4.4 Genetic diversity and adaptations Flashcards
What is a species
A group of organisms with similar characteristics that can breed together to produce fertile offspring.
What is genetic diversity
The number of different alleles in a population of a species.
What is a population
A group of individuals of the same species that live in the same place and can interbreed.
Why is a high genetic diversity beneficial
It means there is greater variation, so more individuals are likely to survive if the environment changes.
What is evolution
A change in allelic frequencies of a population over time.
What is natural selection
The process through which evolution occurs which may result in the formation of a new species.
What are 5 reasons why natural selection/evolution takes place
- Natural variation
- Selection pressures
- Natural selection#
- Hereditability
- Time
What is a selection pressure
Environmental factors that affect chances of survival and successful reproduction.
What are some examples of selection pressures
- Competition (for food, water, space, mates,etc)
- Presence of predators
- Disease
- Extreme temperatures
- Natural disasters
How does natural selection cause evolution to take place
- Some traits are adaptive
- Some traits are maladaptive
- Organisms with adaptive traits are more likely to survive and reproduce than those with maladaptive traits
What is an adaptive trait
A trait that increases the chance of survival and/or reproductive success in current environment.
How does hereditability result in evolution
- Some traits are passed from parents to offspring
- Organisms with adaptive traits are more likely to reproduce
- Adaptive traits are more likely to be passed on than maladaptive traits
How does time result in evolution
The next generation on average are very slightly better adapted than the parents.
Explain the process of evolving a certain trait (e.g. explaining why giraffes have long necks)
- Random mutations occur which leads to new alleles and genetic variation among giraffes
- A new selection pressure is exerted by a change in the giraffes environment
- There is competition for survival due to the selection pressure
- Individuals with advantageous alleles (alleles which code for proteins that grow a longer neck) are more likely to survive
- These individuals reproduce and pass on the advantageous alleles
- Over time this increases the frequency of the allele in the population
- Therefore there is a decrease in frequency of non-advantageous alleles
What are 3 types of adaptation
- Anatomical
- Behavioural
- Physiological
What is an anatomical adaptation
Physical adaptations, e.g. shorter ears and thicker fur in arctic foxes compared to foxes in warmer climates.
What are behavioural adaptations
Changes in behaviour which increase the organisms chance of survival, e.g. oxidising fat rather than carbohydrate in kangaroo rats to produce additional water in a dry desert environment.
What are physiological adaptations
Processes inside an organisms body that increase its chance of survival, e.g. autumn migration of swallows from the UK to Africa to avoid food shortages in the UK winter.
What do courtship behaviours do
They increase the rate of successful mating and eventual reproduction.
What are 4 reasons why animals have courtship behaviours
- Ensure mating occurs between individuals of the same species but opposite gender
- Allow identification of mates capable of breeding (fertile, sexually mature)
- Form a pair bond (some species mate for life, this will lead to successful mating and raising of offspring)
- Synchronise mating. Displays and scents can be used to stimulate gamete release.
What is a genotype
The genetic constitution of an organism.
What is a phenotype
The expression of this genetic constitution and its interaction with the environment.
What is a polygene
- Characteristics that are influenced by more than one gene
- The more polygenic a phenotype, the greater the effect of environmental interaction upon the phenotype
What do polygenetic characteristics produce
A normal distribution curve.
