TA competition..notebook
1 May 31, 2016
Mai 3109:17
Competition.
We are learning:
Competition occurs when organisms inhabit the same niche.
Intraspecific competition (Inbetween organisms of the same species) Interspecific competition (inbetween different species)
Mai 3016:21
Overview of a niche:
Remember, the niche is the physical AND biological environment of an organism.
Normally, when defining a niche we look at 3 sets of parameters:
1) Range of physical factors for survival and reproduction: temperature, humidity, pH, soil, sunlight, etc.
Gardeners of course are familiar with many of these parameters. When you buy plants or seeds you buy them with your garden in mind; some plants cannot live in wet soils, others require shade, still others need acid soils. Animals likewise have similar requirements; a tropical lizard like the iguana cannot survive the cold winter of a temperate forest.
2) Biological factors: predators, prey, parasites, competitors, etc.
An organism's niche may be further described by how it relates to other organisms. Squirrels require oak trees and their acorns for food, compete with chipmunks and deer and acorn weevils for the acorns, must avoid predators like hawks, and so on.
3) Behaviour: seasonality, diurnal patterns, movement, social organization, etc.
An organism's behaviour will further define its niche. Organisms might be nocturnal, or burrowers (or both). They may migrate like many songbirds; they may be part of a colony of social insects like bees or a herd like bison.
A niche is the place where an organism lives (its habitat) as well as all the aspects defined above.
Mai 3016:28
Competition: Whenever two niches overlap, competition ensues between organisms.
The reason is simple enough.
If two organisms have the same requirements for food, water, nesting sites, whatever there will not be enough of that thing to go around (technically speaking, the things the organisms are competing for are called resources ).
Mai 3110:10
Intraspecific competition occurs within the species.
The niche overlap here is near 100%. Individuals of the same species compete for the exact same things in the environment, therefore this is the strongest type of competition.
Mai 3016:48
Interspecific competition is waged between species. It can be fierce, if the competing species are similar, but it is never as strong as intraspecific competition. It is easy to see why. Take squirrels and chipmunks, for example. They compete for acorns and a few other resources, but they do not compete with each other for nesting sites (squirrels nest in trees, chipmunks underground), or for mates (one hopes). Therefore while a chipmunk might have to work very hard to get acorns before a rival squirrel does, he will compete more strongly with another chipmunk who will also be after his nest and any female chipmunks in the area.
Whatever the type of competition, it will be strongest at high population densities . The more organisms there are, the more strongly they will compete for the remaining resources.
Mai 3016:43
Paramecium in the same niche.
Competition shapes the natural world to a great extent. One principle of ecology is called competitive exclusion.
Two species competing for the same limiting resource in an area cannot coexist. This means that it is rare indeed to find two very closely related species in the same area. If they are closely related they will compete for almost all of the same things, and this will mean that inevitably they will compete for some item that is in short supply (the limiting resource). One species or the other will be better at the competition and will displace the other.
TA competition..notebook
2 May 31, 2016
Mai 3109:52
One trick that some organisms use to reduce competition within the species is to partition the habitat between the young and the adults. Many insects do this; caterpillars, for instance, feed on plants while butterflies only sip nectar. Likewise, tadpoles live in the water feeding on algae while the adult frogs are carnivorous, and, in many species, live away from the water.
Reducing competition between species.
Mai 3109:46
If two similar species are found in the same place, then after careful examination we often find that they differ in the way they use the resources is some critical, but often not apparent way.
For example, a series of birds might feed in the same trees for the same insects. However, each species might forage only on a particular part of the tree such as the top, the bottom, the inner branches, etc.
The Warblers for example, inhabit different sections of the same tree. In this way they see (and eat) an entirely different set of insects.
