4.4 Genetic diversity and adaptation Flashcards
What is genetic diversity?
Number of different alleles of genes in a population
What are alleles and how do they arise?
● Variations of a particular gene (same locus) → different DNA base sequence
● Arise by mutation
What is a population?
● A group of organisms of the same species in a particular space at a particular time
● That can (potentially) interbreed (to produce fertile offspring)
Explain the importance of genetic diversity
● Enables natural selection to occur
● As in certain environments, a new allele of a gene might benefit its possessor
● By resulting in a change in the polypeptide (protein) coded for that positively changes its properties
● Giving possessor a selective advantage (increased chances of survival and reproductive success)
What is evolution?
● Change in allele frequency (how common an allele is) over many generations in a population
● Occurring through the process of natural selection
Adaptation and selection are major factors in evolution and contribute to the diversity of living organisms
Explain the principles of natural selection in the evolution of populations - mutation
Random gene mutations can result in [named] new alleles of a gene
Explain the principles of natural selection in the evolution of populations - advantage
In certain [named] environments, the new allele might benefit its possessor [explain why] → organism has a selective advantage
Explain the principles of natural selection in the evolution of populations - reproduction
Possessors are more likely to survive and have increased reproductive success
Explain the principles of natural selection in the evolution of populations - inheritance
Advantageous allele is inherited by members of the next generation (offspring)
Explain the principles of natural selection in the evolution of populations - allele frequency
Over many generations, [named] allele increases in frequency in the population
Describe 3 types of adaptations
Natural selection results in species that are better adapted to their environment:
● Anatomical - structural / physical features that increase chance of survival
● Physiological - processes / chemical reactions that increase chance of survival
● Behavioural - ways in which an organism acts that increase chance of survival
Name a type of selection with an example - Directional selection
Antibiotic resistance in bacteria
Organisms with an extreme variation of a trait eg. bacteria with high level of resistance to a particular antibiotic
Name a type of selection with an example - Stabilising selection
Human birth weight
Organisms with an average / modal variation of a trait eg. babies with anaverage weight
What does the graph look like for directional selection?
What does the graph look like for stabilising selection?
