Evolution: A Beginning

Evolution: A Beginning Evolution – change over time; modern organisms have descended from ancient organisms Lamarck & Darwin – 2 important scientists for evolution

Lamarck’s Theory of Evolution - 1809 Recognized that living things change over time One of the first scientists to suggest evolution ****By selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in species.****

Lamarck’s Theory of Evolution (continued) Tendency toward perfection All organisms have an innate tendency toward complexity and perfection = change features to help them adapt Ex. Urge to fly = wings

Lamarck’s Theory of Evolution (continued) Use and disuse Organisms alter size and shape of organs by using bodies in new ways Ex. No flying = smaller wings

Lamarck’s Theory of Evolution (continued) Inheritance of acquired traits New traits acquired during lifetime could be inherited Ex. Lift weights to build muscle = children will inherit muscles

Lamarck’s Theory of Evolution

Lamarck’s Theory of Evolution Is Lamarck’s theory legit? Why or why not?

Darwin 1831, traveled around the world on HMS Beagle. During his travels, Darwin made many observations and collected evidence that led him to propose a revolutionary hypothesis about evolution…

Darwin’s Travels

Patterns of Diversity Organisms well suited to environments they inhabited

Living Organisms and Fossils Collected fossils that resembled organisms that were still alive and those that were completely different

Galapagos Islands 1000 km west of South America

Galapagos Islands These islands influenced Darwin greatly Differences in tortoises from island to island due to different environments

Galapagos Islands Tortoises Pinta Tower Pinta Island Intermediate shell Marchena James Fernandina Santa Cruz Isabela Santa Fe Hood Island Saddle-backed shell Floreana Hood Isabela Island Dome-shaped shell

Galapagos Islands Differences in beaks of finches due to different foods eaten Were these animals once members of the same species….?