B15 - Evolution Flashcards
Mendel?
Theory?
Year?
Gregor Mendel was Austrian monk. He carried out breeding experiments on peas, and found that characteristics were inheritable in clear and predictable patterns.
‘Units’ we’re passed on and determined the characteristics.
Mid 19th century.
D. Biodiversity?
A measure of the variety of all the different species of organisms on earth.
D. Natural selection?
The process by which evolution takes place. Organisms produce more offspring than the environment can support. Only those most suited to their environment will survive to breed and pass on their useful characteristics.
D. Selective breeding?
Speeds up natural selection by selecting animals or plants for breeding that have a required characteristics.
D. Species?
The smallest group of clearly identifies organisms in Linnaeus classification system, often described as a group of organisms that can breed together and produce fertile offspring.
D. Speciation?
The process of developing different species;
• Isolation
• Genetic variation between populations
• Natural selection operates differently on the two populations
• Speciation - when populations become so different that successful interbreeding is no longer possible.
Discovery in the early 20th century? (Linked to Mendel’s ‘units’)
Chromosomes and ‘units’ behaved similarly. Led to idea that ‘unit’ (genes) were located in chromosomes.
Lamarck?
Theory?
Argument against?
French biologist.
The ‘fountain of life’, idea that all animals evolved from primitive worms, the change from worm to organism was caused by the inheritance of acquired features. ‘Use it or loose it’ - of animals used a feature a lot it would grow and be passed into offspring.
No evidence, changes in people’s bodies didn’t get passed onto offspring.
Darwin?
Theory?
Year?
Theory of evolution by natural selection. Survival of the fittest, animals most suited to their environment would survive and pass on features that enabled them to survive onto offspring.
Why was Darwin’s theory only accepted gradually?
- conflict with the church and belief God made every animal.
- insufficient evidence.
- no way of explaining variation and inheritance.
Alfred Russel Wallace?
Theory?
Independently proposed the theory of evolution by natural selection. Published joint writings with Darwin in 1858 which prompted Darwin to publish his findings before Wallace did.
Theory of specification.
D. Speciation?
The process of the formation of a new species
Stages of speciation? (6)
- Isolated populations
- Genetic variation of different populations (mutations occur)
- Alleles helping animal survive in new conditions selected = adaptations
- Individuals with useful adaptations survive
- Animals interbreed and pass on useful alleles to offspring
- Genetic variation between populations increases over time
- Eventually 2 populations become so different that they cant interbreed to produce fertile offspring
D. Natural selection?
The process by which evolution takes place
Explain Natural Selection?
In different populations, alleles that control characteristics which will help animals survive will be selected. this helps the organism to live and breed successfully.
(Part of Speciation)
