all these organisms returned!
Discussion
The lynx relies primarily upon the snowshoe hare for food.
How would the abundance of plants affect the hare population?
What will happen to the lynx?
What happens when the food
runs out for the hare?
Prey
Prey need adaptations to escape the predator
Run/hide (burrow)
Live in groups
Camouflage
Poison/color warning
Symbiosis
Close long-term association between two or more species.
Individuals within a symbiotic relationship may: benefit be unaffected be harmed
Mutualism
Both organisms benefit
Bacteria in our intestine.
They get food
We get vitamins
Coral and algae
Coral provides home to algae
Algae provides food for the coral.
Parasitism
One organism benefits = parasite
Other organism is harmed = host
Can cause death of the host!
Coevolution
A long-term change that takes place in two species because of their close relationship with one another.
MimicryWhen one organism “mimics” another to take advantage of their defense’s.
Viceroy Butterfly
The viceroy and monarch were once thought to exhibit Batesian mimicry, where a harmless species mimics a toxic species. Studies conducted in the early 1990's suggest that the viceroy and the monarch are actually examples of Mullerian mimicry where two equally toxic species mimic each other to the benefit of each. Just goes to show you there's always something new to discover in the natural world!
Monarch Butterfly
The killdeer is a ground-nesting bird that will distract a predator from its nest or chick with a “broken-wing” display. It will limp and drag a wing on the ground making itself appear to be an easy catch. But because it is actually quite healthy, it always stays one step ahead of the predator.
Misconception Alert
The phrase balance of nature does not imply that the components of an environment are static. Populations are in balance when their sizes are stable. That stability is the result of constant interactions between individuals of a population, between populations in a community, and between populations and environmental factors.
Brain Food
Studies have shown that ducks can have one-half of their brain asleep while the other half is awake. The side that is awake can even have an eye opened and respond to stimuli. The sides can also switch so that the half that was awake can rest and the rested half can become alert. Why might this be helpful to ducks?
Honeyguides live in Africa and India and are so called because they lead honey badgers and humans to the nests of wild bees using a series of calls. After the nest has been raided for honey, the bird gets the chance to feed on bee grubs from the open nest.
The bird’s unique digestive system allows it to eat wax as well. Which animals in this story are in a mutualistic relationship?
Which animals are prey? Which are predators?