Background on Charles Darwin • As a youth, Darwin struggled in school • Father was a wealthy doctor • At age 16, Darwin entered school to study medicine but was horrified by surgery • Darwin’s interests lay with the natural sciences • 1827, Darwin was sent to Cambridge University to become a minister.
Darwin’s Voyage • 1831, Darwin’s professor recommended him as an unofficial naturalist on a voyage on the HMS Beagle.
Darwin’s contributions • Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors.
Patterns of biodiversity • 1. Species vary globally • Noticed that different, yet ecologically similar animal species inhabited separated but ecologically similar habitats around the globe • Ex. Flightless birds , the rhea of South america, the ostriches on Africa, the emu on Australia
Patterns of Biodiversity • 2. Species vary locally • Noticed that different, yet related, animal species often occupied different habitats within a local area. • Tortoises – shells designed for where they live and what they eat.
Patterns of Biodiversity • 3. Species vary over time • Noticed that some fossils of extinct animals were similar to living species. • Fossil record • Glyptodont and the armadillo
Darwin’s voyage • Sailed on Dec. 27, 1831 • 5 years, collect samples, took many observations • 1859, published his ideas in a book called “On the Origin of Species by Means of Natural Selection”
Influences • In Darwin’s Day, the thought was that the earth was only a few thousand years old and not much had changed. • Geologist James Hutton - - hypothesis on how geological processes have shaped the Earth. • Proposed forces beneath Earth’s surface can push rock layers upward, over long periods of time = mountain ranges
Charles Lyell • Wrote Principles of Geology in 1830, building off the work of Hutton • Geological processes we see today mush be the same ones that shaped Earth millions of years ago.
Jean Baptist Lamarck • Suggested organisms could change during their lifetimes by selectively using or not using various parts of their bodies. • Pass acquired traits on to their offspring, enabling species to change over time = inheritance of acquired traits • Ex. Giraffe neck • Why was this proven wrong??
Thomas Malthus • Economist • Reasoned that if the human population grew unchecked, there wouldn’t be enough living space and food for everyone. • This does not happen, why? • Darwin realized that most organisms do not survive and reproduce, which do and why… survival of the fittest.
Artificial Selection • Nature provides the variations and humans select those they find useful • Ex. Breeding horses, dogs… • Darwin realized that the natural variations among individuals was very important because it provided raw material for change…evolution!
Evolution by Natural Selection • 3 points that went into Darwin’s theory • The struggle for existence • Variation and adaptation • Adaptation – any heritable characteristic that increases an organism’s ability to survive and reproduce in its environment. • Survival of the fittest – • How well an organism can survive and reproduce in its environment.
Natural Selection • Process by which organisms with variations most suited to their local environment survive and leave more offspring.
Descent with modification • Darwin suggested that over many generations, adaption could cause successful species to evolve into new species. • Principle of common descent – all species, living and extinct- are descended from ancient common ancestors.
Evidence for Evolution • Biogeography – study of where organisms live now and where they and their ancestors lived in the past. • Patterns in the distribution of living and fossil species tell us how modern organisms evolved from their ancetors
Fossil Evidence • Many recently discovered fossils form series that trace the evolution of modern species from extinct ancestors. • Downfall to using fossils, hard to find complete set
Comparative Anatomy • Homologous structures – structures shared by related species and have been inherited from a common ancestor • Same structure – different function • Vestigial structures – inherited from ancestors but lost much or all of original function • Hip bones of dolphin
Embryology • Looking at developmental stages of many animals with backbones. • Similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor.
Biochemistry • New science, looking at DNA, RNA and proteins, beyond Darwin’s time. • At the molecular level, the universal genetic code and homologous molecules provide evidence of common descent.