Chapter 6: Adaptations over Time

Chapter 6: Adaptations over Time

7th Grade Life Science7th Grade Life Science

I. Ideas About EvolutionI. Ideas About Evolution

A. Early Models of Evolution1. Species: A group of organisms that share

similar characteristics and can reproduce among themselves to produce fertile offspring.a. Many characteristics of a species are inhertited

when they pass from parent to offspring.

2. Evolution: Changes are inherited, characteristics over time.

A. Early Models of Evolution1. Species: A group of organisms that share

similar characteristics and can reproduce among themselves to produce fertile offspring.a. Many characteristics of a species are inhertited

when they pass from parent to offspring.

2. Evolution: Changes are inherited, characteristics over time.

Figure 1Figure 1

By studying fossils scientists have traced the hypothesized evolution of the camel.

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By studying fossils scientists have traced the hypothesized evolution of the camel.

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B. Hypothesis of Acquired Characteristics1. 1809: Jean Baptiste de Lamarck proposed a

hypothesis to explain how species change over time; called the Inheritance of Acquired Characteristics.a. Data showed that traits developed during a parent’s

lifetime, such as large muscles built from hard work or exercise, are NOT passed on to offspring.

b. This evidence did NOT support his hypothesis.

B. Hypothesis of Acquired Characteristics1. 1809: Jean Baptiste de Lamarck proposed a

hypothesis to explain how species change over time; called the Inheritance of Acquired Characteristics.a. Data showed that traits developed during a parent’s

lifetime, such as large muscles built from hard work or exercise, are NOT passed on to offspring.

b. This evidence did NOT support his hypothesis.

C. How Darwin’s Theory Started1. Darwin sailed from England on the HMS Beagle

(ship) to explore the South American Coast. 2. During journey he recorded observations about the plants and

animals he encountered.

a. Darwin hypothesized that some plants and animals on islands off the coast of South America originally came from Central and South America.

b. Darwin observed that species of finches on the islands looked similar to a mainland finch species.

c. Darwin reasoned that members of a population best able to survive and reproduce will pass their traits to the next generation; over time, differences can result in separate species.

C. How Darwin’s Theory Started1. Darwin sailed from England on the HMS Beagle

(ship) to explore the South American Coast. 2. During journey he recorded observations about the plants and

animals he encountered.

a. Darwin hypothesized that some plants and animals on islands off the coast of South America originally came from Central and South America.

b. Darwin observed that species of finches on the islands looked similar to a mainland finch species.

c. Darwin reasoned that members of a population best able to survive and reproduce will pass their traits to the next generation; over time, differences can result in separate species.

D. Darwin’s Observations1. Observed 13 species on the Galapagos Islands

2. All 13 species were similar, except for differences in body size, beak shape, and eating habitats. (See Figure 3 below)

D. Darwin’s Observations1. Observed 13 species on the Galapagos Islands

2. All 13 species were similar, except for differences in body size, beak shape, and eating habitats. (See Figure 3 below)

3. Darwin reasoned that the Galapagos finches must have had to compete for food. a. Finches with beak shapes that allowed them to each

available food survived longer and produced more offspring than finches without those beak shapes.

b. After many generations, these groups became separate species.

3. Darwin reasoned that the Galapagos finches must have had to compete for food. a. Finches with beak shapes that allowed them to each

available food survived longer and produced more offspring than finches without those beak shapes.

b. After many generations, these groups became separate species.

E. Darwin’s Model of Evolution1. Darwin’s Theory of Evolution (Natural Selection)

a. Organisms produce more offspring than can survive.

b. Differences, or variations occur among individuals of a species.

c. Some variations are passed to offspring.

d. Some variations are helpful. Individuals with helpful variations survive and reproduce better than those without these variations.

e. Over time, the offspring of individuals with helpful variations make up more of a population and eventually may become a separate species.

E. Darwin’s Model of Evolution1. Darwin’s Theory of Evolution (Natural Selection)

a. Organisms produce more offspring than can survive.

b. Differences, or variations occur among individuals of a species.

c. Some variations are passed to offspring.

d. Some variations are helpful. Individuals with helpful variations survive and reproduce better than those without these variations.

e. Over time, the offspring of individuals with helpful variations make up more of a population and eventually may become a separate species.

F. Variation1. An inherited trait that makes an individual different

from other members of its species. a. Variations result from permanent changes, or mutations,

in an organism’s genes. i. Example: Variation in human hair line.

b. If variations continue over generations, a new species can evolve.

