Natural Selection

► How does something like THIS come about?!!

Darwin’s Epic Journey “You care for nothing but shooting, dogs, and rat-catching, and you will be a disgrace to yourself and all your family.”

Observations Aboard the Beagle

Rhea – South America Ostrich - Africa Emu - Australia

Species Vary Locally

Species Vary Over Time 3 m 0.5 m Armadillo Glyptodonts

Putting the Pieces of the Puzzle Together

The Galapagos Islands Darwin was amazed that any wildlife had reached such a remote place, and suspected that the ALL the birds, plants and animals had arrived, during the distant past, from the mainland

Ideas That Shaped Darwin’s Thinking

An Ancient, Changing Earth Geologists James Hutton and Charles Lyell concluded that Earth is ancient and still changing.

Hutton and Geological Change

Lyell’s Principles of Geology

Lamarck’s Evolutionary Hypotheses Jean-Baptiste Lamarck was one of the first naturalists to argue strongly that species are not fixed.

Lamarck’s Theory ► Lamarck believed organisms could adapt within their lifetime to fit their environment, and then pass on their adaptations (ex:fiddler crab) Lamark did not know about mendelian genetics and the rules of inheritance Lamark did not know about mendelian genetics and the rules of inheritance His idea that animals are adapted to their environment did influence Darwin’s ideas on adaptations His idea that animals are adapted to their environment did influence Darwin’s ideas on adaptations Discredited

Population Growth Thomas Malthus reasoned that if the human population grew unchecked, there wouldn’t be enough living space and food for everyone.

Artificial Selection

Darwin’s Dangerous Idea In the same way that dog-breeders and farmers altered the appearance of animals by careful breeding (Artificial Selection), Darwin proposed that there might also a NATURAL mechanism which accomplished the same thing in nature…

Darwin Presents His Case

Darwin’s Observations: 1. organisms produce so many offspring that their population size would increase exponentially if all individuals that are born reproduce successfully 2. populations tend to remain stable in size, except for seasonal fluctuations. 3. environmental resources are limited. POPULATION GROWTH AHA!!!... SURVIVAL OF THE FITTEST Darwin’s Inference: Production of more individuals than the environment can support leads to a struggle for existence, with only a fraction of offspring surviving.

The Origin of Species Darwin knew his ideas were controversial 1858, after reading about Alfred Russell Wallace’s research in the Malay Archipelago, Darwin decided to “go public” with his dangerous idea In 1859, Darwin published his ideas in a book called: “On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life”

“ORIGIN OF SPECIES” In 1859, after 25 years of work, Darwin reluctantly publishes his work to much ridicule. Theory of Natural Selection Darwin proposes that the diversity of life has evolved because the most fit organism in an environment survives and is able to pass on these fitness traits. Adaptations are inherited characteristics which allow organisms to compete for resources and mates in their particular ecosystem. Pinta Island Intermediate shell Hood Island Saddle-backed shell Isabela Island Dome-shaped shell

Darwin Publishes

The Struggle for Existence

Variation and Adaptation Scarlet king snake Eastern coral snake

Adaptations – –Anatomical/structural (flippers on a sea turtle) –Physiological (CAM photosynthesis) –Behavioral (live/hunt in groups)

Survival of the Fittest

Natural Selection

No Such Thing as Perfect

Common Ancestry