natural and artificial selection

definition of variation

differences between organisms of the same species

importance of variation

to provide adaptations so that organisms can survive in ever changing environment

is continuous variation quantitative or qualitative?

quantitative

is discontinuous variation quantitative or qualitative?

qualitative

describe/define continuous variation

individuals in a population show a gradation from one extreme to the other

describe/define discontinuous variation

individuals in a population shows no gradation from one extreme to the other

what variation that’s affected by environmental factor

continuous variation

how continuous variation differ from discontinuous variation

continuous variation has intermediate characteristics within the same species

what caused discontinuous variation

genetic factors

does discontinuous variation affected by environmental factor

no

what variation is height and weight

continuous variation

what variation is blood group

discontinuous variation

what variation is the skin colour

continuous variation

what can caused genetic variation

-sexual reproduction

-crossing-over

-chromosome mutation

-hybridisation

-etc

what is meant by selection

a process whereby one or more factors acting on phenotypes favour the transmission of particular alleles tothe following generation

types of selection

natural and artificial

what is natural selection

a biological theory that explains why organisms seem match their environmental niches so well.

natural selection acts directly on genotype or phenotype

phenotype

what are the types of selections

-stabilising selection

-discuptive selection

-directional selection

-sexual selection

-polymorphism

stabilising selection

genetic diversity decreases as the population stabilises on a particular trait

disruptive selection

Favours individuals and both extremes of a characteristic range

directional selection

Favours individuals at one end of the spectrum

sexual selection

Selection with respect to mating success

polymorphism

Refers to many different phenotypes found in population

What is artificial selection

A process of intentional or unintentional notification of a species/human action that encourages the breeding of certain traits over others.

What is a gene bank?

A type of biorepository which preserves genetic materials.

What type of selection that has its extreme values of character are selected against?

Stabilising selection.

What type of selection that has the emergence two distinct phenotypes?

Disruptive selection.

What type of selection that favours a single allele and allele people to shift to one direction?

Directional selection.

What type of selection that has some individuals are more successful than others in attracting mates?

Sexual selection.

What type of selection that has human interference involved?

Artificial selection.

What are the types of polymorphism?

Balance polymorphism and transient polymorphism.

what type of selection is this?

disruptive selection

what type of selection is this?

directional selection

what type of selection is this?

stabilising selection

describe balanced polymorphism.

two or more alleles of a gene are maintained in am population because each is favoured by a separate environment force.

(two or more forms coexists in a stable ratio in a population)

describe transient polymorphism.

occurs when a morph is in the process of spreading through a population.

In an event of malaria infection do people with normal haemoglobin (HH) survive the disease?

no they die