Darwin’s Voyages Chapter 5 Section 1 Natural Selection Darwin’s Voyages Chapter 5 Section 1

A Darwin Voyage Evolution Charles Darwin; 22 A change over a period of time Charles Darwin; 22 Voyage on the Beagle 1831 5-year trip around the world Started in England

Living Diversity Diversity Scientists estimate… The variety of living things on earth Scientists estimate… Between 5-50 million living species on earth right now Quite a guess!!!

Fossil Diversity Fossils give us a glimpse into the past Extinction 99.9% of all species that have ever lived are now extinct

Adaptations Physical and behavioral traits Enable organisms to survive Catch food Withstand conditions Reproduce

Fitness The ability of an individual to survive & reproduce To successfully pass on its genes to its offspring

The Galapagos Islands 1000 kilometers west of S. America 600 miles Small & short islands Dry & hot Larger & taller islands More lush

Darwin’s Finches 1 species of finch evolved into many different “specialized” species

Giant Tortoise Shells Tortoises from different islands had different shells Ah, hah!!!! Natural Selection Survival of the fittest Evolution!!!

Vestigial Organs Wings on flightless birds Tailbones on primates

Homologous Structures Develop from similar tissues in the early development stages of the organism

Arguments for an Ancient Earth River Valleys Carved by glaciers over 100,000’s years Shells found in high elevation mountains Plate tectonics!!!

Problems with Reproduction Extinction Birth Rate < Death Rate Over Population Birth Rate > Death Rate Disease Famine War

Peppered Moths Before the industrial revolution, England Trees were light in color from lichen growing on them After the pollution from Ind. Rev. Lichen died, leaving just the dark bark

Helpful Mutations Increases fitness more offspring than others in population Becomes more common in the population

Evolution Any change to the relative frequencies of alleles in the gene pool of a species

Species A group of similar-looking organisms that can breed with one another and produce fertile offspring Bobcat & Lynx

Natural Selection The struggle for existence selects only the fittest individuals to survive in nature Generation after generation

Struggle for Existence Only the fastest rabbits will escape the lynx Only the fastest lynx will catch the rabbits