VARIATION IN ORGANISMS

This refers to differences among organisms of the same species due to the differences in the genes

they inherit and the environment they survive

in.

EXAMPLE:Variation of apples

VARIATION IN ORGANISMS

GENETIC VARIATION

ENVIRONMENTAL VARIATION

Environmental variations• This refers to differences amongst

organisms of the same species due to the different factors of the environment they are exposed to. Eg , exposure of organism to different temperatures, light, humidity, nutrients etc

• Such variations, because they are not genetically acquired but environmentary acquired or influenced characters, can not be inherited from parents to their offsprings.

GENETIC VARIATIONS

Continuous

variation

Discontinuous

variation

Genetic variations

• This refers to differences amongst organisms of the same species due to the differences in the genes they inherit from their parents. Eg some individuals are tall and others are short. This is because they inherited different genes from their parents.

•  Such variations can be inherited because they are genetically determined.

CONTINUOUS VARIATION

This is the type of variation of a given character/trait where by differences among

organisms of the same species are slight and grade into each other.

These characters can be measured and mean, mode and median can be obtained. eg Height, weight, intelligence,

waist line, length and width of structures, skin colour, yield of milk, fertility, number of grains on a maize cob.

Continuous variation is variation that has no limit on the value that can occur within a

population. A line graph is used to represent continuous variation and may be affected by

environment or genetic or both.

Some examples of continuous variation are :heightweight

heart ratefinger lengthleaf length

SUNBATHING CAN CAUSE TANNING OF SKIN

DIFFERENT PEOPLE HAVE DIFFERENT HEIGHTS

DISCONTINUOUS VARIATION

This the type of variation which shows clear-cut and sharp differences amongst organisms over a given trait.

Features persist through out the life time of an organism. They show distinct differences.

Eg finger print, tongue rollers and non tongue roller, colour blindness, blood group,

skin pigmentation (normal skin colour/albinism) eye colour etc.

Discontinuous variation is variation that has distinct groups for organisms to belong to. A bar graph is used to represent discontinuous variation and is affected by

genetic only.

Some examples of discontinuous variation are:tongue rollingfinger printseye colour

blood groups

NO MATTER WHAT YOU EAT, IT CANNOT CHANGE YOUR BLOOD

GROUP

DIFFERENT PEOPLE HAVE DIFFERENT HAIR

LINES.

CONTINUOUS VARIATIONS DISCONTINUOUS VARIATIONS

They refer to small, indistinct differences from the normal condition.

They refer to large, conspicuous differences from the parents.

They are already present in population. They are new variations through similar variations might have occurred previously.

They are also known as fluctuations.They are also known as mutations or spurts.

They are usually unstable and non-inheritable. They are usually stable and heritable.

They are due to chance segregation of genes during gamete formation, crossing over or chance combination during fertilization.

They are produced by change in genes or genome.

They can be represented by smooth curve. A curve is not produced.

They are very common in all organisms. They appear suddenly and in few cases only.