• Physiological Mechanisms
ECOLOGY – the scientific study of the interactions among organisms and their environments
Phenotypic variation in a population is due to both genotype & environment
Phenotype = Genotype + Environment
- Sometimes Genetic differences among individuals have a greater influence on phenotypic variation in a population
- sometimes Environmental differences that individuals experience have a greater influence.
Heritability: the portion of phenotypic variation in a population due to genetic differences between individuals
Natural selection – is one mechanism of evolution
IF: these three conditions are met
- Phenotypic variation in the population
- some of that
- Interaction with the environment: traits that increase survival and reproduction of individuals increase in frequency.
THEN: adaptive EVOLUTION occurs
Differential survival and reproductive success results from organisms interacting with their environment (Natural Selection).
– Those individuals with traits best suited for the local environment survive, grow and leave more fertile offspring
– This leads to gradual changes in the genetic makeup of a population over the generations. Favorable characteristics accumulate over time.
- Natural Selection acts on individual
- Evolutionary change occurs in population
The result of natural selection is evolutionary adaptation
- So why aren’t organisms “perfectly adapted” to their environments = environment is always changing
– Not all evolution adaptive evolution