Topic 7 Genetics, Populations, Evolution and Ecosystems - Course Overview Flashcards
What points are assumed in order to use the hardy Weinberg equation to estimate the frequency of alleles in a population?
– No mutations occur to create new alleles
– There is no movement of alleles into or out of the population by migration
– The population population is large
– There is no selection so every allele has an equal chance of being passed to the next generation.
What factors make variation in alleles?
- Random fertilisation – the gout meets that are carrying different alleles were joined together randomly.
- Meiosis– meiosis is the nuclear division that creates gambit and means that the alleles will be assaulted in the gametes at random.
- Mutation – the mutation of an allele can go onto lead to the creation of another new allele which can then be passed to the next generation.
What are the majority of phenotypic traits influenced by?
Environmental influences
E.g. two plants possess the same alleles for the flower colour however one plant lacks mineral from the soil so will develop a slightly different colour.
What will happen to species that share the same niche?
They will be in competition with each other.
What is the idea of better adapted species in natural selection?
They’re more likely to survive.
What is the idea of better adapted species in natural selection?
They’re more likely to survive.
What wheels did Darwin suggest for high levels of offspring being produced?
There will be greater competition within the species (intraspecific) therefore only those that have the alleles best suited to the environments of I’ve long enough to grow and reproduce passing the alleles onto the next generation.
What will increase the chance that species will survive in a changing habitat?
Variation in genotypes and phenotypes.
Summarise the process of evolution via natural selection.
- There’s a variety of phenotypes of a population.
- An environmental change occurs and as a result of that the selection pressure changes.
- Some individuals possess advantages alleles which give them a selective advantage and allow them to survive and reproduce.
- The advantageous alleles are passed to their offspring.
- The frequency of population changes and this leads to evolution.
What are the four different types of selection?
Selection
Directional selection
Stabilising selection
Disruptive selection
What is selection?
The process by which individuals that are better adapted to their environment are more likely to survive and breed. This means they will pass on their advantageous alleles.
What is directional selection?
It occurs when the environmental conditions change and the phenotypes best suited in the new conditions are more likely to survive as a result. These individuals will breed and produce offspring overtime. The meaning of the population move in the direction of these individuals.
What is stabilising selection?
The Phoenix types with successful characteristics are preserved and those of greater diversity are reduced. This selection doesn’t occurs due to the changes in the environment. If the environment stays the same then the individuals closest to the mean are favoured.
What is destructive selection?
This is the opposite of stabilising selection and in this case both extremes of the normal distribution are favoured over the mean.
What is allopatric speciation caused by?
A physical barrier - as the two groups become separated they become reproductively isolated.
