Unit 5 Evolution

Evolution!!! Change over time….a process in which modern organisms have descended from ancient organisms. Evolution happens to entire populations NOT individuals!

Who’s this guy, DARWIN? Born February 12, 1809. His dad was a poet, philosopher, and naturalist. His mom died when he was 8 years old. At 16, he left his home to study medicine at Edinburgh University.

Who’s this guy, DARWIN? In 1831, he accepted an invitation on a 5 year expedition to South America on the Beagle. During his voyage, he collected specimens which led to his theory on the way life changes over time. He published On the Origin of Species in 1859.

Darwin’s 5-year Voyage

What Did Darwin Find? He found a lot of diversity on different continents. He found and collected many fossils. Most of his studies came off of the Galapagos Islands, which are a group of very diverse islands off the coast of South America.

Galapagos Islands He wondered if animals living on different islands were once members of the same species. Species differed from island to island!!

Who Influenced Darwin’s Thinking? Thomas Malthus 1798 James Hutton 1785 Jean-Baptiste Lamarck 1809 Charles Lyell 1833 Alfred Wallace 1858 ***Now, on your own, make 5 columns on a piece of paper. Read and summarize about each of these scientists in your columns*** (page 374-377)

Most Influential: Lamarck Lamarck’s Evolution Hypotheses Organisms continually change and acquire features to help them live more successfully. Organisms can change the size and shape of their organs by using their bodies differently. Acquired characteristics could be inherited. One of the first scientists to develop a hypothesis on evolution!

On the Origin of Species Not published until 1859. Darwin proposed a mechanism for evolution called natural selection. Many opposed this book!

What is Natural Selection? Traits being selected. Increasing over time, contribute to an organisms fitness in its environment. Cannot be seen! Only observed as changes in a population over many successive generations.

Evolution by Natural Selection Struggle for existence- Members of each species compete to live. Survival of the fittest (adaptations!) Only the strong survive. Descent with modification Each living species has descended with changes from other species over time. A SINGLE “TREE OF LIFE” LINKS ALL LIVING THINGS!

Evidence of Evolution includes Fossil record Geographic distribution of living species Homologous structures Early Development which is composed of which indicates which implies which implies Physical remains of organisms Common ancestral species Similar genes

Geographic Distribution Beaver Muskrat Beaver and Muskrat Coypu Capybara Coypu and Capybara

Homologous Structures Structures that have different mature forms but develop from the same embryonic tissues. Provide evidence that 4 limbed vertebrates descended from common ancestors.

Homologous Structures

Similarities in Embryology

Summary of Darwin’s Theory Individual organisms differ, some of this variation is heritable. Organisms produce more offspring than can survive, many that do survive do not reproduce. Organisms compete for limited resources.

Summary of Darwin’s Theory Natural selection causes species to change over time. Species today are descended with modification from species from the past.