Adaptation & evolution Flashcards
Define community
The number of different species in the same environment
Define habitat
The place where an organism lives
Define population
The total number of organisms of the same species
Define environment
The factors affecting the habitat of an organism
Define niche
The role that an organism plays within its community
Define species
Organisms capable of interbreeding to produce fertile offspring
Define biodiversity
The variety of different species in a habitat
What does biotic and abiotic mean?
Biotic - living factors in an ecosystem
Abiotic - non living factors in an ecosystem
What are biotic factors that affect a habitat?
Soil
Oxygen level
Climate
Moisture level/water
Sunlight
Temperature
What are abiotic factors that affect a habitat?
Producers
Herbivores
Carnivores
Decomposers
Parasites
Producers
Define adaptation
Being suited to the environment that an organism lives in
What are the categories of adaptation?
- Behavioural
- Anatomical
- Physiological
What are features of behavioural adaptations?
Actions that have evolved to increase the chance of survival. They can be learnt or inherited.
What are examples of behavioural adaptations?
- The hunting behaviour of cheetahs
- A spider’s web
What are features of anatomical adaptations?
Physical structures that have evolved to increase the chance of survival
What are examples of anatomical adaptations?
- Giraffe’s long necks
- Walrus blubber
What are the features of physiological adaptations?
Processes within the body that have evolved to increase the chance of survival
What are examples of physiological adaptations?
- Snake venom
- Mammals shivering
What are extremeophiles?
Microorganisms that can survive in extreme conditions (pH, temperature etc.)
What is co-adaptation?
When 2 or more organisms become dependent on each other for survival and as a result become more physically possible
What are the key words for natural selection?
- Variation
- Mutation
- Selection pressure
- Selective advantage
- Survive
- Reproduce
- Inherit
- Allele
What is natural selection?
- Mutations can introduce new alleles into a population, so individuals within a population show variation in their phenotypes.
- Selection pressures such as competition create a struggle for survival.
- Individuals without the advantageous allele don’t survive. This means there are fewer individuals and less competition for resources.
- Individuals with the selective advantage are more likely to survive, reproduce and pass on their advantageous alleles to their offspring.
- Over time, the frequency of the advantageous allele increases.
Describe the peppered moth story.
- There was variation within species for wing colour.
- Due to some having a mutation and they were slightly darker.
- The colour of trees changed which became a selection pressure.
- The darker wings was a selective advantage as they could camouflage.
- This meant they could survive and not be eaten by birds.
- Those who survived could reproduce and pass on the advantageous alleles.
- The offspring inherited the allele.
What are the types of selection?
Directional
Stabilising
What is directional selection?
When having a phenotype on either side of the mean in the population allows reproductive advantage. Shifts in direction of selection pressure.
What is stabilising selection?
When having a phenotype at the mean/average is favourable, extremes of a phenotype are selected against
Explain allopatric speciation
- Normal mating can occur as organisms can move freely between populations.
- Species become separated somehow by geographical isolation ie river forms.
- Normal genetic variations in the populations.
- They face different environments and selection pressures ie new food or temperature.
- Natural selection occurs on each side of the barrier due to the different selection pressures.
- Change in allele frequency as that population evolves (directional selection).
- Populations are no longer able to produce viable young from reproduction if they were to meet again.
- They have become separate species.
How is sympatric speciation different to allopatric speciation?
Sympatric has no geographical isolation
