Diversity of Life How are living things alike yet different?

Diversity of LifeHow are living things alike yet different?

Subtitle

Domains, Kingdoms, Classification and Evolution

Objectives

To Keep in Mind: How are organisms classified into Domains and Kingdoms?SC.6.L.15.1How are Evolution and classification Related?SC.6.N.3.1, SC.6.L.15.1, LA.6.2.2.3, LA.6.4.2.2

After this lesson, students will be able to:1. Explain how organisms are classified into domains and kingdoms.2. Explain the relationship between evolution and classification.

ProkaryoteEukaryoteEvolutionBranching tree diagramShared Derived CharacteristicsConvergent Evolution

Vocabulary

Unbeelivable!If you were classifying organisms, would you expect there to be more bees, more birds, or more mammals in the world? The table shows the number of species of bees, mammals, and birds that scientists have found so far!

Why do you think that bee species outnumber mammals and bird species combined?

The bees reproduce feaster and do not need as much food

or space to stay alive.

If it looks like a duck…The first scientist to see the pelt of the platypus thought it was a joke. Could a four-legged, duck-billed, egg-laying mammal exist? How had it evolved? Native people from Australia believed that the first platypus was born when a water rat mated with a duck. But scientists put the platypus into a new group of egg-laying mammals. Then many years later, scientists began to argue. Had the platypus really evolved later with younger marsupials such as kangaroos? Would the platypus have to be reclassified? Scientists studied its DNA and discovered that the platypus was in the right place!

How did DNA help classify the platypus?

The DNA evidence proved that the platypus was a member of a group of very old mammals and that it hadn’t evolved from the same branch as

marsupials.

Three Domains of LifeBacteria and Archaea are unicellular organisms that have no nucleus. Organisms with cells that contain nuclei are called Eukarya.

Domains and Kingdoms

How are Organisms Classified into Domains and Kingdoms?

Taxonomy has come a long way since the time of Linnaeus. Since then, microscopes have helped scientists discover tiny new organisms and identify differences among cells.

How are Organisms Classified into Domains and Kingdoms?

• The modern classification system is made up of three domains. Within the domains are kingdoms.

• Organisms are placed into domains and kingdoms based on their cell type, their ability to make food, and the number of cells in their bodies.

• The three domains are Bacteria, Archaea, and Eukarya.

3 Domains

How are Organisms Classified into Domains and Kingdoms?

Domain Bacteria

• Bacteria are all around you—on the surfaces you touch and even inside your body.

• Some are autotrophs, while others are heterotrophs.

• Members of domain Bacteria are prokaryotes, or organisms whose cells lack a nucleus.

• A nucleus is a dense area in a cell that contains nucleic acids, which are the chemicals that direct all of the cell’s activities.

• In prokaryotes, nucleic acids are not contained within a nucleus.

How are Organisms Classified into Domains and Kingdoms?Domain Archaea

• Like bacteria, members of domain Archaea are also unicellular prokaryotes that can be autotrophs or heterotrophs.

• Archaea are classified in their own domain because their chemical makeup differs from that of bacteria.

• Bacteria and archaea also differ in the structure and chemical makeup of their cells.

• Archaea can be found in extreme environments.

How are Organisms Classified into Domains and Kingdoms?Domain Eukarya

• Domain Eukarya consists of eukaryotes, organisms with cells that contain nuclei.

• Domain Eukarya is divided into four kingdoms: protists, fungi, plants, and animals.

• Organisms in these four kingdoms can be unicellular or multicellular.

• The protist kingdom is sometimes called the “odds and ends” kingdom.

• It includes any eukaryote that cannot be classified as an animal, plant, or fungus.

Kingdoms

How are Organisms Classified into Domains and Kingdoms?

Fungi Kingdom

• Mushrooms, molds, and mildew are all members of the fungi kingdom.

• Most fungi feed by absorbing nutrients from dead or decaying organisms.

How are Organisms Classified into Domains and Kingdoms?

• The plant kingdom includes a great variety of organisms, from giant redwood trees to mosses.

• All plants are autotrophs that make their own food. Members of the animal kingdom are all heterotrophs.

How are Organisms Classified into Domains and Kingdoms?Animal Kingdom

• Members of the animal kingdom are all heterotrophs.

• Animals have different adaptations that allow them to locate food, capture it, eat it, and digest it.

How are Organisms Classified into Domains and Kingdoms?

Us

How are Evolution and Classification Related?• In 1859, Charles Darwin published a theory about how species could change

over time.

• Darwin’s theory is often referred to as the theory of evolution.

• Evolution is the gradual change in a species over time.

• Darwin believed that evolution took place through the process of natural selection in which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species.

How are Evolution and Classification Related?• The theory of evolution has changed how biologists classify organisms.

• Scientists now understand that certain organisms may be similar because they share a common ancestor and an evolutionary history.

• The more similar the two groups are, the more recent the common ancestor probably is.

• Today’s system of classification takes into account the history of a species.

• Species with similar evolutionary histories are classified more closely together.

How are Evolution and Classification Related?• Probable evolutionary relationships among groups of organisms and the

order in which specific characteristics may have evolved are illustrated using a branching tree diagram.

• The base of such a diagram shows the common ancestor.

• Organisms are grouped according to their shared derived characteristics, which are usually homologous structures, or structures that have the same evolutionary origin.

• In addition to comparing the structures of organisms, scientists can also use information about the chemical makeup of their cells.

A Branching TreeThis branching tree diagram shows how cats have evolved.

Evolution and Classification

How are Evolution and Classification Related?• Unrelated organisms may have similar characteristics or body structures

because they evolved in similar environments.

• The process by which unrelated organisms evolve characteristics that are similar is called convergent evolution.

• When studying the chemical makeup of organisms, scientists sometimes discover new information that results in reclassification.

Convergent EvolutionBirds and insects both use wings to fly, but they are not closely related organisms.

Evolution and Classification

Note the characteristics of Figures A, B, C, and D. Which Figure is most like Figure B? If these figures represent fossils of extinct organisms, which would be the ancestor of the others?

Evolution and Classification

Which Kingdom is missing?