Genetic Diversity and Adaptation Flashcards
What is genetic diversity?
The total number of different alleles within a population
What is a gene pool?
The total number of all alleles of all the individuals in a population at a set time
What is allele frequency?
The proportions of the different alleles in the gene pool
What is population?
Group of individuals of the same species that live in the same place
What is a species?
Individuals that can interbreed to produce fertile offspring
What is an allele?
Different forms of a gene
What is natural selection?
The natural process of stronger alleles surviving because they are better adapted to their environment
Therefore breeding which increases the frequency of those advantageous alleles in the next generation
What is reproductive success?
Successfully producing fertile offspring
What is fitness?
Ones that survive to reproduce
Why is having a greater genetic diversity in a population better for its chance of survival?
More variety = more alleles in the population
Therefore with environmental change one individual may have an allele that would allow them to survive
What can happen to populations with a low genetic diversity?
They are very vulnerable
Can lead to a genetic bottleneck eg cheetahs
What changes allelic frequency in a population over time?
Natural selection
Survival of the fittest
As environmental change leads to selection and advantageous alleles survive to reproduce
Therefore allele frequencies will change and only some are passed to the next generation
What decides if an allele is advantageous?
Depends on the environmental conditions at any one time
What are the stages of natural selection?
Variation Mutation Environmental change Competition Survival Reproduction Alleles
What pneumonic helps remember natural selection?
Very Massive Eagles Can Soar Really Aggressively
What are the types of selection?
Directional
Stabilising
Disruptive
What is directional selection?
Selection against an extreme associated with a changing environment
(The graph often shifts left/right and then potentially thinner/fatter)
What is stabilising selection?
Selection against both extremes associated with non-changing/stable environments over many years
Th range and distribution becomes smaller and narrower
Eliminates extreme phenotypes maintaining favourable characteristics enabling a species to be successful
What is disruptive selection?
Selection away from the mean ending up with 2 normal distributions (2 curves)
What is a normal distribution?
A bell shaped curve produced when a certain distribution is plotted on a graph
What is an example of directional selection?
Beak depths
Colour of moths
Antibiotic resistance
What is an example of stabilising selection?
Birth mass of babies
Muscles of Siberian huskies
What is an example of disruptive selection?
Fish population with large and small males that survive
