Natural Selection Flashcards
Definition of evolution
Gradual change in the inheritable characteristics of a population over time
Why does evolution happen?
Driven by variation (of traits) and competition (for resources) between individuals (of the same species) of a population, leading to differential survival of and reproduction by, organisms which are best fitted to the environment
-mutation creates new alleles and increases the genetic variation in a population results in variation (traits / phenotypes) between individuals
-organisms with selectively advantageous traits are more likely to survive and reproduce
- individuals produce many offspring which results in competition
Examples of environmental factors that can exert a selection pressure
- Biological factors
a. presence of predators
b. presence of pathogens / disease - Resource availability
a. availability of food / water
b. availability of shelter - Physical factors
a. temperature
b. weather conditions
c. natural disasters
Template answer
- selection pressure is exerted by [environmental factor]
- individuals with selective advantageous [traits] are more likely to survive than individuals which do not
- these individuals can reproduce, and pass down their alleles to their offspring
- over many generations there are more individuals with the [advantageous phenotype] in the population