In the original Greek “oikos” means,”house”. So ecology is “the study of the house” theplace where you live, or the environment whichtechnically includes all those factors, both nonlivingand living, that affect an organism. Ecology then isthe study of the interactions of organisms in theirenvironment includes both the living (biotic) andphysical (abiotic) factors of the environment. It’salso the science, which formulates and testshypotheses about environment. Ecology is therelationships, identification and analysis ofproblems common to all areas. Ecology studiesthe population and the community, evaluates causeand effects of the responses of populations andcommunities to environmental change.
POPULATIONS The population is defined as anassemblage of individuals of a single species thatlive in the same place at the same time. Also,biologists add an additional condition: theindividuals in a population must interact with eachother to the point of being able to interbreed.
Population is important to understanding manyimportant ecological and evolutionary phenomena.
Ecologists can use information from populationecology to predict the success of a given speciesor assemblage of species. One attribute ofpopulations that is observed in nature is theirdispersion, or the way in which individuals aredistributed in a given area. Typically, biologistsrefer to three types of dispersion: – Clustered(aggregated), Regular (evenly spaced), Random(irregularly spaced) Populations showing aclustered pattern are common in nature and arefound among many different types of organisms.
Clustered dispersion patterns are often due toenvironment heterogeneity. Regular dispersionpatterns are relatively rare in nature and occurwhen a resource is scarce. A good example ofregular spacing occurs in animals that exhibitterritoriality, a phenomenon in which animalsestablish an area for themselves and fight off allother individual seeking to invade that area.
Regular dispersion patterns can also be observedin plants. Random patterns can be found in avariety of organisms (trout in lake or maple trees ina forest). Regardless of which organisms, thenumber of births almost always has the potential tobe greater than the number of deaths. In otherwords populations of all species have the capacityto grow. That property is crucial importance to thesuccess of all species. However, all species willnot increase under all circumstance, but insteadthey can, given appropriate conditions. There aretwo models of population growth: the exponentialmodel and the logistic model. One of the mostbasic models of population biology is theexponential growth equation, which is: )N/)t =rmaxN This equation states that, in a growingpopulation, the rate of change in population size isdetermined by the maximal intrinsic rate ofincrease (rmax) multiplied by the number ofindividuals in that population (N). If a populationgrowth very quickly we called that an exponentialincrease and its growth curve has a J-chapedcalled J-chaped curve. A population cannotcontinue to grow indefinitely because this equationcontains additional term called the carryingcapacity (K) which is not fixed, but carryingcapacity is constantly affected by many factors,both biotic (living) and abiotic (non-living). Thelogistic population growth predicts thatpopulations will grow rapidly at first. However, asthe number of individuals in the population (N)approaches the carrying capacity (K), thepopulation growth rate eventually slows to zero,and the population stabilize at K. The result is asigmoidal or S-shaped curve which is oftendivided into three phases: the first is called the lagphase (the period of slow growth that occurswhen population numbers are low). The second isthe log phase, which occurs when growth rateaccelerates and becomes relatively rapid. Thethird is the saturation phase, during whichpopulation growth decelerates as N approachesK. All species have a well-defined life history thatinvolves a beginning of life, a juvenile andreproductive phase and death. There are twoimportant parameters of a population: survivorship(how long one live) and fecundity (how manyoffspring one leaves). Survivorship is the numberstill living at the beginning of each age interval. Thenumber of deaths determines the death rate duringa given period of time divided by the number stillliving at the beginning of the time period.
COMMUNITIES A community is an assemblageof populations that interact with one another andthe effects that they have on each other oftengreatly influence their ability to survive andreproduce. Because they are assemblages ofdifferent species, communities have properties thatmake them unique from individual organisms andpopulations. Some communities simply blendgradually into others and for this reason are calledopen comments, forest communities are like that,as different vegetable types blend together.
Conversely, closed communities have moredefinite borders; few organisms pass from onecommunity to another. In these types ofcommunities, fewer organisms move in and out, sothey are more isolated in terms of energy andnutrients. Despite the fact that communities cansometimes be difficult to define, ecologists havebeen able to identify a lot of attributes by whichcommunities can be described and analyzed.
These include – Species composition which is themost fundamental attribute of a community. It’ssimply a list of species of which the community iscomprised. Communities vary tremendously intheir composition. – Frequency is a measure ofhow often we find a species in a community. -Distribution, or how species are arranged in acommunity – Diversity is a measure of the variationin a community, has two components. The first isrichness, which is the number of species in thecommunity. The second component is calledevenness, which is the degree to which thedifferent species are represented in a community. -Stability is the concept of the ability of acommunity to handle disturbance or to resist beingdisturbed. It also can refer to resilience of acommunity (that is, its ability to recover quicklyfrom a disturbance. Certain communities can becalled “fragile’ which is used to refer tocommunities that have low stability when facedwith human disturbance. Competition involves astruggle for limited resource. Exploitativecompetition is the use of the same resources inwhich one competitor has greater access than theother to the resources is. Interference competitionis actual fighting over resources. Intraspecificcompetition is between members of the samespecies and interspecific competition is betweendifferent species. The competition exclusionprinciple is that no two species can occupy thesame niche at the same time. Because the niche ofan organism (the way in which it interacts with itsenvironment) is often dependent on how it fares incompetition with its neighbors, both kind ofcompetition is important in the structure of thecommunity. BIOMES Biome is defined as large,distinct and recognizable associations of life. Moreprecisely, a biome is a particular array of plantsand animals within a geographic area broughtabout by distinctive climatic conditions. Their plantassociations than those of animals, not only usuallyidentify biomes more because the first is far moreobvious, but also because it determines thesecond. Ecologists recognize about a dozen majorbiomes, each one forms under a certain prevailingclimate and has a characteristic type of plant andanimal life. Some examples of biomes includegrassland, deserts, and deciduous forests. Biomesmay be subdivided into communities.
CONCLUSION For this paper, I read a lot ofbooks and did a lot of research on Internet. Ilearned a lot about ecology, population,communities and biomes. It’s very hard to writeabout this subject in only five pages. My first draftwas constituted of eight pages so I cut a lot ofdetails. However, I pass a lot of time to do thispaper and energy and I really enjoyed it. I hope itwill be the same for you Science