brittany brown --evolution

Earth’s Change Over TimeEarth’s Change Over Time(Evolution)(Evolution)

Brittany BrownBrittany Brown

Biology 1-5Biology 1-5thth period period

May 1,2007May 1,2007

IntroductionIntroductionIn life there have been different theories as In life there have been different theories as

to how life came about. Many scientists have to how life came about. Many scientists have wonder how Earth continued to change over a wonder how Earth continued to change over a period of time. In Mr. Parr class he has ask his period of time. In Mr. Parr class he has ask his students to present a power point presentation students to present a power point presentation and the Earth Change Over Time or something and the Earth Change Over Time or something related to that topic. These are the following related to that topic. These are the following students in his 5students in his 5thth period class: period class:

Key ConceptsKey Concepts

Earth has been home to living things for Earth has been home to living things for about 3.8 billion years.about 3.8 billion years.

Species change over time.Species change over time.

Many types of evidence support evolution.Many types of evidence support evolution.

Vocabulary Chapter 1Vocabulary Chapter 1

AdaptationAdaptationAncestorAncestorEvolutionEvolutionFossilFossilGeneGeneMass ExtinctionMass Extinction

Vocabulary Chapter 1Vocabulary Chapter 1

Multicellular OrganismMulticellular OrganismNatural SelectionNatural SelectionSpeciationSpeciationUnicellular OrganismUnicellular OrganismVestigial OrganVestigial Organ


Earth has been home to living things Earth has been home to living things for about 3.8 billion years.for about 3.8 billion years.

Earth has been home to living Earth has been home to living things for about 3.8 billion years.things for about 3.8 billion years.

Fossils provide evidence about the history of life Fossils provide evidence about the history of life on Earth. Most fossils are hard body parts or on Earth. Most fossils are hard body parts or bone. Others form when minerals replace the bone. Others form when minerals replace the remains of organisms. Fossils also include prints remains of organisms. Fossils also include prints left by organisms, such as footprints. Very rarely, left by organisms, such as footprints. Very rarely, a fossil is the preserved remains of an organism, a fossil is the preserved remains of an organism, such as a wooly mammoth in ice or an insect such as a wooly mammoth in ice or an insect preserved in sap.preserved in sap.

Earth has been home to living things Earth has been home to living things for about 3.8 billion years. (cont.)for about 3.8 billion years. (cont.)

Relative ageRelative age is how old a rock or is how old a rock or fossil is compared to other rocks fossil is compared to other rocks or fossils. Ancient organisms or fossils. Ancient organisms settled to the bottom of a body of settled to the bottom of a body of water in layers of mud and sand water in layers of mud and sand that later formed rock.that later formed rock.

Absolute ageAbsolute age is the actual age of is the actual age of the rock or fossil. To measure the the rock or fossil. To measure the absolute age of a fossil, scientists absolute age of a fossil, scientists measure its radioactivity. Over measure its radioactivity. Over time, radioactive material time, radioactive material disappears. The older the fossil, disappears. The older the fossil, the less radioactive material it has.the less radioactive material it has.



The The fossil recordfossil record is all of the is all of the information that can be gathered information that can be gathered from the fossils in a particular from the fossils in a particular location. Scientists can then use location. Scientists can then use the record to identify which the record to identify which species lived and died during species lived and died during different periods of time.different periods of time.

Earth has been home to living things for Earth has been home to living things for about 3.8 billion years. (cont.)about 3.8 billion years. (cont.)

Unicellular organisms, made of only Unicellular organisms, made of only one cell, were the first living things one cell, were the first living things on Earth. They appeared about 3.8 on Earth. They appeared about 3.8 billion years ago. The atmosphere billion years ago. The atmosphere then did not have as much oxygen then did not have as much oxygen as it does now. Some of the early as it does now. Some of the early organisms added oxygen to the organisms added oxygen to the atmosphere.atmosphere.


Multicellular organismsMulticellular organisms began to live began to live in Earth's oceans about 1.2 billion in Earth's oceans about 1.2 billion years ago. The fossil record shows years ago. The fossil record shows that the earliest multicellular that the earliest multicellular organisms were tiny seaweeds. The organisms were tiny seaweeds. The earliest animals were similar to earliest animals were similar to jellyfish.jellyfish.


