Unit 5-4 Darwin, Natural Selection, & Adaptations

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Darwin, Natural Selection, & Adaptations

Multiple Choice

An organism’s genotype is its

• genetic makeup.

• feather color

• physical appearance.

• stem height.

Multiple Choice

What happens during meiosis?

• Two sex cells combine

• Chromosome pairs separate and are distributed into new sex cells.

• Each sex cell copies itself to form four new chromosomes.

• Chromosome pairs remain together when new sex cells are formed.

Multiple Choice

A purebred chicken with white feathers is crossed with a purebred chicken that has black feathers. Each of their offspring has both black and white feathers. Why does this happen?

• Both alleles for feather color are codominant.

• Both alleles for feather color are corecessive.

• The alleles for feather color are neither dominant nor recessive.

• Several alleles work together to determine the trait.

Lesson Objectives

• Describe some of the experiences that brought Darwin to his theory of Evolution

• Explain how Natural Selection Results in Populations becoming adapted to their environments

• Use Examples to describe different kinds of adaptations found in living organisms

History of Evolution

• For thousands of years, People believed that life on Earth didn't change

• The discovery of fossils helped show that some animals no longer existed, and others seemed to come into being

• Fossil: The preserved remains or traces of a dead organism

  • By looking at fossils, we can see slow and gradual changes in a species over time

Lamarck

• Jean Baptiste Lamark (1744-1829)

  • A French naturalist

    • Naturalist: Someone who studies the Natural world

• One of the first to believe that modern species descended from ancestors that had evolved over time

  • Claimed that organisms gained traits during their lifetimes that they could pass on to their offspring

Charles Darwin

• An English Naturalist

• Traveled around the world on the HMS Beagle and collected samples from multiple continents

  • On his travels, Darwin noticed repeating patterns in all locations regardless of where they were located

What Darwin Observed: Diversity

• Darwin noticed and recorded how much variety there was in living things

  • Different locations had organisms that looked somewhat similar but were vastly different from each other

    • Has similar body shapes, but different sizes, colors, and body parts

• Species: a group of similar organisms that can mate with each other and produce fertile offspring

  • We know of 1.6 million species on Earth

    • Are still discovering more every day

What Darwin Observed: Fossils

• As Darwin traveled he collected fossils

  • Noticed fossils that looked similar to living species, but had differences

    • Differences could be as minor as a difference in one or two bones

    • Differences could be as significant as being much larger in size

Multiple Choice

What are fossils?

• Molds and Casts of Organisms that live today

• drawings of ancient animals and other organisms

• footprints or burrows of small animals that live today

• the preserved remains or traces of organisms that lived in the past

Multiple Choice

A species is a group of similar organisms that

• can mate with each other and produce fertile offspring.

• can live together on an island.

• can migrate to an island from the mainland.

• all have exactly the same traits.

Dropdown

A ​

Select answer

studies the natural world.

The Galápagos Islands

• The Beagle made a stop in the Galápagos islands in the Pacific

  • A chain of Islands located off the coast of South America

    • Are close enough that storms can carry animals from the mainland to the islands

• Contain one of the largest Varieties of Species in the World

Comparing The Galápagos to The Mainland

• Darwin Compared organisms on the island to those on the Mainland

  • Animals on the island resembled those on the mainland but had some differences

• Variation: A difference between members of the same species

• Darwin theorized that the organisms on the island were related to those on the mainland

  • The organisms on the island somehow changed to make them different

​​The Galápogas Iguana

• Has long, skinny Claws and feet for gripping tree branches

• Bright Green Color to blend in with the trees

​​The South Ameican Iguana

• Have short, thick claws and fat feet to reduce friction on slippery rocks

• A darker color to blend in with the beach

Iguanas

Comparing The Islands to Each Other

• Darwin compared organisms on one island to organisms on another island

• Found that similar organisms on different islands still showed a great deal of change

  • One island had tortoises with dome shells, another had tortoises with more flat, saddle-shaped shells

    • People who lived on the islands could recognize where an organism came from just by looking at it

Darwin's Finches

• Darwin studied the different birds that lived on all of the islands

• When he studied them closely, he noticed they were all finches

  • They all had different beak shapes that matched the food available on the island

    • Birds that ate hard seeds had short, thick beaks

    • Birds that had sharp, pointy beaks atethe cacti's skin

• He concluded that the finches all started out the same, but changed as they settled on each island

Adaptations

• Adaptation: a trait that increases an organism's ability to survive and reproduce

  • Anything that gives an organism an advantage in getting food, protecting itself, or finding a mate

Darwin's Hypothesis

• When comparing all his findings, Darwin concluded that organisms change over time

  • Evolution: The process of change over time

• Darwin reasoned that when animals first arrived on the islands, the conditions were different from those on the mainland

  • When he looked at the fossil record, he found that recent fossils most resembled the organisms on the island while older fossils most resembled those on the Mainland

The Theory of Evolution

• The Theory of Evolution

  • Over many generations, Species change to become better adapted to their conditions

• Darwin published his findings in his Book On the Origin of Species in 1859

Multiple Choice

Differences between members of the same species are called

• selections

• variations

• traits

• predators

Multiple Select

Which of the following did Darwin observe on his voyages? (Select all correct answers)

• Variations in organisms

• Fossil Differences

• Similar organisms in different locations

• An organism changing its phenotype

Multiple Choice

An adaptation is a trait that helps an organism survive and

• reproduce

• evolve

• grow

• hide

Multiple Choice

The colors and feet of the two different iguanas are adaptations to their

• Food

• Predators

• Habitat

• Prey

Multiple Choice

_____________ is the gradual change in living things over long periods

• Evolution

• Petrification

• Fossilization

• Paleontology

Multiple Choice

True or false: Darwin made his observations on the Hawaiian Islands

• True

• False

Multiple Choice

Bird beaks having different shapes are an example of a(n)

• Fossils

• Adaptation

• Habitat

• Naturalism

Multiple Choice

Members of a species can mate with each other and produce...

• Gene Pools

• Fertile Offspring

• Variation

• adaptations

Natural Selection

• Darwin proposed that evolution occurs by Natural Selection

• Natural Selection: The process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species

  • Darwin identified several factors that influence the process of natural selection

    • Genetic Variation

    • Overproduction

    • Competition

    • Selection

Natural Selection Factors: Genetic Variation

• Members of a species all have different traits that are inherited through genetics

• Genetic Variation: Any difference in genes between individuals of the same species

Natural Selection Factors: Overproduction

• Most species produce far more offspring than can possibly survive

Natural Selection Factors: Competition

• Since resources are limited, individuals must compete to gain them

  • Does not necessarily involve physical fights

    • A fast organism can avoid a predator better than a slow one

• Fitness: The number of offspring an individual can have over its lifetime

  • The better you are at competition, the more you can reproduce

Natural Selection Factors: Selection

• Some variations make individuals better adapted to their environment

  • Those are the ones that survive, reproduce and pass on their genes to the next generation

• Overtime, Helpful variations build up in a species and unfavorable ones disappear

Example of Natural Selection Australian Rabbits

• In 1859, Rabbits were first introduced to the continent of Australia and quickly became a pest

• In an attempt to control the population, the Australian Government released a myxoma virus into the rabbit population

  • killed 99.9% of rabbits

  • Some rabbits survived the virus and reproduced, and their offspring also resisted the disease

Multiple Select

Select all aspects of Natural Selection

• Variation

• Selection

• Overproduction

• Competition

• Restriction

Dropdown

Without ​

Select answer

All members of a species have the same traits.