Evolution and Darwin

Evolution processes earliest forms diversityThe processes that have transformed life on earth from it’s earliest forms to the vast diversity that characterizes it today. changegenes!!!!!!!!A change in the genes!!!!!!!!

Old Theories of Evolution Jean Baptiste LamarckJean Baptiste Lamarck (early 1800’s) proposed: “The inheritance of acquired characteristics” develop characteristics passesoffspringHe proposed that by using or not using its body parts, an individual tends to develop certain characteristics, which it passes on to its offspring.

“The Inheritance of Acquired Characteristics” Example:Example: A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

Lamarck was NOT correct because the genetic material was not changed! “ The Inheritance of Acquired Characteristics ”

Cut off the tails of 22 generations of mice The succeeding generations all developed the long tail trait Disproved Lamarck’s acquired characteristics August Weismann

Charles Darwin Influenced by Charles Lyell “Principles of Geology”.Influenced by Charles Lyell who published “Principles of Geology”. DarwinThis publication led Darwin to realize that natural forces gradually change Earth’s surface and that the forces of the past are still operating in modern times.

Charles Darwin H.M.S. Beagle (mainly South America and the Galapagos Islands)Darwin set sail on the H.M.S. Beagle ( ) to survey the south seas (mainly South America and the Galapagos Islands) to collect plants and animals. Galapagos Islands,On the Galapagos Islands, Darwin observed species that lived no where else in the world. These observations led Darwin to write a book.

Charles Darwin Wrote in 1859Wrote in 1859: “On the Origin of Species by Means of Natural Selection” Two main points:Two main points: 1.Species were not created in their present form, but evolved from ancestral species. 2.Proposed a mechanism for evolution: NATURAL SELECTION

Darwin Believed species changed over time to adapt to their new environment. Studied finches in the Galapagos for speciation

Darwin’s Theory of Evolution

Overproduction Organisms produce too many offspring

Competition Offspring have to compete for limited resources

Faster Stronger Smarter Characteristics differ between members of the same species Variation Adaptations Due to variations, some individuals will inherit an advantage to survive in their environment.

Natural Selection The environment selects the “most fit” organisms to survive and reproduce. Therefore these favorable traits have the best chance of being passed on. Nature Selected Against Nature Selected Against

Speciation Over many generations, favorable adaptations accumulate until a new species is formed.

Darwin thought evolution to occur slowly and continuously over millions of years gradualism Punctuated equilibrium are long periods of stability followed by short, quick periods of change. Takes hundreds of thousands of years. How fast is evolution?

MODERN EVOLUTION Natural selection drives evolution…but so does variation. What is the source of variation?

Lesson plans for teaching about microevolution Mutations Can be favorable  increase in frequency Can be unfavorable  decrease in frequency

Speciation

Geographic Isolation

Many bacteria, with only one resistant to antibiotic X Population being exposed to antibiotic X Small population of survivors, with one resistant Recovered population, with many resistant bacteria Observed Natural Selection Examples: Antibiotic resistant strains of bacteria Pesticide resistant strains of insects