Changes through time Photos (L to R): 1. African lion attempting to take down a cape buffalo as an example of a predator-prey relationship. The traits of those who survive long enough to reproduce are those past on to the next generation while the traits of those who do not survive are not past on. This is the basis for natural selection – or “survival of the fittest.” 2. A Colorado Potato Beetle. Populations of the potato beetle have become resistant to certain pesticides. This is an example of changes in populations occurring within our lifetime. 3. Fossil of a fish found in the Green River formation near Kemmerer, Wyoming. The fossil record provides much detail on how populations have changed over time.

The Idea Men

Jean Baptiste Larmarck French naturalist and evolutionary theorist 1744-1829 Proposed the inheritance of acquired characteristics First to propose an idea of how life changes over time.

Larmarck’s theory His theory was disproved

Malthus’ Theory Population Growth Malthus proposed the idea that if the human population continued to grow at its same rate, in time there would be a shortage of food and living space. Darwin later applied this concept to plants and animals.

Lyell and Hutton Geologists Proposed that earth is extremely old. Earths surface is constantly changing.

Charles Darwin and Natural Selection (1859) Naturalist on the HMS Beagle

Charles Darwin and Natural Selection (1859) Intrigued by diversity of plants and animals. Collected fossils- Darwin understood that living things only made up part of the natural world

Charles Darwin and Natural Selection (1859) Exploration of South America (3 ½ years) Visited the Galapagos Islands Wrote On the Origin of Species based on his discoveries.

Charles Darwin and Natural Selection (1859) The Galapagos Islands Islands had varying climates and vegetation. Animals on each island were similar but different from animals on mainland South America (Finches and Tortoises) Finches had specialized beaks based on the type of food they ate.

Darwin’s theory of Evolution by Natural Selection -Individuals that are best suited for their environment, will survive and reproduce more than other individuals in the same population.

Darwin’s theory of Evolution by Natural Selection Natural Selection requires:

Darwin’s theory of Evolution by Natural Selection Overproduction/Competition More offspring are produced than can survive Offspring must compete for limited resources. Spider eggs: Many more produced than will survive

Darwin’s theory of Natural Selection Variation (Genetic Variation) Individuals in a population must have traits that differ. These must be inherited traits so they can be passed on to offspring.

Variation in Moths

Darwin’s theory of Natural Selection Some traits make an organism more or less likely to survive. Individuals with a better chance to survive are said to have a higher “fitness” Individuals with a higher fitness leave more offspring.

Darwin’s theory of Natural Selection Adaptation Over time, traits that increase fitness (survival and reproduction) will become more common.

A Simple Example Single Gene Traits Initial Population Generation 10

Darwin’s theory of Natural Selection Summary of Darwin’s Theory Individuals are different, and some variations are inherited Organisms produce more offspring than can survive and many that do survive don’t reproduce Organisms compete for limited resources Individuals best suited for their environment have best chance to survive and reproduce. Others either die off or do not reproduce.

Talking More Specifically About Genetic Variation and Adaptations. Peppered moths

Adaptations Natural Selection causes adaptations to occur. Adaptations are a change in characteristics that helps an organism survive and reproduce. Adaptations can be either behavioral or physical. Behavioral adaptations: ways that organisms act that help them survive and reproduce Mating Dances, Aggression Displays, Playing Dead Physical adaptations: These are adaptations in size, shape, or coloration that help an organism survive and reproduce. Camouflage, Mimicry, Warning Colors, Size, Shape

Darwin’s theory of Natural Selection Darwin suggests that organisms Share common ancestors.

Darwin’s theory of Natural Selection