survival of the fittest Flashcards
What is Darwin’s contribution to the theory of evolution?
Darwin believed that advantageous features for survival were passes from parents to offspring. Individuals without these features died and did not contribute to the next generation
What is the difference between Darwin and Lamarck’s theories of evolution?
Lamarck believed advantageous features were required through ones lifetime, organisms would grow or change their features to suit their environment. However Darwin believed organisms inherited features that they could not change. If these features were favoured the organsim would survive and contribute to the next generation.
What is evolution?
The gradual change of a species over a long period of time.
Explain the process of natural selection?
1.Variation of traits
2.Selection pressure that acts on a species
3. Individuals with favoured traits will survive, reproduce and pass on that trait to the next generation, those without the trait will die.
4. Over the next few generations the favoured trait will increase in the species.
Why is variation important?
It is needed for natural selection.
Identify selection pressures.
Climate, food sources, disease, predators
Why is natural selection often called ‘survival of the fittest’
Because natural selection is when those with the favoured or ‘fittest’ traits survive.
Use example of peppered moths to explain natural selection
Black peppered moth’s had the favoured trait ver white ones as they could camouflage in the air pollution and hide from predators.
What is a species?
A group of organism’s that can produce fertile offspring.
How do new species evolve according to natural selection?
They evolve gradually by natural selection which selects certain features as being advantageous. Mutations also create new traits/features.
What is spectiation?
The formation of a new species
How do species become isolated?
Behavioural, geographical, ecological and temporal isolation.
How can biologists identify if two groups of organisms are the same species?
If they can mate and produce fertile offspring.
What is a hybrid?
Infertile offspring of genetically simular species. e.g. a mule - a cross of a female hoarse and a male donkey
Define extinction
The complete disappearance of a species.
How does convergent evolution occur and what evidence is there to support it?
When two species living in a similar environment share similar features and look alike (even though they are not related by a common ancestor). The evidence is the precence of analogous features
How does divergent evolution occur and what evidence is there to support it?
When two species evolve from a common ancestor, they share homologous structure (similar structure but. may have different function)
What are homologous structures and what do they indicate about two species?
They have the same structure in different species but may have different functions - indicates a common ancestor. E.g. Pentadactyl limb (arm with 5 fingers)
What are analogous structures and what do they indicate about two species?
Features that have the same function in different species - indicates no common ancestor e.g Bat & Bird wings
What is a vestigial organ?
Organs that were once used
