• process in which individuals best suited in the environment survive and reproduce naturally to produce their phenotype offsprings.
• selection pressure is exerted by environmental factors eg presence of light and nutrients may affect the survival of plant organism in a given area.
• it results in competition for light and nutrients.
• the best adapted organism only survive to reproduce whilst other organisms die.

The role of natural selection in evolution.

• individuals in population have great reproductive potential;
• in population remain roughly constant ;
• many fail to survive / die ;
• do not reproduce ;
• due to environmental factors / named factor ;
• variation in members of population ;
• those best adapted survive ;
• reproduce / pass on alleles ; R genes
• genetic variation leads to change in phenotype ;
• ref: changes in gene pool ;
• over time produces evolutionary change ;
• new species arise from existing ones

Why variation is important in natural selection.

• ref. continuous / discontinuous variation ;
• genetic / inherited variation ;
• variation in phenotype / characteristics ;
• (can be due to) interaction of genotype and environment ;
• e.g. of characteristic that influences survival ;
• ref. intraspecific competition / struggle for existence ;
• those with favourable characteristics survive / AW ;
• pass on favourable characteristics to offspring ;
• those with disadvantageous characteristics die ;

How natural selection may bring about evolution.

• individuals in population have great reproductive potential ;
• numbers in population remain roughly constant ;
• variation in members of population ;
• environmental factors / named factor (biotic or abiotic) ;
• (cause) many, fail to survive / die / do not reproduce ;
• those best adapted survive / survival of the fittest ;
• (reproduce to) pass on alleles ; R genes
• genetic variation leads to change in phenotype ;
• ref: changes in, gene pool / allele frequency ;
• over time produces evolutionary change ;
• new species arise from existing ones / speciation ;
• directional / stabilizing, selection ;

Diffenceres between natural and artificial selection