Ch. 15: Evolution - change in a species or the formation of new species over time

Ch. 15: Evolution - change in a species or the formation of new species over time

15.1 Darwin

Early Beliefs All species permanent and unchanging Earth only a few thousand years old religion Beliefs based on

Georges Cuvier Found evidence that: Ancient organisms very different Some stopped existing: Extinction Catastrophism sudden geological events caused extinction

Charles Lyell Geologist Uniformitarianism : Earth's surface has been changed by geological processes ex: earthquakes, volcanic eruptions

Thomas Malthius Economist Stated that: 1. Nature over produces offspring 2. Overpopulation could destroy the earth 3. Forces that prevent overpopulation: a. Disease b. Starvation c. War

Jean Baptiste Lamarck Believed in evolution His explanation of how evolution occurred : wrong was Inheritance of acquired characteristics Traits acquired during life passed to offspring ex: passing big muscles on to offspring

Charles Darwin 1830's Famous evolutionary biologist Described evolution as Descent with Modification - new species descend from pre-existing species ex: Galapagos Finches (13 species) from 1 ancestor

Darwin's Finches

How does evolution occur? Natural Selection 1. Overproduction: - species over produce young 2. Genetic Variation: - some organisms inherit traits which improve/harm survival: - ex: strength, disease resistance

3. Struggle to Survive - organisms compete to survive/mate - some have Adaptations: trait that makes individual more likely to survive & mate

4. Differential Reproduction - those w/ best adaptations survive & reproduce - trait passed on to offspring - population changes as traits become more common - shows Fitness: measure of individual's genetic contribution to next generation

Peppered Moths: Natural Selection at work

15.2 Evidence of Evolution

Evidence of Evolution Fossils Remains or traces of organisms that lived long ago Best evidence of evolution: shows life has changed often found in rock strata (layers)

Principle of Superposition Proposed by Nicholas Steno In undisturbed rock layers, oldest layer is on bottom; newer layers on top

Transitional Species have features between ancestors and descendants ex: whales: ancestor was 4 legged

Transitional Whale Species

Anatomical Evidence 1. Homologous Structures: similar anatomy in different species Indicates a common ancestor Human, penguins, alligators & bats have forelimbs w/ homologous bones

2. Analogous Structures Structures with similar functions DO NOT come from common ancestor Bats, birds & moths all have wings, but wings have different parts evolved separately

3. Vestigial Structures Serve no function but resemble functional structures in related organisms ex: human s tailbone, whale s pelvis

Embryological Evidence At certain stages, developing embryos look a lot alike Indicates evolutionary relationships The longer embryos look alike, the closer the organisms are related

Molecular Evidence Similarities in DNA, RNA, & proteins indicate evolutionary relationship More similarities = closer relationship Human & Chimp DNA is 96% identical!

15.3 Evolutionary Patterns

Patterns of Evolution 1. Convergent Evolution Different species evolve similar traits as they adapt to same kind of environment Causes Analogous structures to form ex: evolution of wings for flight

Convergent Evolution

2. Divergent Evolution Descendants of common ancestor become more different as each adapts to own environment Causes Homologous structures to form ex: anole lizards

Divergent evolution

3. Adaptive Radiation Happens to a population in new environment rapid divergent evolution until population fills all parts of environment ex: Darwin's Finches: 13 species from 1 ancestor

4. Co-evolution 2 or more species evolved together Can be beneficial to each species ex: flowers & their pollinators

5. Artificial Selection Divergent evolution caused by humans Selective breeding: choosing best organisms to breed ex: human caused dogs to evolve from wolves15,000 years ago 1 species to 600 subspecies

Resistance Bacteria have evolved to become resistant to antibiotics Divergent evolution Due to misuse & incorrect use of antibiotics Creates superbugs : ex: MRSA