BRAINCAKENatural Selection
Revision notes for Natural Selection in Edexcel Biology (8BI0). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- The Theory of EvolutionEvolution is the gradual change in the inherited characteristics of a population over many generations.
- Neo-DarwinismNeo-Darwinism (the modern synthesis) combines Darwin's theory of natural selection with Mendelian genetics.
- AdaptationAn adaptation is a feature of an organism that increases its chance of survival and reproduction in its environment.
- Anatomical AdaptationAnatomical adaptations are structural features of an organism's body, inside or outside.
- Physiological AdaptationPhysiological adaptations are processes inside an organism's body, such as its biochemistry, metabolism and the way its organs work.
- Behavioural AdaptationBehavioural adaptations are the ways an organism acts that increase its chance of survival and reproduction.
- Grayling ButterfliesThe grayling (Hipparchia semele) is a butterfly of heathland, sand dunes and coastal cliffs in Britain.
- Fungal CarnivoresSome fungi are carnivores: they trap and digest tiny soil worms called nematodes.
- The Same Species in Different EnvironmentsMembers of the same species can look very different when they live in different environments.
- Natural SelectionNatural selection is the process by which individuals with characteristics that suit their environment are more likely to survive, reproduce and…
- Natural Selection in OystersOysters provide a clear, recent example of natural selection caused by disease, acting as a selection pressure.
- Natural Selection in MothsThe peppered moth (Biston betularia) is the classic example of natural selection observed in a real population.
- Reproductive SuccessNatural selection does not simply reward survival.
- Directional SelectionFor many characteristics, such as body mass or height, a population shows a range of values that forms a roughly normal distribution around a mean.
- AntibioticsAntibiotics are chemicals that kill bacteria or slow their growth without harming the cells of the person taking them.
- Antibiotic ResistanceAntibiotic resistance is the ability of bacteria to survive a dose of an antibiotic that would normally kill them or stop their growth.
- Preventing Antibiotic ResistanceEvery time an antibiotic is used, it selects for resistant bacteria.
- SpeciationSpeciation is the formation of a new species from an existing one.
- Types of IsolationSpeciation needs reproductive isolation: something must stop two groups exchanging alleles.
- Allopatric SpeciationAllopatric speciation is speciation that happens when populations are separated by a geographical barrier. 'Allopatric' means 'different homeland'.
- Endemic SpeciesAn endemic species is a species that is found naturally in only one geographical area and nowhere else in the world.
- Desert PupfishDesert pupfish are small fish of the genus Cyprinodon that live in isolated springs, streams and pools in the deserts of south-western USA and…
- Adaptive RadiationAdaptive radiation is the rapid evolution of many new species from a single common ancestor, with each new species adapted to a different niche.
- Sympatric SpeciationSympatric speciation is the formation of a new species from a population in the same geographical area, without any physical barrier. 'Sympatric'…
- Howea Palm TreeThe Howea palms of Lord Howe Island are one of the best-supported examples of sympatric speciation.
- Fruit Fly Rhagoletis pomonellaThe apple maggot fly (Rhagoletis pomonella) of North America is an example of sympatric speciation that may be happening now.
- Cichlid FishCichlids are a family of freshwater fish found mainly in Africa and Central and South America.
- Cichlid SpeciationThe many cichlid species in each African lake evolved in the same body of water, so much of their speciation is thought to be sympatric.
- Cichlids Under ThreatThe huge diversity of cichlids in Lake Victoria has declined sharply since the mid-twentieth century.