ECOLOGY OF POPULATION: INTRODUCTION, OVERCROWDING, FACTORS AFFECTING A POPULATION, BALANCE IN NATURE, FAMILY PLANNING

Population is the number of individuals of the same species interacting in a habitat at the same time. This individuals cohabit cohabit and compete virtually for everything ranging from food, water, dominance, territories, etc. When individuals compete, there are chances that the most viable ones will remain and the weaker ones will be dominated upon.

OVERCROWDING
Overcrowding is the result of an increase in the population beyond the carrying capacity of a particular area.

FACTORS THAT MAY CAUSE OVERCROWDING
A. Survival rate or increase in birth rate.
B. Immigration.
C. Social habit, e.g. increase in one colony by termites or bees.
D. Absence of dispersal.
E. Absence of predators.

EFFECTS OF OVERCROWDING
1. Restlessness.
2. Aggression or Fighting.
3. Death or Epidemic.
4. Competition.
5. Cannibalism and
6. Decrease in natality rate.

ADAPTATION TO OVERCROWDING
1. Territorial behaviour.
2. Emigration.
3. Fruits and Seeds Dispersal.
4. Swarming (leaving an old colony to establish a new one0.
5. Roots of many plants produce chemicals to prevent the growth of other plants close to them.

IMPORTANCE OF WATER, COMPETITION, AND PATHOGEN IN A POPULATION AND HOW THEY AFFECT ITS GROWTH

WATER
Water is needed by all organisms in a population for metabolism, growth in population, for survival. Lack of water leads to death of organisms in a population or migration, therefore, leading to reduction in the size of the population.
Excess water can also be dangerous to the organism or cause flooding or drowning or water-logging leading to reduction in population size.

COMPETITION
Limited space, food, and other nutrients leads to competition. Organisms in the population that are unable to compete successfully for food and other nutrients die while the more active ones survive, sometimes called survival of the fittest leading to reduction in the size of population or structural changes in population or migration or dispersal.
When there is no competition, the size of the population increases.

PATHOGENS
Pathogens are harmful disease-causing organism which kill other organisms in a population.
An attack by pathogens leads to a reduction in the size of a population, the development of resistant strains, disease free population multiplies and grows rapidly.

BALANCE IN NATURE
Excess or shortage of abiotic and biotic factors causing increase and decrease in the number of individuals in the population of any organism produces a limit in population. The net effect of these factors is that the population size of living organisms tends towards a dynamic equilibrium called Balance in Nature.

The abiotic and biotic factors that control population of organisms make up what is called Environmental Resistance. The environmental resistance opposes excessive increase in number of any population of organism. It appears that as the number of a population increases, the environmental resistance increases also, e.g. as the number increases, the amount of food available to each member of the population tends to decrease. This results in competition for the available food and organisms that cannot get the food dies. Through this kind of control, the population is kept relatively constant.

Human beings can control their population through family planning and birth control.

The biological equilibrium in nature is maintained by the predator prey relationship.

FAMILY PLANNING
The deliberate limitation or spacing of births is called Family Planning. This comes as a result based on the decision of the couples, the economic factors, the number of babies intending couples want to have, and their will power.

Decisions concerning family planning are usually made on an individual basis, but some governments have used financial incentives or penalties in an attempt to influence individual decisions.

Limitation of the number of children born, either to an individual or within a population is known as Birth Control. Most people in developed countries now practice birth control as a means of controlling their population, this having an effect of decreased population growth rates. Furthermore, in some countries, political and social pressures are applied to couples in an attempt to reduce population growth. Nevertheless, the total world population continues to increase rapidly. Strategies for family planning include different methods of contraception.

BIRTH CONTROL OR FAMILY PLANNING DEVICES
1. Condom
2. Sterilisation
3. Spermicides.
4. Intra-Uterine device.
5. Contraceptive pills or Injections.

METHOD OF CONTRACEPTION
There are different methods of contraception; the natural methods, barrier methods, hormonal methods, and postictal methods. Sterilization interferes with part of the male or female reproductive system to render the individual infertile.

THE CONDOM
This is a tube shaped piece of latex rubber that usually has a teat to hold ejaculate. It should be used with spermicide, examined for holes before use, and have all air squeezed out of the tip to prevent bursting. The rim should be held during withdrawal to stop the condom from slipping off.

STERILIZATION
This offers an almost completely safe and reliable form of birth control. It is usually irreversible, it has no effect on the production of sex hormones, so a man produces sperm-free semen and a woman produces normal eggs.

THE PILL
This prevents ovulation, changes the cervical mucus to prevent sperm penetration, or alters the uterine lining to prevent implantation.

MUCOSAL AND TEMPERATURE METHODS
The temperature method involves charting the woman’s temperature to ascertain whether ovulation has taken place. The mucosal method involves studying the cervical mucus throughout the woman’s menstrual cycle.

HORMONAL METHOD
This involves capsules containing a progesterone which is inserted into the arm where they release progesterone into the blood.

DIAPHRAGM IN POSITION
This is held in place over the cervix by means of a coiled metal spring in its rim, the diaphragm prevents sperm from reaching the cervix.

IUD IN POSITION
A small piece of moulds plastic with string attached sometimes with copper or female hormones added. The IUD is worn in the uterus.

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