BIOCHAP9B Flashcards
Environmental selection pressure:
factors in env that impacts an organism’s ability to survive and reproduce
Competition:
interactions between organisms in which both are negatively impacted .
Natural selection:
organisms that are better adapted to their environment have an increased chance of surviving and passing on their alleles.
Fitness:
measure of how well an organism survives and reproduces in its environment.
Advantageous phenotype:
biochemical, physical, or behavioural trait that increases an organism’s fitness in its local environment
Selective advantage:
an organism conferred a beneficial allele, which increases its chances of survival
Disadvantageous allele:
allele that encodes for a biochemical, physical, or behavioural trait that lowers an individual’s fitness .
Common examples of environmental selection
pressures
Predation
Disease
Competition
Climate change.
Through these factors,
natural selection can occur, involves the selection of the phenotype most suited to overcome the environmental selection pressure.
Four conditions of natural selection
Variation: indiv in pop vary genetically, phenotypic differences
selection pressure: env sel pressure impacts surviavability within pop and ability to reroduce
selective adv
heritability: adv trait must be heritable, allowing to pass from parents to offspring
The effects on genetic diversity
- ESP determine which pheno are fitter an adv
-when adv traits become common, frequencis change increasing-evolution of species can occur
plants
if light is limited, larger leaves are selected bc they can absorb more light. the allele frequencies of the allele coding for larger leaves will increase this process leads to a decrease in genetic diversity within the population.
Survivability of a species
A population with a greater variation in alleles has a higher chance of possessing a favourable allele that will help them survive if a new selection pressure arises
