u4aos2 Flashcards
how are species related overtime
Calculation of Allele Frequencies
The percentage of a particular allele in a population
Mutation
The changes in DNA are the source of new alleles in a gene pool.
Germline mutations
Mutations that are inheritable as they affect gametes (sperm and egg cells) and therefore can be passed down to offspring.
Somatic mutations
Mutations that occur in body cells and only affect the individual that consists it.
Natural Selection
The reproduction of individuals who are well-suited to their environment and more likely to survive, passing on their strong genes.
2 types of Selection Pressures
- Environmental Pressure
- Artificial Pressure
Environmental Pressures
External pressures that affect individuals in a population differently.
Genetic Diversity
xThe differences in individuals in terms of their phenotype.
Reproduction
The differences in individuals in terms of their reproductive success.
Survival
The differences in individuals in terms of their rates of living
Adaptive Value
The advantage that some individuals have over others due to their strong phenotypes (known as survival of the fittest)
Gene Flow
The transfer of alleles between populations.
Genetic Drift
The random change in allele frequencies due to chance events. (mostly in terms of small populations)
Founder Effect
The genetic isolation of a small group of individuals from a population.
Bottleneck Effect
The sudden and substantial reduction in a population’s size.
Selective Breeding
Humans decide which individuals may breed and leave offspring for the next generation.
Selective Breeding in Plants
Take seeds from a plant with desirable traits and those seeds are planted or cross -pollinated for the new generation.
Selective Breeding in Animals
Interbreeding individuals to propagate desirable traits.
- sheep for quality/quantity of wool.
- cows for milk production
Advantages of Selective Breeding
(5 points)
- higher yield of goods.
- healthier products
- survival in unsuitable conditions
- more nutrients are provided
- new variation of species
Disadvantages of Selective Breeding
(3 points)
- Reduces resistance to environmental changes
- Reduces biodiversity
- increases genetic abnormalities
Gene
A sequence of DNA that codes for a trait/characteristic
Alleles
The different variations of genes
Genotype
Various combinations of alleles. The coded version of a gene.
Phenotype
The observable traits. The physical appearance of a gene.
Gene pool
The total number of diversity in a population.
The total number of alleles in a population.
Genetic diversity
the variations of genes and alleles in a population.
Genome
All the genetic information in an organism.
Polygenic trait
A characteristic that is influenced by two or more genes.
Reproductive success
The rate at which individuals can reproduce. More reproduction = more successful.
Biological Fitness
The ability for an organism to survive and reproduce healthy offspring.
Adaptations
Traits that are well suited to an organisms environment.
Evolution
The change in genetic composition of populations overtime.
Species
a group of individuals that genetically similar enough to interbreed and produce viable offspring that are able to reproduce.
Interbreeding
The reproduction between individuals that belong to the same species or closely related species.
viable offspring
offspring that are fertile and able to survive and breed for the next generation.
genetic isolation
occurs when alleles are no longer exchanged within populations.
2 types of genetic isolation
- Prezygotic isolation (before reproduction)
- Postzygotic isolation (after reproduction)
Prezygotic isolating mechanisms
