Darwin and Evolution

What happens when specific traits are passed down through many generations?

English Sailed on HMS Beagle 1831 Originally the ship's geologist, eventually also naturalist (studied living things & environments) Darwin's Importance Charles Darwin

Noted for: Observations from South America and Galapagos Islands; compiling these observations into a book called Origin of Species

Differences in Similar Organisms  Darwin observed similar organisms on mainland South America and the Galapagos Islands Examples: Cormorants: on the mainland, these could fly, but the species that lived on the islands was flightless

Examples Iguanas: on mainland they had small claws to climb trees and ate cactus & flowers while island iguanas could swim, had long claws to grip rocks and ate seaweed Tortoises: each island had a species of giant tortoise, but the shape of their shells varied on each island; Darwin could identify which island the tortoises came from just by looking at their shells:)

Darwin wondered: Why were these animals different? Why would they have these obvoisly different characteristics if they were similar organisms?

Adaptations These differences are called adaptations In order to survive in different places, the original organism had to change This change was not a choice, but through genetic diversity

Cormorants: no predators, everything they needed was close to the ground, therefore, they lost the ability to fly Loss of flight is an adaptation.

Darwin's Finches Finches on different islands have different beaks. Why???? Beak type depends on the food available. Finches that are adapted to eat the available food on their island will survive long enough to reproduce. This will pass the trait for the beak that is best suited for survival in that area.

Different Beaks

Natural Selection & the Pepper Moth Natural selection is: the idea that animals that are better adapted for a particular environment will survive, reproduce and pass on these desirable attributes to the next generation

Natural Selection Affected by: overproduction- producing many more offspring than will survive; crabs & fish lay thousands of eggs, but only a few will become adults. What happens to the rest??? competition- "fighting" for available resources (food, shelter, mates). Those that are not successful will die, those that are will reproduce. Do you see a pattern here? Why do organisms want to survive??? variation- differences among individuals in the same species or group. Good variations help an organism survive better and are kept through reproduction. Bad variations that are not helpful are lost, because those organisms do not survive to reproduce and pass on the traits.

Can you Spot the moths?

Predators haveADAPTATIONSthat help them catch their prey Predators have ADAPTATIONS that help them catch their preyADAPTATIONS birds of prey have keen eyesight and sharp beaks and talons venomous snakes have poisonous venom to subdue their prey camouflage allows predators to blend in with their surroundings kingsnakes are immune to the venom of venomous snakes tree frogs have special pads on their feet so they can cling to vertical surfaces

Species have three “choices”: Go extinct in that area. Move to another area (emigrate). Adapt to survive the stress. It works by mutations. If a mutation in an individual helps it to survive, it will survive and reproduce, passing the gene for the mutation on to its offspring. Adaptations- When each organism has a shapes and designs that perform specific functions that help it survive.

Evolution Many generations of natural selection lead to permanent changes in a species. This is called evolution and occurs gradually over time.evolution Different organisms have different rates of evolution, depending on their life spans.

Evolution Evolution is change over time in order to better survive in a particular environment. All organisms evolve- insects, mammals, bacteria, plants and fungi.

Evolution is a theory- which is an idea supported by a large amount of evidence.  Darwin's observations are the beginning of this evidence  Many others have added to his work

Opposition??? Darwin didn't publish his book until 20 years after his voyage This was because he was concerned about how the church would view his theory Although many say evolution is against the teachings of the church, Darwin was a believer in God as well as evolution

Natural Selection Evolution New Species How do new species form??? geographic isolation- when a group of organisms is separated from the rest of its species long enough, it gains new adaptations for survival *** some characteristics will be similar, but usually new adaptations will will make it different enough to be considered a new species

continental drift- when an entire area is isolated, preventing migration or movement of animals; specific & unique features develop as a result *** After Pangea, organisms that started out similar and adapted to survive on these "new continents", forming very specific species on each Example: Australia has kangaroos, echidnas & goannas

How do we know all of this??? Sloths- Darwin found fossil sloths in South America, but they were MUCH larger than the living specimens he saw in the jungles Sharks- aside from being smaller, sharks haven't changed much in the last 100 million years...we know this from fossil evidence:) Fossil records of past creatures & plants...we can examine them and compare them to organisms living today to look for similarities

Homologous structures- structures that serve a similar purpose in organisms that share ancestors Examples:

Natural Selection

Evolution Now?