natural selection

taxonomy

science of classifying animals based on their level of similarity

species

smallest unit of biological classification

• group of similar individuals that can breed to produce viable, fertile offspring

variation

• difference in traits between individuals of the same species

how does variation arise?

• homologous chromosomes crossing over in meiosis

• mutation

• random meeting of egg and sperm

trait

• any feature of an organism

acquired trait

• trait gained during lifetime

example of traits

• loss of limb

• tattoo

they are not passed to the next generation

genetic trait

• determined by DNA

  • passed down by genes

examples of genetic traits

• eye colour, dimples, height

natural selection

environmental factors that act upon a population

biotic

• living factor

examples of biotic factors

• predators

• competition

• bacterial infection

abiotic

• non living / physical factor

examples of abiotic factors

• physical geography

• water availability

• amount of light

VSRIG

1. variability

2. selection

3. reproduction

4. inheritance

5. generations

variability

• genetic variations are already pre-existing within a population

selection

• … of certain phenotypes for survival advantage over other phenotypes

  • e.g. black moths camouflage

reproduction

• by organisms who were selected

inheritance

• of advantageous phenotypes by offspring

generations

• frequency of phenotype increases

artificial selection

• choose to breed particular organisms with desirable features

cross breeding

• cross on individual with a desirable feature with another individual with a desirable feature