Evolution the process by which species of living

Evolution: the process by which species of living things change over a period of time.

To scientists, a theory is a coherent explanation for a large number of facts and observations about the natural world.

example n Copernican theory- The sun is in the center of our solar system.

Evolution n The notion that species of living things slowly change as generation succeed is so well validated that it is no longer simply a theory, but a paradigm that shapes every aspect of the science of life.

Charles Darwin n In 1831, Charles Darwin sailed to the Galapagos Islands in the HMS Beagle. Thirty years later he published his theory of evolution, unquestionable one of the most revolutionary ideas science has ever known. Darwin is generally credited with theory of evolution by natural selection.

Five year voyage of H. M. S. Beagle (1831 -1836)

n Darwinian fitness: ability to survive and reproduce in a particular environment

n Break time Darwin found many unique species on his voyage to the Galapagos

Natural selection n Natural selection is that the fittest survive and reproduce and therefore increase the fitness of the species.

n Mutation = Raw material for evolutionary change

The story of the Giraffe

Natural selection n DARWIN'S FOUR POSTULATES of Natural Selection

Natural selection n 1. DARWIN'S FOUR POSTULATES of Natural Selection individuals within species vary

Natural selection n 1. 2. DARWIN'S FOUR POSTULATES of Natural Selection individuals within species vary some of these variations are passed on to offspring

Natural selection n 1. 2. 3. DARWIN'S FOUR POSTULATES of Natural Selection individuals within species vary some of these variations are passed on to offspring more offspring are produced than can survive

Natural selection n 1. 2. 3. 4. DARWIN'S FOUR POSTULATES of Natural Selection individuals within species vary some of these variations are passed on to offspring more offspring are produced than can survive individuals with the most favorable adaptations are more likely to survive and reproduce.

Natural Selection

Natural Selection

The Peppered Moth

The Peppered Moth n The peppered moth is found in England usually lives on lichen-covered trees.

The Peppered Moth n n The peppered moth is found in England usually lives on lichen-covered trees. Before the industrial revolution, there were many more light-colored moths compared to black ones. n They are both the same species, but just different colors.

The Peppered Moth n n The peppered moth is found in England usually lives on lichen-covered trees. Before the industrial revolution, there were many more light-colored moths compared to black ones. n n They are both the same species, but just different colors. Light ones were well camouflaged on the lichencovered trees, whereas the dark ones stand out.

Dark moths on light colored bark are easy targets for hungry birds but are hidden on pollution darkened trees.

Moth n During the industrial revolution, air pollution killed the lichens on the trees, resulting in bare, dark trees. n By the 1950 s, the pepper moths were mostly dark colored.

Moth n In late 1950 s a British physician and amateur moth collector, H. B. D. Kettlewell stated the HYPOTHESIS (just a guess) that the color of the moths protected them from insect-eating birds.

Moth n Before industrial revolution, dark-colored moths stood out against the light trees and were more likely to be eaten by birds, after industrial revolution, the reverse happened.

Basis for Evolution n n Changes very slowly. adaptation: a trait that increases the fitness of an individual.

Basis for Evolution n Changes very slowly. adaptation: a trait that increases the fitness of an individual. While some changes can be observed directly, much what we know about the history of life on earth comes from the fossil record.

Basis for Evolution n n Changes very slowly. adaptation: a trait that increases the fitness of an individual. While some changes can be observed directly, much what we know about the history of life on earth comes from the fossil record. A fossil-is any trace of a long-dead organism.

Law of Superposition n In 1669, Nicolaus Steno proposed the Law of Superposition stating that successive layers of rock or soil were deposited on top of one another by wind or water. This means that the lowest layers are the oldest, while the top layers are the most recent. This law is still accepted today and allows scientists to give fossils a relative age.

Law of Superposition

Geological strata (Layers of rocks) contains an evolutionary sequence of fossils

How we date rocks: Radioactive Dating n n Uranium 238 is a naturally occurring isotope that decays to form lead. It has a half life of 4. 5 billion years. n n n The earth is 4. 5 Billion years old. Decay starts from the moment that uranium is incorporated into rock. So, by measuring the relative proportion of uranium 238 and the lead that has formed we can tell how old a rock or layer of rock is.

Hominid Fossils

GRADUALISM n Living things change very slowly. GRADUALISM

Dino Fossil 206 million years old fossil

Palaeobiology

Maiasaura

All of these samples are evidence of past life

Carcharodon megalodon Tooth

PUNCTUATED EQUILIBRIUM n n Sometimes species will remain the same for a long period of time and then change very quickly. This is usually the result of some catastrophic disaster like an earthquake or volcano.

Dino’s Die because of Meteor impact

Geographic isolation n Geographic isolation prevents a mix of genes with the original species.

Geographic Isolation n n Example: Kodiak Brown Bears This group of bears have evolved into a sub-species, that is different form all other grizzly bears.

An archipelago is a landform which consists of a chain or cluster of islands.

GALAPAGOS FINCHES

THE EVOLUTION OF BEAK SHAPE IN GALAPAGOS FINCHES n n Darwin first thought about evolution while studying in the Galapagos 13 species of finches in the Galapagos islands Islands are barriers that separate each group of the species- “Geographic Isolation” size and shape of the beak has an important consequence for fitness. (What is Fitness? )

Darwin’s finches Medium Tree Finch Cactus Ground Finch Medium Ground Finch Warbler Finch

GALAPAGOS FINCHES n n n Each species has a highly characteristic beak shape. Darwin focused his study on the link between the shape of the beak, the food and the habitat of each species. This research of his was to result in theory of evolution and the 14 finches became "stars" in their own right.

The Case of the Galapagos Finches n n n All species of finch derive from the same original species. The observation: despite their strong resemblance, each species of finch has a highly characteristic beak shape. The evolutionary factors: geographic isolation, ecological environment, food sources, competition.

Adaptive radiation: n many species appear to be related to a single ancestral species.

Divergent Evolution

The Panda's Thumb n n A classic example of evolution. The giant panda is a bear that adapted to eating bamboo.

The panda’s opposable thumb q. Giant pandas have a thumb pad on the hand q. This thumb pad is used by the panda to grasp bamboo shoots q. It uses its thumb to hold and manipulate the bamboo while eating

The Panda has not always had this opposable thumb. Fossil evidence shows that this has evolved over thousands of years.

Comparing bones.

How Do We Know That Evolution Has Occurred? The evidence for evolution has primarily come from four sources: 1. the fossil record of change in earlier species

How Do We Know That Evolution Has Occurred? The evidence for evolution has primarily come from four sources: 1. the fossil record of change in earlier species 2. the chemical and structural similarities of related life forms

How Do We Know That Evolution Has Occurred? The evidence for evolution has primarily come from four sources: 1. the fossil record of change in earlier species 2. the chemical and structural similarities of related life forms 3. the recorded genetic changes in living organisms over many generations

How Do We Know That Evolution Has Occurred? The evidence for evolution has primarily come from four sources: 1. the fossil record of change in earlier species 2. the chemical and structural similarities of related life forms 3. the recorded genetic changes in living organisms over many generations 4. the geographic distribution of related species

Homologous structures n Structures on different organisms are homologous when the have similar base structures but have different functions.

Homologous structures Human Arm Bat Wing Whale Flipper

Analogous Structures n n n Similar functions but NOT structurally related. Insects are arthropods and birds are vertebrates. The wing of a bird and the wing of a butterfly are examples of analogous structures.

Transition fossils