𝗕𝗜𝗢𝗟𝗢𝗚𝗬 (𝗢𝗩𝗘𝗥𝗖𝗥𝗢𝗪𝗗𝗜𝗡𝗚)

Master Segun's class. 

Welcome to Class!!e

I am eager to have you join me in this weekend class!!

In today's Biology class, We will be learning about

Overcrowding and Food Shortage. We hope you enjoy the class!

CONTENT

Overcrowding

Factors Causing Overcrowding

Effects of Overcrowding

Adaptation to Overcrowding

Food Shortage

𝗢𝗩𝗘𝗥𝗖𝗥𝗢𝗪𝗗𝗜𝗡𝗚

This is a situation in which a population increases beyond a point called the carrying capacity where the resources (eg food and space) are not enough to support all the individuals in the population. Therefore, overcrowding reduces the food and space available for individual species in the population.

FACTORS CAUSING OVERCROWDING

1. Natality: An increase in the rate at which a particular species gives birth in a restricted area result in overcrowding.

2. Increase in the food supply

3. A decrease in mortality: Overcrowding results when the rate of death of organisms in a habitat is lower than the rate of birth.

4. Immigration: Inflow of individuals into a habitat increases the population which later causes overcrowding.

5. Lack of dispersal of fruits or seeds of plants.

6. Social habits of animals like termites, ants and bees lead to their multiplication in the colony.

7. Inadequate space

EFFECTS OF OVERCROWDING

These include:

1. Shortage of food since the available food in the habitat in the habitat is rapidly eaten up due to overcrowding.

2. Shortage of space due to an increasing population of species.

3. Competition occurs as the organisms struggle for scarce resources eg food, space. The stronger ones get the resources while the weaker ones are deprived ie survival of the fittest.

4. Anti-social behaviors like fighting or cannibalism can result from the stress of overcrowding.

5. Easy spread of diseases such as tuberculosis in human (air-borne).

6. Preying or feeding on each other when food is in short supply.

7. Death of organisms as weaker organisms in overcrowding area easily dies off due to lack of food and space.

ADAPTATION TO AVOID OVERCROWDING

In order to survive overcrowding, plants and animals have developed the following adaptive features:

TERRITORIAL BEHAVIOUR

Animals like mammals, lizards, birds etc. establish territories which they are possessive of. They fight for and defend the territories against any intruders. A successful claim of the territory ensures sufficient food, space mating partners and parental care for the organisms.

SWARMING

This is exhibited by some social animals such as termite and bees when some of them move out from an old colony to a new one. Hence, overcrowding is avoided.

EMIGRATION

This is the outward movement of animals out of their locality to another place of settlement. This prevents overcrowding.

DISPERSAL OF SEEDS AND FRUITS

This could be by water, wind, animals, insects and explosive mechanism. The seeds and fruits are carried far away from the parent plants. Hence, overcrowding is prevented.

FORMATION OF CANOPIES

This is an attribute of forest trees. This helps the plants to trap enough sunlight and also prevent the shorter plants below from getting the light. The lower plants eventually, die off and overcrowding is avoided.

PRODUCTION OF CHEMICALS

Roots of some plants produce chemicals which prevent the growth of other plants close to them. Therefore, overcrowding is avoided.

FOOD SHORTAGE

In a well-established habitat, population sizes of various species are adjusted to the quantity of food that is available in the habitat. Factors that can decrease the food supply to the habitat thereby causing food shortage are as follows;

A natural disaster like flood, drought

Diseases of plants and animals

Pests such as locust, grasshoppers, weevils

Lack of or inadequate storage facilities

Bush burning which destroys soil organisms reduces soil fertility and exposes the soil to erosion.

All these results in poor yield and eventual food shortage

EFFECT OF FOOD SHORTAGE ON POPULATION SIZE

1. Competition: – Scarcity of food leads to struggling among organisms for any available food. This results in the survival of the fittest. This can result in fighting and cannibalism (animals feeding on themselves eg man)

2. Emigration: – Animals also move from an area of ​​food shortage to where sufficient food is available.

3. A decrease in the rate of reproduction: – Many human beings and marriage due to lack of or inadequate food supply may engage in family planning to reduce the number of children to be catered for.

GENERAL EVALUATION

1. What is a food shortage?

2. Outline four factors that cause a food shortage.

3. State three causes of food shortage.

4. State two outcomes of succession.

5. Discuss five adaptive features of organisms used to survive overcrowding.

READING ASSIGNMENT

College Biology, chapter 23, pages 541-544

WEEKEND ASSIGNMENT

SECTION A

1. The following except one results from food shortage A. Competition B. Reduced mortality rate C. Emigration D. Increased mortality rate.

2. Food shortage makes the population size A. increase B. decrease C. stabilize D. fluctuate

3. Food storage results in A. stability of price B. Natural disaster C. high natality rate D. overpopulation

4. These are methods of storing and preserving food except A. Silos B. barns C. refrigeration D. Marketing.

5. These are forms of adaptation to avoid overcrowding except A. Pairing B. Territoriality C. Swarming D. Canopy

SECTION B

1. (a) What is overcrowding?

(b) State five effects of overcrowding.

2. State five ways of improving crop yield.