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Early history of Earth Earth is thought to have formed about 4.6 billion years ago. Oldest rocks are about 3.9 billions years old. About 3.5 billion years ago, the first living organisms appeared. Bacteria, Prokaryotic, Anaerobic Fossils Fossils: any preserved remains of an organism that lived long ago. Paleontologists Scientists who study ancient life Relative dating technique Based on the premise that the deeper an organism is buried in sediment, the older it is. Spontaneous generation Aristotle proposed the theory of spontaneous generation. The idea that life was produced from nonliving matter. Idea lasted almost 2000 years Francisco Reid In 1668, he disproved the theory of spontaneous generation of larger organisms. Evidence against spontaneous generation: 1. Unsealed – maggots on meat 2. Sealed – no maggots on meat 3. Gauze – few maggots on gauze, none on meat Biogenesis Louis Pasteur In the mid-1800s, he disproved the “air theory” and established the concept of biogenesis. The idea that living organisms come only from other living organisms. John Lamarck 1809 One Of First Scientists To Understand That Change Occurs Over Time Stated that Changes Are Adaptations To Environment acquired in an organism’s lifetime Said acquired changes were passed to offspring Lamarck’s theory of evolution Idea called Law of Use and Disuse If a body part were used, it got stronger If body part NOT used, it deteriorated Blacksmiths & Their Sons (muscular arms) Giraffe’s Necks Longer from stretching) Inheritance Of Acquired Traits Traits Acquired During Ones Lifetime Would Be Passed To Offspring Clipped ears of dogs could be passed to offspring 11 Lamarck’s Mistakes Lamarck Did NOT Know how traits were inherited (Traits are passed through genes) Genes Are NOT Changed By Activities In Life Change Through Mutation Occurs Before An Organism Is Born Evolution A change in a population of organisms over time Charles Darwin Scientist who is considered the founder of modern evolutionary theory. Astounded by variety of life (biodiversity) Naturalist Charles Darwin Darwin used his theory of natural selection to explain how organisms evolve. HMS Beagle’s Voyage In 1831, he sailed on the HMS Beagle to South America & the South Pacific and returned 5 years later. The Galapagos Islands Small Group of Islands 1000 km West of South America Darwin studied & compared the anatomy of many organisms. Very Different Climates Animals On Islands Unique Tortoises Iguanas Finches The Galapagos Islands Island species varied from mainland species & from island-to-island species Each island had long or short neck tortoises The Galapagos Islands Finches on the islands resembled a mainland finch More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) Finches had different types of beaks adapted to their type of food gathering Natural selection The process by which individuals that are better adapted to everything around them survive and reproduce more successfully. Natural selection Those with less favorable variations are less likely to survive and pass on traits to the next generation. Each new generation is largely made up of offspring from parents with the most favorable variations. Natural selection is also known as “the survival of the fittest.” Natural Selection is driven by 4 important points: 1. All populations have genetic variation 2. The environment presents challenges to successful reproduction Naturally, an organism that does not survive to reproduce or whose offspring die before the offspring can reproduce does not pass its genes on to future generations. 3. Individuals tend to produce more offspring than the environment can support. Individuals of a population often compete with one another to survive. 4. Individuals that are better able to cope with the challenges presented by their environment tend to leave more offspring than those individuals less suited to the environment. Adaptation An anatomical, physiological or behavioral trait or characteristic that improves a population’s ability to survive. Evidence for evolution The following provide evidence for evolution: 1. 2. 3. 4. Fossil Records Anatomical Studies (homologous, analogous, vestigial) Embryological development Biochemistry: DNA Sequences Fossil evidence Scientists use fossil records to understand the general pathway of evolution. A model of evolution from small-toed to one-toed horses. Anatomical studies Homologous Structures are…. Similar structures that show a common ancestor. Anatomical studies An analogous structure is any body part that is similar in function but different in structure. Example: Insect and bird wings have the same function but are not similar in structure (bird wings are made up of a set of bones while insect wings are mainly made of chitin). Anatomical studies A vestigial structure is any body structure that is reduced in size and function in a living organism but may have been used in an ancestor. Legs on skinks Appendix in humans Pelvic bones of a baleen whale. Embryological development In the earliest stage of embryological development in a fish, reptile, bird and mammal, a tail and gill slits can be seen in all species. As development continues, the embryos become more & more distinct, & in the stages before birth, they attain their distinctive forms. Biochemistry Scientists use DNA, RNA and proteins to determine levels of relationships among species within major taxonomic groups. Speciation It is the process by which a new species is formed. This can only occur when either interbreeding or the production of fertile offspring is somehow prevented. Isolation and divergence can lead to speciation. Patterns of evolution Divergence is the build up of differences between groups of living things as a result of natural selection Divergence leads to the formation of new species Types of isolation Geographic isolation occurs if a physical barrier separates a population into groups. Reproductive isolation occurs when formerly interbreeding organisms are prevented from producing fertile offspring. Speciation rates (evolution tempos) Gradualism is the idea that species originate through a gradual buildup of new adaptations. It is supported by fossil evidence, such as those for the slow & steady buildup of adaptations of camels & horses. Speciation rates (evolution tempos) Punctuated equilibrium states that speciation occurs quickly in rapid bursts, with long periods of stability in between. Patterns of evolution Convergent evolution is the process by which unrelated species become more similar as they adapt to the same kind of environment. Evolution of pesticide resistance Selection against small guppies results in an increase in average size Other Vocabulary Gene Flow – the movement of genes into or out of a population due to interbreeding Genetic Drift – the random change in allele frequency in a population