D4.1 Natural Selection

Process of natural selection

→ survival of the fittest

1. overproduction of offspirng

2. genetic variation due to meiosis

3. best adapted will survive and pass on alleles to future generations

Sources of variation

• mutations

• meiosis

• sexual reproduction

Carrying capacity

maximum number of organisms that an environemnt can provide for

Why is natural selection importnat (compettion for resoucres)

• plants and animals produce mor eoffspirng that can surive

• leaidng to competition for habita reosruces etc

• called struggle of survival

→ thats why natural selection is importnat

Selection pressure

factor that can infleunce success of a population and hence allele frequencies

Abitoic denisty independent selection pressures

• temprature

• humidity

• availabitlty of light

• ph of water or soil

Example of selection pressure

Magellanic penguins

→ not adapated to rain

• with climate change more rain

• causes their feathers to stick to body

• reduces thermal insulation

• leading to hypotehrmia and death

Fitness

• high fitness - better adapted more liekly to survive

• low fitness - worse adapted less liekly to survive

reproductive potential

macimum number of offpsirng that can be produced with no infant moretality

heritable traits

→ encoded in DNA

can be passed on to offspirng

Aquired characteristics

• aquired during life due to environment

• does not change DNA

Example of aquired characteristic

Flamingos

→ not pink

→ eat plankon with beta karotene causing pink colour