What is a selective agent?
The Selective Agent is the environmental factor acting on the population.
What is sexual selection?
Type of natural selection where mating preferences influence trait of offspring
What are density dependent factors?
- Predators
- Availability of resources
- Nutrient supply
- Disease
- Accumulation of wastes
What is a selection pressure?
Effect of natural selection acting on population
Example of selective agent
the ability and capacity of an insect to camouflage itself from its predators, like birds or animals, determine its mortality rate
What is the ultimate source of genetic variation?
Mutations, though sexual reproduction and gene flow affect it as well.
What does natural selection act on?
Why?
Natural selection acts on the phenotype of an organism, the observable traits, because this is what interacts with the environment.
What controls the phenotype?
Genotype
What is evolutionary adaptation?
When genotypes best suited to survive and reproduce give rise to a disproportionate share of the offspring.
Overtime, this increases the fitness of the population.
What does natural selection favour?
individuals with phenotypes that are better suited to their environment, making them more likely to survive, reproduce, and pass on their genes to the next generation.
What happens to the population as the individuals with advantageous traits reproduce more successfully?
How does this relate to evolution?
As these individuals reproduce more successfully, the genotypes that produce the advantageous phenotypes become more common in the population over time.
This change in the frequency of alleles within a population is the genetic basis of evolution.
Example of natural selection
For example, in a population of peppered moths, a lighter color phenotype provides an advantage in a clean, light-colored environment as it allows for better camouflage from predators.
The genotypes that code for this lighter color are therefore selected for, and the frequency of these genes increases in the population.
Conversely, in a polluted environment, a darker phenotype provides the advantage, and the genes for the darker color become more common.
Types of adaptations
Structural: Physical appearance
Behavioural: how an organism acts (hibernation, plants blooming at night)
Physiological: Based on body chemistry and metabolism
(Toxins in plants, highly effective kidneys of desert animals)
(Note this is in relation to speciation)
What will differentiate a species from its ancestors?
The demands of a different environment or the characteristics of the members of the new group will differentiate the new species from their ancestors.
What are density independent factors?
- Phenomena (Natural disasters)
- Abiotic factors
- Weather conditions
