Theory of Evolution

Lamarck Law of use & disuse Inheritance of acquired characteristics

Lamarck’s hypothesis Rejected, attacked, proved incorrect Lamarck First to state that organisms do change over time New types of organisms are descended from slightly different organisms

Natural Selection Mid-1800’s Charles Darwin and Alfred Wallace Independently proposed that species were modified by natural selection best suited to environment reproduce more Over generations, favorable traits increase in a population

Darwin’s Data Trekked hundreds of kilometers Collected many types of organisms Observed thousands of species 13 similar but separate species of finches collected from the Galapagos Islands Distinctive bill Specialized for a particular food source Similarities between finches implied a common ancestor

Evolution Occurs due to Modification by Natural Selection Darwin The environment limits the growth of populations Competition Predation Overproduction Adaptations Variations Natural Selection

Evolution Occurs due to Modification by Natural Selection The environment may affect individual organisms in a population in different ways Individuals of a species are not identical Some will have traits that make them better able to cope w/ the environment Natural Selection Organisms with favorable traits will leave more offspring than organisms that don’t have as many favorable traits Populations adapt to the environment

Evolution Occurs due to Modification by Natural Selection Trait that will be passed on One that allows organism to reproduce more successfully One that is inherited Allows a population to adapt to their environment Proportion of good genes increases The change in the genetic makeup of a population is evolution

Evolution Occurs due to Modification by Natural Selection Organism with high fitness Well adapted to environment Contributes genetically to the next generation Reproduces more successfully

Evolution Occurs due to Modification by Natural Selection Not an active process Organisms cannot purposely acquire favorable traits Environment “selects” the favorable traits Ability to run fast Camouflage Strength Traits that are favorable in one environment may not be favorable in another environment Favorable traits give organisms an adaptive advantage