Table of Contents 7.5 Branching Trees 7.4 Classifying Organisms 7.3 Evolution of Species 7.2 Evidence of Evolution 7.1 Darwin’s Theory Chapter Preview.

Table of Contents

7.5 Branching Trees

7.4 Classifying Organisms

7.3 Evolution of Species

7.2 Evidence of Evolution

7.1 Darwin’s Theory

Chapter Preview

Chapter 7 Preview Questions

1. Compared to body cells, the cells that result from meiosis have

a. half the number of chromosomes.

b. the same number of chromosomes.

c. double the number of chromosomes.

d. triple the number of chromosomes.

Chapter 7 Preview Questions

1. Compared to body cells, the cells that result from meiosis have

a. half the number of chromosomes.

b. the same number of chromosomes.

c. double the number of chromosomes.

d. triple the number of chromosomes.

Chapter 7 Preview Questions

2. Which is true of the alleles for a gene?

a. There are only two alleles for every gene.

b. The alleles are always identical.

c. The alleles are never identical.

d. One allele may be dominant.

Chapter 7 Preview Questions

2. Which is true of the alleles for a gene?

a. There are only two alleles for every gene.

b. The alleles are always identical.

c. The alleles are never identical.

d. One allele may be dominant.

Chapter Preview Questions

3. An organism’s traits are determined by its

a. carbohydrates.

b. DNA.

c. mitochondria.

d. chloroplasts.

Chapter Preview Questions

3. An organism’s traits are determined by its

a. carbohydrates.

b. DNA.

c. mitochondria.

d. chloroplasts.

Chapter 7 Preview Questions

4. Where do sexually reproducing organisms inherit their alleles from?

a. half from each parentb. mostly from their motherc. mostly from their fatherd. only from their mother

Chapter 7 Preview Questions

4. Where do sexually reproducing organisms inherit their alleles from?

a. half from each parentb. mostly from their motherc. mostly from their fatherd. only from their mother

Section 7.1:Darwin’s Theory

What important observations did Darwin make on his voyage?

How did Darwin account for the diversity of species and the differences between similar species?

How does natural selection lead to evolution?

Changes Over Time

CHARLES DARWIN

Darwin’s Voyage

•Charles Darwin sailed on the HMS Beagle --1831•England to the Galápagos Islands.•He was the ships naturalist•5 years

Changes Over Time

Darwin's Discoveries

Finches had beaks adapted to their diet

Mainland Iguanas had short claws

Those on the islands had long claws

The Galapagos cormorant had lost its ability to fly

The shells of the tortoise differed between the islands.

The Theory of Natural Selection

In 1859 ----Darwin proposed his theory of evolution based on the idea of natural selection.

Natural Selection= the strongest or most fit survive

Overproduction and Variation

Overproduction is when an organism produces too many offspring to increase the chance of survival .

Changes Over Time

Overproduction and Variation

Variation is when offspring have differences .

Each individual that is born will have different characteristics.

These characteristics are heritable

Competition and Selection

Variations among animals can give them traits that can help them survive and reproduce.

Changes Over Time

Section 7.2:Evidence of Evolution

What evidence supports the theory of evolution?

How do fossils form?

What do scientists learn from fossils?

Homologous Structures

Homology is when bones are similar in different organisms.

HOMOLOGOUS STRUCTURES

Homologous structures are one piece of evidence scientists use to prove evolution

FOSSILES

ARCHIOPTERIX- the first bird

TRILOBITES

Index fossils that were alive a short time

How Do Fossils Form?

Most fossils form when organisms that die become buried in sediments.

Changes Over Time

The fossils record provides evidence about …

•past live forms

• past environment.

• rate at which evolution occurred

Section 7.3:Evolution of

Species

What factors have contributed to the diversity of species?

How do new species form?

How do scientists infer evolutionary relationships among species?

What causes the extinction of species?

Kaibab and Albert's Squirrels

These two kinds of squirrels have been isolated from one another for a long time.

Isolation may result in two different species.

A Branching Tree

This branching tree shows how scientists now think that raccoons, lesser pandas, giant pandas, and bears are related.

Extinction of Species

Extinction is caused by a change in species' environment.

Section 7.4:Classifying Organisms

Why do biologists organize living things into groups?

What do the levels of classification indicate about the relationship between organisms?

What characteristics are used to classify organisms into domains and kingdoms?

Levels of Classification

As you move down the levels of classification, the number of organisms decreases. The organisms at lower levels share more characteristics with each other.

Three Domains of Life

In the three-domain system of classifications, all known organisms belong to one of three domains–Bacteria, Archaea, or Eukarya.

Protists Fungi Plants Animals

Bacteria Archaea Eukarya

Bacteria

Single celled

No nucleus

prokaryotes

Archaea

Single celled

No nucleus

Prokaryotes

Ancient

Eukarya.

Have a nucleus

Third domain

The kingdoms

Section 5:Branching Trees

How does a branching tree diagram show evolutionary relationships?

A Branching Tree

Branching trees show relationships between groups of organisms.

It also shows the order in which specific characteristics may have evolved.

Shared Derived Characteristics

A branching tree diagram shows evolutionary relationships by grouping organisms according to shared derived characteristics.

ReptilesAmphibians

Egg with shell

Fishes

Four limbs

Backbone

Invertebrates

Ancestor of animals