What is Evolution? What is Evolution?

EVOLUTION: the process of change over time Evolution is the idea that new species develop from earlier species by accumulated changes.

Charles Darwin The Father of Evolution A scientist that traveled the world making observations and collecting evidence about the way life changes.

Darwin’s Travels §He sailed from England as a crew member on the H.M.S. Beagle §Wherever the ship anchored, Darwin went ashore to collect plant and animal specimens that he added to his research collection.

Darwin’s Travels cont.. §Darwin selected the Galapagos Islands for study because each island had different climates and a variety of animal and plant life. §Darwin observed that the characteristics of many animals and plants differed greatly among the different islands.

The Origin of Species §Darwin’s book presented evidence that evolution has been taking place for millions of years and continues in all living things

Darwin's Hypothesis: “Survival of the fittest” (not necessarily the strongest): Those with more adaptive traits tend to survive longer and/or produce the most offspring.

Artificial Natural SelectionSelection §Selections by humans for breeding useful traits from the natural variations among different organisms §Individuals better suited to their environment survive and reproduce most successfully

Artificial Selection How did humans in relatively short time produce dogs that are so radically different from the wolf and each other? §Sometimes, dogs are born with unusual traits—short, stubby legs, for example. §In nature, this trait might be harmful but under the care of humans, this trait may be desirable, so humans will keep the dog alive and use it to produce more dogs with short stubby legs.

Natural selection is based on 4 facts: 1.Organisms produce more offspring than can survive. 2.There is variation among offspring. 3.There are limited resources (not enough food, water, space, etc. for everyone). 4.The organisms best fit to their environment will survive and the others will not.

Evidence of Evolution §Fossils are preserved remnants or impressions left by an organism that lived in the past. §The deeper down the fossil is, the older it is.

FOSSIL RECORDS §The fossil record provides evidence about the history of life on Earth. §It also shows how different groups of organisms, including species, have changed over time.

Homologous Structures Structures that have different shape and functions in different organisms but develop from the same embryonic tissues. §Examples: The limbs of the modern HUMAN, BIRD, PORPOISE and ELEPHANTS are homologous structures because they possess the same bones but these bones perform different jobs.

Adaptations: Inherited characteristic that increase an organism’s chance of survival §Why are most animals in the artic white? l So they blend in with the snow and avoid being seen §Why do sharks have such sharp teeth? l It allows them to catch their prey §Why do elephants have such big ears? l To let heat escape their bodies so they can stay cool

Vestigial Organs organ that serves no useful function over generations, they reduce in size Whale Human Appendix

DARWIN’S Theory Of Evolution 1.Differences between species may be the result of natural selection. 2.Organisms produce more offspring than can survive, and many that do survive do not reproduce. 3.Because more organisms are produced than can survive, they compete for limited resources. 4.Individual’s best suited to their environment survive and reproduce most successfully. 5.Species change over time.

Gene Pool §All genes, including all the different alleles presents in a population

Genetic Variations §Two main sources of genetic variation are mutations and the genetic shuffling that results from sexual reproduction

5 Conditions for maintaining genetic equilibrium: 1.Random mating 2.Population must be very large 3.There can be no movement into or out of the population 4.No mutations 5.No natural selection

Results of Evolution -- Speciation!! §Speciation is the process that creates new species! §A species is a group of organisms that can naturally interbreed and produce fertile offspring. §The Liger--the offspring of a tiger and a lion. §Tigers and lions are still considered separate species, because although they can produce offspring, the offspring is not fertile.

ENDOSYMBIOTIC THEORY §Theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms. A group of single celled organisms came together to make a multicellular organism.

Types of Evolution §Convergent Evolution process by which unrelated organisms independently evolve similarities when adapting to similar environments. Ex.. Sharks, Penguins & Dolphins

Types of Evolution §Coevolution process by which two species evolve in response to changes in each other. Ex.. Humming Birds & Flowers

Extinction! §Extinction occurs when there are no members of a species left alive.