Introduction, Evolution

Introduction, Evolution

Topics

• Physiological Mechanisms
• Genetics
• Development
• Evolution

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 

  1. Phenotypic variation in the population
  2. some of that
  3. 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

 

 

 

 

 

 

Photo by woodleywonderworks is licensed under CC BY 2.0


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