Ecology

In the original Greek “oikos” means,
“house”. So ecology is “the study of the house” the
place where you live, or the environment which
technically includes all those factors, both nonliving
and living, that affect an organism. Ecology then is
the study of the interactions of organisms in their
environment includes both the living (biotic) and
physical (abiotic) factors of the environment. It’s
also the science, which formulates and tests
hypotheses about environment. Ecology is the
relationships, identification and analysis of
problems common to all areas. Ecology studies
the population and the community, evaluates cause
and effects of the responses of populations and
communities to environmental change.

POPULATIONS The population is defined as an
assemblage of individuals of a single species that
live in the same place at the same time. Also,
biologists add an additional condition: the
individuals in a population must interact with each
other to the point of being able to interbreed.

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Population is important to understanding many
important ecological and evolutionary phenomena.

Ecologists can use information from population
ecology to predict the success of a given species
or assemblage of species. One attribute of
populations that is observed in nature is their
dispersion, or the way in which individuals are
distributed in a given area. Typically, biologists
refer to three types of dispersion: – Clustered
(aggregated), Regular (evenly spaced), Random
(irregularly spaced) Populations showing a
clustered pattern are common in nature and are
found among many different types of organisms.

Clustered dispersion patterns are often due to
environment heterogeneity. Regular dispersion
patterns are relatively rare in nature and occur
when a resource is scarce. A good example of
regular spacing occurs in animals that exhibit
territoriality, a phenomenon in which animals
establish an area for themselves and fight off all
other individual seeking to invade that area.

Regular dispersion patterns can also be observed
in plants. Random patterns can be found in a
variety of organisms (trout in lake or maple trees in
a forest). Regardless of which organisms, the
number of births almost always has the potential to
be greater than the number of deaths. In other
words populations of all species have the capacity
to grow. That property is crucial importance to the
success of all species. However, all species will
not increase under all circumstance, but instead
they can, given appropriate conditions. There are
two models of population growth: the exponential
model and the logistic model. One of the most
basic models of population biology is the
exponential growth equation, which is: )N/)t =
rmaxN This equation states that, in a growing
population, the rate of change in population size is
determined by the maximal intrinsic rate of
increase (rmax) multiplied by the number of
individuals in that population (N). If a population
growth very quickly we called that an exponential
increase and its growth curve has a J-chaped
called J-chaped curve. A population cannot
continue to grow indefinitely because this equation
contains additional term called the carrying
capacity (K) which is not fixed, but carrying
capacity is constantly affected by many factors,
both biotic (living) and abiotic (non-living). The
logistic population growth predicts that
populations will grow rapidly at first. However, as
the number of individuals in the population (N)
approaches the carrying capacity (K), the
population growth rate eventually slows to zero,
and the population stabilize at K. The result is a
sigmoidal or S-shaped curve which is often
divided into three phases: the first is called the lag
phase (the period of slow growth that occurs
when population numbers are low). The second is
the log phase, which occurs when growth rate
accelerates and becomes relatively rapid. The
third is the saturation phase, during which
population growth decelerates as N approaches
K. All species have a well-defined life history that
involves a beginning of life, a juvenile and
reproductive phase and death. There are two
important parameters of a population: survivorship
(how long one live) and fecundity (how many
offspring one leaves). Survivorship is the number
still living at the beginning of each age interval. The
number of deaths determines the death rate during
a given period of time divided by the number still
living at the beginning of the time period.

COMMUNITIES A community is an assemblage
of populations that interact with one another and
the effects that they have on each other often
greatly influence their ability to survive and
reproduce. Because they are assemblages of
different species, communities have properties that
make them unique from individual organisms and
populations. Some communities simply blend
gradually into others and for this reason are called
open comments, forest communities are like that,
as different vegetable types blend together.

Conversely, closed communities have more
definite borders; few organisms pass from one
community to another. In these types of
communities, fewer organisms move in and out, so
they are more isolated in terms of energy and
nutrients. Despite the fact that communities can
sometimes be difficult to define, ecologists have
been able to identify a lot of attributes by which
communities can be described and analyzed.

These include – Species composition which is the
most fundamental attribute of a community. It’s
simply a list of species of which the community is
comprised. Communities vary tremendously in
their composition. – Frequency is a measure of
how often we find a species in a community. –
Distribution, or how species are arranged in a
community – Diversity is a measure of the variation
in a community, has two components. The first is
richness, which is the number of species in the
community. The second component is called
evenness, which is the degree to which the
different species are represented in a community. –
Stability is the concept of the ability of a
community to handle disturbance or to resist being
disturbed. It also can refer to resilience of a
community (that is, its ability to recover quickly
from a disturbance. Certain communities can be
called “fragile’ which is used to refer to
communities that have low stability when faced
with human disturbance. Competition involves a
struggle for limited resource. Exploitative
competition is the use of the same resources in
which one competitor has greater access than the
other to the resources is. Interference competition
is actual fighting over resources. Intraspecific
competition is between members of the same
species and interspecific competition is between
different species. The competition exclusion
principle is that no two species can occupy the
same niche at the same time. Because the niche of
an organism (the way in which it interacts with its
environment) is often dependent on how it fares in
competition with its neighbors, both kind of
competition is important in the structure of the
community. BIOMES Biome is defined as large,
distinct and recognizable associations of life. More
precisely, a biome is a particular array of plants
and animals within a geographic area brought
about by distinctive climatic conditions. Their plant
associations than those of animals, not only usually
identify biomes more because the first is far more
obvious, but also because it determines the
second. Ecologists recognize about a dozen major
biomes, each one forms under a certain prevailing
climate and has a characteristic type of plant and
animal life. Some examples of biomes include
grassland, deserts, and deciduous forests. Biomes
may be subdivided into communities.

CONCLUSION For this paper, I read a lot of
books and did a lot of research on Internet. I
learned a lot about ecology, population,
communities and biomes. It’s very hard to write
about this subject in only five pages. My first draft
was constituted of eight pages so I cut a lot of
details. However, I pass a lot of time to do this
paper and energy and I really enjoyed it. I hope it
will be the same for you
Science