Life appeared on land about 500 million years Life appeared on land about 500 million years ago. Before that, all living things met their needs ago. Before that, all living things met their needs while living in water. Simple plants were the first while living in water. Simple plants were the first land-dwelling organisms, getting water from the land-dwelling organisms, getting water from the soil through roots. The plants in turn provided soil through roots. The plants in turn provided food and shelter to the first fungi and insects on food and shelter to the first fungi and insects on land. After insects, amphibians and reptiles land. After insects, amphibians and reptiles began to live on land, followed by birds and began to live on land, followed by birds and mammals.mammals.


A species becomes extinct when A species becomes extinct when all members of the species have all members of the species have died. Many species have only been died. Many species have only been seen as fossils because they seen as fossils because they became extinct long ago. A mass became extinct long ago. A mass extinction is a period when a large extinction is a period when a large number of species become extinct number of species become extinct in a very short time.in a very short time.


The The Permian ExtinctionPermian Extinction occurred about occurred about 250 million years ago. Approximately 90 250 million years ago. Approximately 90 percent of the species in the ocean, as percent of the species in the ocean, as well as many land-dwelling animals, well as many land-dwelling animals, became extinct. This mass extinction may became extinct. This mass extinction may have been caused by climate change due have been caused by climate change due to all of Earth's landmasses joining to all of Earth's landmasses joining together to form a single, enormous together to form a single, enormous continent.continent.

Example of Cretaceous ExtinctionExample of Cretaceous Extinction


The The Cretaceous ExtinctionCretaceous Extinction occurred occurred about 65 million years ago. More about 65 million years ago. More than half of all the species on Earth, than half of all the species on Earth, including dinosaurs, became including dinosaurs, became extinct. This mass extinction may extinct. This mass extinction may have been caused by a meteorite, a have been caused by a meteorite, a giant space object, colliding with giant space object, colliding with Earth.Earth.


Mass extinctionsMass extinctions are often are often followed by the appearance of a followed by the appearance of a large number of new species. For large number of new species. For example, the extinction of example, the extinction of dinosaurs may have allowed new dinosaurs may have allowed new species of mammals to develop species of mammals to develop and thrive.and thrive.


Species change over time.Species change over time.

Species change over time.Species change over time.Evolution is the process by which species change Evolution is the process by which species change

over time.over time.

In the early 1800s, Jean-In the early 1800s, Jean-Baptiste de Lamarck Baptiste de Lamarck proposed a theory of proposed a theory of evolution. He suggested evolution. He suggested that organisms develop that organisms develop traits during their lives and traits during their lives and then pass them on to then pass them on to offspring. For example, a offspring. For example, a giraffe stretches its neck to giraffe stretches its neck to get high leaves, and then get high leaves, and then passes that longer neck to passes that longer neck to the next generation. But the next generation. But Lamarck could not find Lamarck could not find evidence to support his evidence to support his theory.theory.

Species change over time.Species change over time.Evolution is the process by which species change Evolution is the process by which species change

over time.over time.

Charles Darwin was a Charles Darwin was a naturalist who traveled to the naturalist who traveled to the Galapagos Islands in the late Galapagos Islands in the late 1830s. Darwin's theory of 1830s. Darwin's theory of evolution developed from evolution developed from observing different species of observing different species of tortoises and finches on the tortoises and finches on the Galapagos Islands. For Galapagos Islands. For example, he found some example, he found some finches with beaks useful for finches with beaks useful for cracking seeds and others with cracking seeds and others with beaks useful for capturing beaks useful for capturing insects. Darwin wondered insects. Darwin wondered whether the birds had evolved whether the birds had evolved differently because they were differently because they were in different environments.in different environments.

Species change over timeSpecies change over time..

