Genetic diversity, species and taxonomy (ARN) Flashcards
What is meant by genetic diversity?
The total number of different alleles in a population
What is an allele?
A variant or form of a gene that occupies the same position (locus) on homologous chromosomes.
What is a population?
A group of individuals of the same species that live in the same place and can interbreed.
What is a species?
A group of organisms that can interbreed and produce fertile offspring.
What is a selection pressure?
An environmental change that affects the chance of survival of individuals in a population
How does genetic diversity affect a population’s resistance to selection pressures?
The greater the genetic diversity, the more resistant a population is to selection pressure, as the wide range of characteristics in the population means it is more likely that an individual possesses a trait that can suit new environmental change.
What is natural selection?
The process where individuals with traits better suited to their environment are more likely to survive, reproduce, and pass on those advantageous traits, leading to changes in the genetic makeup of a population over time.
What is evolution?
A change in the genetic makeup of a population over time, driven by natural selection, where advantageous traits become more common due to increased survival and reproduction
How do populations evolve?
Random mutations of alleles can lead to an advantageous trait that is better adapted to the environment. Individuals with this trait are more likely to survive in competition with others, and live long enough to reproduce and pass on the advantageous trait to the next generation. Over many generations, the number of individuals with the advantageous alleles increases at the expense of those with less advantageous alleles, as they have a greater chance of surviving and reproducing.
What is a phenotype?
The observable physical and biochemical characteristics of an organisms
What is classification?
The organisation of living organisms into groups
What are the two types of classification?
Artificial and phylogenetic
What is artificial classification?
It divides organisms according to observable, non-evolutionary characteristics, like colour or size, rather than evolutionary relationships.
What is phylogenetic classification?
Classification based upon:
- Evolutionary relationships between organisms and their ancestors
- Classification of species based on shared features derived from their ancestors
- Arrangement of organisms into hierarchies
What is a hierarchy
A group within a group that doesn’t overlap
What is a homologous characteristic?
Characteristics that have similar evolutionary origins, regardless of their function
What is meant by a polygenetic trait?
A trait that is controlled by more than one gene
What is directional selection?
Directional selection favours individuals with extreme phenotypes. It results is phenotypes at one end of the extreme being selected for and those at the other extreme being selected against
What does directional selection do to the shape of a distribution curve?
Shifts the peak towards the extreme that is being favoured
What is stabilising selection?
Stabilising selection favours individuals closest to the mean, when environmental conditions remain stable. Phenotypes around the mean are selected for and those at the extremes are being selected against.
What does stabilising selection do to the shape of a distribution curve?
Makes the graph taller and slimmer, which the peak in the same place
What are anatomical adaptations?
Physical features of animals that have evolved to enhance their survival.
What are behavioural adaptations?
Actions that organisms exhibit to increase chances of survival
What are physiological adaptations?
Internal body processes that regulate and maintain homeostasis for an organism to survive in their environment.