F. Variation1. An inherited trait that makes an individual different

from other members of its species. a. Variations result from permanent changes, or mutations,

in an organism’s genes. i. Example: Variation in human hair line.

b. If variations continue over generations, a new species can evolve.

2. An adaptation is a variation that makes an organism better suited to its environmenta. Variations that result in an adaptation can involve an

organism’s color, shape, behavior, or chemical make-up.

b. Camouflage is an adaptation. (See figure 4 on next slide)

2. An adaptation is a variation that makes an organism better suited to its environmenta. Variations that result in an adaptation can involve an

organism’s color, shape, behavior, or chemical make-up.

b. Camouflage is an adaptation. (See figure 4 on next slide)

G. Changes in the Source of Genes1. Over time, the genetic makeup of a species migh

change its appearance.a. Example: Finches of Galapagos Island changed.

2. Many environmental factors can bring about changes to a species. a. New species moving into or out of an area can affect

the environment; causing changes in variations of genes.

b. Example: New insects could change the environment; causing other species to change how they find food, what food they eat, or how they live their daily life.

G. Changes in the Source of Genes1. Over time, the genetic makeup of a species migh

change its appearance.a. Example: Finches of Galapagos Island changed.

2. Many environmental factors can bring about changes to a species. a. New species moving into or out of an area can affect

the environment; causing changes in variations of genes.

b. Example: New insects could change the environment; causing other species to change how they find food, what food they eat, or how they live their daily life.

H. Geographic Issues and Variation1. Sometimes mountains, lakes, or other geological

features isolate a small number of individuals from the rest of a population. a. See figure 5 on next slide

b. Some changes affect the isolated population more than the larger population.

c. The two populations can be so different that they no longer can breed with each other!!

H. Geographic Issues and Variation1. Sometimes mountains, lakes, or other geological

features isolate a small number of individuals from the rest of a population. a. See figure 5 on next slide

b. Some changes affect the isolated population more than the larger population.

c. The two populations can be so different that they no longer can breed with each other!!

I. The Speed of Evolution1. Scientists do not agree on how quickly evolution

occurs. a. Some believe it takes thousands of years.

b. Other believe that evolution can occur quickly.

2. Most scientists agree that evidence supports both of these models.

I. The Speed of Evolution1. Scientists do not agree on how quickly evolution

occurs. a. Some believe it takes thousands of years.

b. Other believe that evolution can occur quickly.

2. Most scientists agree that evidence supports both of these models.

J. Gradualism1. Darwin hypothesized that evolution takes place

slowly. a. The model that describes evolution as a slow, ongoing

process by which one species changes to a new species is known as GRADUALISM.

b. According to gradualism, a continuing series of mutations and variations over time will result in a new species. (See figure 1)

J. Gradualism1. Darwin hypothesized that evolution takes place

slowly. a. The model that describes evolution as a slow, ongoing

process by which one species changes to a new species is known as GRADUALISM.

b. According to gradualism, a continuing series of mutations and variations over time will result in a new species. (See figure 1)

K. Punctuated Equilibrium1. Gradualism does not explain the evolution of all

species.

2. Punctuated equilibrium is the rapid evolution when the mutations of a few genes results in the appearance of a new species over a relatively short period of time. (Figure 6 next slide)

K. Punctuated Equilibrium1. Gradualism does not explain the evolution of all

species.

2. Punctuated equilibrium is the rapid evolution when the mutations of a few genes results in the appearance of a new species over a relatively short period of time. (Figure 6 next slide)

L. Punctuated Equilibrium Today1. Can occur over a few thousand or million years,

sometime faster.

2. Penicillin is produced by a fungus Penicillium. a. Example: Some bacteria have evolved to be resistant

to penicillin.

b. Penicillin has been in use since 1943, in 1947 some species of bacteria had already evolved into resistant strains.

L. Punctuated Equilibrium Today1. Can occur over a few thousand or million years,

sometime faster.

2. Penicillin is produced by a fungus Penicillium. a. Example: Some bacteria have evolved to be resistant

to penicillin.

b. Penicillin has been in use since 1943, in 1947 some species of bacteria had already evolved into resistant strains.

3. Bacteria became resistant because people would not take the full dose of the antibiotic.a. The bacteria that survived the unfavorable living

conditions mutated and then reproduced.

b. Now new strains of bacteria are resistant to penicillin.

3. Bacteria became resistant because people would not take the full dose of the antibiotic.a. The bacteria that survived the unfavorable living

conditions mutated and then reproduced.

b. Now new strains of bacteria are resistant to penicillin.