A group of organisms may evolve due to artificial A group of organisms may evolve due to artificial selectionselection

artificial selectionartificial selection is the process that breeders is the process that breeders use to produce animals with desirable traits. A use to produce animals with desirable traits. A breeder will select individuals with desired breeder will select individuals with desired traits from a group, then allow only those traits from a group, then allow only those individuals to mate. In the next generation, the individuals to mate. In the next generation, the breeder will again select the individuals with breeder will again select the individuals with desired traits and mate them to produce the desired traits and mate them to produce the next generation.next generation.

Species change over timeSpecies change over time..Natural SelectionNatural Selection

Natural selectionNatural selection is the hypothesis Darwin is the hypothesis Darwin developed based on his observations from developed based on his observations from his voyage and from his hobby of breeding his voyage and from his hobby of breeding pigeons. Darwin proposed that members pigeons. Darwin proposed that members of a species that are best suited to their of a species that are best suited to their environment survive and reproduce at a environment survive and reproduce at a higher rate than other members of the higher rate than other members of the species. This process is called natural species. This process is called natural selection.selection.

Species change over time.Species change over time.The process of natural selection depends on a few The process of natural selection depends on a few

key principles.key principles.

OverproductionOverproduction is the is the idea that most idea that most organisms produce organisms produce more offspring than more offspring than can possibly survive. can possibly survive. For example, a For example, a female salmon lays female salmon lays thousands of eggs, thousands of eggs, but only several but only several dozen will survive to dozen will survive to adulthood, and even adulthood, and even fewer will reproduce.fewer will reproduce.

The process of natural selection depends on a few The process of natural selection depends on a few key principles.key principles.

VariationVariation is the natural is the natural differences in traits among differences in traits among the members of a species. the members of a species. Some might have slightly Some might have slightly larger fins, others different larger fins, others different patterns of spots. Mutations patterns of spots. Mutations are changes in genetic are changes in genetic material that cause a material that cause a variation. Variations, due variation. Variations, due either to mutation or the either to mutation or the random combination of random combination of genes from parents, are genes from parents, are passed from one generation passed from one generation to the next.to the next.



An An adaptationadaptation is any is any inherited trait that gives an inherited trait that gives an organism an advantage in organism an advantage in its particular environment. its particular environment. An adaptation is a An adaptation is a variation that makes an variation that makes an individual better able to individual better able to survive than others. For survive than others. For example, a slight change example, a slight change in the shape of a fin might in the shape of a fin might make a fish swim faster make a fish swim faster and avoid predators.and avoid predators.


key principles.key principles. SelectionSelection is the process that is the process that

passes the most successful passes the most successful variations, or adaptations, variations, or adaptations, into the next generation. Of into the next generation. Of the organisms that then the organisms that then survive to reproduce, more survive to reproduce, more and more of them will have and more of them will have the adaptation. The the adaptation. The favorable traits are favorable traits are "selected" for the next "selected" for the next generations. In this way, the generations. In this way, the species as a whole species as a whole becomes more suited to its becomes more suited to its environment.environment.


key principles.key principles. SpeciationSpeciation is the evolution of a new species from is the evolution of a new species from

an existing species. Speciation can occur when an existing species. Speciation can occur when the environment changes. When genetic the environment changes. When genetic changes within two groups of the same species changes within two groups of the same species build up, the two groups may not be able to build up, the two groups may not be able to interbreed anymore. When this happens, two interbreed anymore. When this happens, two different species have formed and speciation different species have formed and speciation has occurred. The diagrams show how three has occurred. The diagrams show how three species of cichlid fish evolved from one original species of cichlid fish evolved from one original species in Lake Tanganyika.species in Lake Tanganyika.



IsolationIsolation is essential to speciation. For a species is essential to speciation. For a species to separate, two groups must be prevented from to separate, two groups must be prevented from reproducing with one another. A geographic reproducing with one another. A geographic boundary, such as a mountain range or ocean, boundary, such as a mountain range or ocean, can result in isolation. The cichlids in Lake can result in isolation. The cichlids in Lake Tanganyika and the finches Darwin observed in Tanganyika and the finches Darwin observed in the Galapagos Islands are examples of isolation the Galapagos Islands are examples of isolation leading to new species.leading to new species.


Many types of evidenceMany types of evidence

support evolution.support evolution.

