Darwin’s Theory of Evolution The Origin of Species by Natural Selection

Who was Charles Darwin?

Journey of the Beagle 1831 – 1836 Darwin was appointed companion to the captain, and self-appointed naturalist. He spent time ashore collecting plant and animal specimens

Ideas that shaped Darwin’s thinking James Hutton (1788) first suggested that the Earth is millions (not thousands) of years old. Geological processes operate extremely slowly. Charles Lyell (1833) added that processes can be observed today, and must also explain past events. Thomas Malthus (1798) observed that more organisms are born than can be supported. Populations are kept in check by famine, war, and disease

Jean-Baptiste Lamarck (1809) theory of the inheritance of acquired traits - parts used or disused could be changed during an organism’s lifetime, and passed on to offspring. * First to recognize that organisms change over time; are adapted to their environments, and are descended from common ancestors

Alfred Wallace In 1858 he wrote to Darwin, proposing the same idea of evolution by natural selection In 1859 Darwin published his theory of evolution by natural selection

Darwin in the Galapagos Islands: DIVERSITY

DIVERSITY He saw a great diversity of organisms there.

Darwin’s observations:DIVERSITY 68 different species of beetles in a Brazilian rainforest in one day

13 different species of finches on the Galapagos Islands = DIVERSITY

Diversity: It is estimated that there are more than 20 million different species on the Earth today. 99.9 % of all species that have ever lived are now extinct. How do we explain such diversity, and why have so many organisms disappeared, and so many new ones appeared?

Adaptation: any inherited characteristic that increases an organism’s chances for survival Ground finches: crush seeds with beaks Cactus finch: eat small insects from flowers or cactus] Tree finch: feed mainly on insects Wood pecker finch: uses twigs to pry insects or larvae out

Adaptions Camouflage

Adaptions Mimicry

Fitness: the physical traits and behaviors that enable organisms to survive in their environment. a long neck, a sharp bill and bright blue feet. elaborate mating ritual : the male raises one blue foot in the air, then the other, as he struts in front of the female. http://www.nhptv.org/natureworks/bluebooby.htm

30 years after the voyage, Darwin published his book (1859): The Origin of Species by Natural Selection Modern organisms were produced by a process of evolution (change over time) All organisms have arisen from preexisting organisms If you look back far enough in time, you will find common ancestors

Theory of Natural Selection Variation: genetic variation in a population Heritability: genes are inherited Overproduction: populations produce more organisms than can survive Reproductive Advantage: Organisms with traits suited for environment survive and reproduce more. SURVIVAL OF THE FITTEST

Artificial Selection Selective Breeding Breeder chooses traits and breeds organisms with these traits in order to produce desired offspring Domesticated dogs bred from wolves Wolves with selected traits bred together over generations to produce different breeds

Evolution of Resistance Ability to break down certain chemicals (antibiotics, pesticides) into harmless molecules Bacteria have evolved resistance to many antibiotics due to overusage by humans Organisms with genes to be resistant to chemicals survive and reproduce passing on resistance to their offspring

The faster an organism reproduces, the faster its populations can evolve

Evidence for evolution: 1. age of the Earth (4.5 bya) James Hutton (1788): natural processes such as rain, cold, heat, wind, volcanoes, operate slowly, over millions of years Charles Lyell (1830): forces operating on the Earth can still be seen today.

Evidence for evolution: 2. fossils Fossils: preserved remains of ancient organisms Show great diversity of organisms that no longer exist Show gradual and successive changes

a. Transitional fossils Show link between species; have features shared by different species Archaeopteryx- feathers of bird; teeth, bony tails of reptiles

b. Fossil record All fossils of living organisms that have been found Show ancient species share similarities with modern species Not all organisms have fossils- incomplete

c. Law of Superposition Younger rock layers on top of older Sedimentary Rock- fossils form easily

d. (Radioactive dating) Uranium 238 4.5 billion years Potassium 40 1.3 billion years Carbon 14 5770 years Radioactive elements decay at a steady rate. A half-life is the amount of time needed for half of the atoms in a sample to decay.

Evidence from living organisms: 3 Evidence from living organisms: 3. embryological vertebrate embryos are similar due to similar genes, common ancestor

Structures are similar, functions are different Evidence from living organisms: 4. Morphological Evidence (Anatomical): a. Homologous Structures Structures are similar, functions are different Must have evolved from a common ancestor structures that are similar in structure but may serve different purposes. They suggest common origin

Organs inherited from ancestors, but having no apparent function Evidence from living organisms: 4. Morphological evidence: b. vestigial organs Organs inherited from ancestors, but having no apparent function Organs that appear in the embryo but are lost later in development Organs that have no apparent function, or that may appear in the embryo but are lost later in development

Evidence of Evolution: 4. Morphological evidence:. c Evidence of Evolution: 4. Morphological evidence: c. Analogous Structures Structures with the same function, but different structures Not closely related animals Environment controls adaptations

Evidence in living organisms: 5. Biochemisty: chemical compounds All living organisms have some compounds in commmon DNA and ATP RNA Cytochrome C

Evidence in living organisms: 6. Geographic Distribution Organisms in different parts of the world are very similar Due to separation of continents and organisms evolving adaptations to their environment

Evidence in living organisms: 6. Geographic Distribution