Ch 15- Darwin’s Theory of Evolution

1. Ch 15- Darwin’s Theory of Evolution • Evolution- change over time • Process by which modern organisms have descended from ancient organisms • Theory- well supported explanation of phenomena that has occurred in the natural world • Evolution is a theory that has been well tested concept that is supported by evidence

2. Voyage of the Beagle • What was Charles Darwin’s contribution to science? • Made numerous observations and collected evidence-led to revolutionary hypothesis about the way life changes over time • Now supported by large body of evidence • Pattern of diversity • Grassland in Argentina, Australia, and Europe all supported different sorts of organisms

3. Fossils- preserved remains of ancient organisms • Resembled organism living today, others were like no other organisms • Why had so many of these species disappeared? • Galapagos Islands- 1000 km west of South America • Close together, very different climates • Observed the characteristics of many animals and plants varied noticeably among the different islands of Galapagos • Birds’ different shaped beaks • Welcome to Discovery Education Player

4. Lamarck’s Evolution Hypotheses • Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime • Traits could be passed on to offspring • Over time this process leads to change in species • One of first scientists to develop scientific hypothesis of evolution

5. Origins of Evolutionary Thought • Hutton and Lyell- suggested Earth was old enough for evolution to have occurred • Thomas Malthus- suggested human population would continue to grow but sooner or later living space would be insufficient

6. Sec 3- Darwin Presents His Case • 1859 Darwin published his findings in his book, On the Origin of Species- natural selection was the driving force behind evolution • Artificial selection- selection by humans for breeding of useful traits from the natural variation among different organisms • Nature provided the variation, and humans selected the variation they found useful

7. Evolution by Natural Selection • Struggle for existence- members of each species competes regularly to obtain food, living space, and other necessities of life • Predators that are faster can catch more prey • Prey that are faster, better camouflaged can avoid being caught • Fitness- the ability of an individual to survive and reproduce in its specific environment • Adaptation- any inherited characteristic that increases an organism’s chance of survival • Structural characteristics, physiological processes, behavior in animal in which they hunt in groups

8. Survival of the fittest- individuals that are better suited to their environment survive and reproduce most successfully= natural selection • Over time natural selection results in changes in the inherited characteristics of a population • These changes increase a species fitness in its environment • Cannot be seen directly, observed as changes in population over many successive generations • Welcome to Discovery Education Player • Descent with modification- species descend with changes from other species over time • Natural selection produces organisms that have different structures, establish different niches, occupy different habitats • Common descent- all species, living and extinct, were derived from common ancestors

9. Evidence of Evolution • Darwin argued living things have been evolving on Earth for millions of years • Evidence • Fossil record • Geographical distribution of living species • Homologous structures of living organisms • Similarities in early development, or embryology

10. Homologous Body Structures • Homologous structures- structures that have different mature forms but develop from the same embryonic tissues • Provide strong evidence all four limbed vertebrates have descended with modifications from common ancestors • Vestigial organs- organs in animals reduced in size that serve little to no function • Miniature legs, tails