Many types of evidence support Many types of evidence support evolution.evolution.

A A theorytheory is a widely accepted is a widely accepted statement, based on scientific statement, based on scientific evidence, that helps explain a group of evidence, that helps explain a group of facts. Darwin's theory of evolution is facts. Darwin's theory of evolution is widely accepted because it is widely accepted because it is supported by fossil evidence, biological supported by fossil evidence, biological evidence, and genetic evidence.evidence, and genetic evidence.

Many types of evidenceMany types of evidence support evolution. support evolution.

Evidence from fossils supports evolution. An Evidence from fossils supports evolution. An ancestor is an early form of an organism from ancestor is an early form of an organism from which later forms descend. According to the which later forms descend. According to the theory of evolution, different species should theory of evolution, different species should have common ancestors. Fossil evidence have common ancestors. Fossil evidence supports this idea. For example, modern supports this idea. For example, modern plants and modern algae share plants and modern algae share characteristics with fossil algae that point to a characteristics with fossil algae that point to a common ancestor.common ancestor.


Biological evidence supports Biological evidence supports evolution. Biological evidence evolution. Biological evidence includes the structure of living includes the structure of living things and how living things things and how living things develop into adults.develop into adults.


Vestigial organsVestigial organs are are physical structures that physical structures that were fully developed and were fully developed and functional in an earlier functional in an earlier group of organisms but group of organisms but are reduced and unused are reduced and unused in later species. These in later species. These vestigial organs indicate vestigial organs indicate that the organism had an that the organism had an ancestor that needed the ancestor that needed the trait, and can show how trait, and can show how the modern organism and the modern organism and the ancestor are related.the ancestor are related.


Similar structuresSimilar structures with different functions indicate that with different functions indicate that organisms shared a common ancestor. For example, the organisms shared a common ancestor. For example, the illustrations show that geckos, bats, and manatees have illustrations show that geckos, bats, and manatees have similar bones in their forelimb. A shorter bone leads from similar bones in their forelimb. A shorter bone leads from the shoulder to a joint. From the joint, the longer bone the shoulder to a joint. From the joint, the longer bone leads to a wrist. Because the three organisms live in very leads to a wrist. Because the three organisms live in very different environments, the similar structures have different environments, the similar structures have evolved in very different ways.evolved in very different ways.


Similarities in development of different species that are Similarities in development of different species that are unlike as adults indicate a common ancestor. For unlike as adults indicate a common ancestor. For example, a chicken, a rabbit, and a salamander are example, a chicken, a rabbit, and a salamander are three very different animals. However, their embryos three very different animals. However, their embryos look very similar. As the embryos develop, they become look very similar. As the embryos develop, they become more different. This evidence indicates that many more different. This evidence indicates that many animals must share a common ancestor whose embryo animals must share a common ancestor whose embryo started developing in a similar way.started developing in a similar way.

Many types of evidenceMany types of evidence support evolution support evolution

Genetic evidence Genetic evidence supports the theory of supports the theory of evolution.evolution.

Many types of evidenceMany types of evidence support evolution support evolution

DNA contains the genetic material DNA contains the genetic material found in all cells. It contains a code found in all cells. It contains a code that a cell uses to function properly. that a cell uses to function properly. The code is a pattern of four chemical The code is a pattern of four chemical units called bases, represented by the units called bases, represented by the letters A, T, C, and G.letters A, T, C, and G.


Genes Genes are segments of DNA that relate to a are segments of DNA that relate to a specific trait or function of an organism. For specific trait or function of an organism. For example, the clock gene is found in many example, the clock gene is found in many mammals and relates to how the mammal mammals and relates to how the mammal sleeps and wakes. The clock gene can be used sleeps and wakes. The clock gene can be used to compare different organisms. The more to compare different organisms. The more similar the code is for the clock gene between similar the code is for the clock gene between two organisms, the more closely related the two two organisms, the more closely related the two organisms are.organisms are.

The EndThe End

brittany brown --evolution

Education

living things

earth change

time evolutionevolution

things forearth

hisperiod of time

timeearths change

different periods of

hard body parts oron