Stations: Darwin's Evidence

Directions: On the next page, you will see multiple "stations" to complete. Please start with Evolution Station One, but from there you can go in any order! Be sure to complete all activities and answer all questions on your sheet!

Evidence for Evolution Stations

Click the eye to return to the directions

Evidence For Evolution Stations

Evolution Station one

Common Ancestry

Fossil Records

START HERE!

Embryological Evidence

homologous & analogous structures

Vestigial Structures

Bonus: blooket

Evolution station one

The theory of evolution is one of the most important concepts in biology.Click the naturalist below who first described evolution by natural selection.

Isaac Newton

Charles Darwin

Albert Einstein

Right! Charles Darwin first described evolution! He noticed that populations of organisms change over time and become better suited to survive and reproduce in their specific environments.

Click on the animal on this slide with the best traits for this environment

In this environment, which organism is "fittest"?

Yes, the grasshopper has the best traits because of its camouflage! Evolution is sometimes summarized with the phrase "survival of the fittest." Living things compete for resources. Those organisms that are more fit to do this will survive and reproduce better than others. These organisms will become more numerous.

Not many people would suggest a shark is "fitter" than the Hulk, but in this case it definitely is! So how does evolution happen? Speciation is the process of one species branching into two. In some cases, differences in ability to get food or to escape from predators can lead to speciation. ​These species usually have similar traits, but can no longer breed.

Which of the following organisms has a body structure most similar to a lion?

Right! Lions and tigers have similar body structures and traits. This leads scientists to consider that they may have a common ancestor. Continue through the stations to learn more!

Be sure you have answered all the questions for the "evolution" section of your notes before moving on!

Common Ancestry

An ancestor is a species from which a modern species evolved. In some ways, this is a probability problem. For example, all mammals have fur and birds always have wings.

Is it more likely that thousands of mammal species evolved furry coats at different times?

Or is it more likely that they all evolved from the same species?

Correct! This species would be a common ancestor of all living mammals with fur. One way to informally organize common ancestors is to use a cladogram.

A cladogram branches off as a species develops new traits. Click on the organism closest related to the fish.

The salamander is the closest related organism! However, one difference is that the salamander has lungs!

Drag and drop the organisms into their placement on the following Cladogram! When you're done, click the arrow to check your answers

Check Your Answers!

Your cladogram on the last page should look like this! For a long time, scientists just used appearance to help group organisms. Now, we have DNA evidence to help us figure out what species are more closely related!

DNA Evidence

Now, DNA is the best piece of evidence we have for common ancestry! We can compare DNA sequences using gel electrophoresis.

Click on the deer species (number) that is most closely related to the common ancestor.

Yes! Deer Species #3 is likely more closely related to the common ancestor, because they have more DNA bands in common. DNA helps us to determine relatedness - the more in common, the more closely related two species are.

Be sure you have completed the section of your notes labeled "Common Ancestry" before continuing to another section!

Fossil Records

We now know that many species adapt from common ancestors.But how do we know what those ancestors looked like? Click on the diagram of the fossil record to continue.

the Fossil record analyzes, dates, and organizes fossils. The fossil record helps paleontologists, archaeologists, and geologists place important events and species in the appropriate geologic era. We can learn about the changes in species over time by analyzing the fossil remains.

below is a link to a gallery of fossil horses. Take a few minutes to check out the differences! when you're ready, click the arrow to move to the next page.

Notice the differences between the species of horses over time! take a look at it's feet- notice it had toes 50 million years ago, and now they have hooves! did you notice the difference in size? click on the modern day horse to move on.

Transitional species are species that are intermediate (a mix) between two different species.

for example, as amphibians evolved from fish, we should see evidence of a transitional species, having traits of both fish and amphibians.

Click on the transitional species in the diagram

Right! That is a tiktaalik! The tiktaalik lived about 375 million years ago. It had fins, scales, and gills- all signs that it was a fish.

However, it also had a flattened body and head- which fish do not have!

Click on its flattened head to learn more!

The tiktaalik also had a neck that seperated its head from its body, digits on its forelimbs, and eyes on the top of its head. It was clear it had features of a land animal.

Using fossil records is just one type of evidence we have of common ancestors. check out the other stations for more types!

Be sure you have filled in all the notes under "Fossil Record" before continuing to the next section!

homologous and anaologous structures

Homologous Structures and Analogous Structures provide evidence for common ancestors. Watch the video below for an introduction about these structures. When you're done, click on the HOMOLOGOUS Structures to the right.

Yes, the forelimbs of various animals in the picture is an example of Homologous Structures!Let's take a more detailed look!

Homologous Structures are organs, limbs, and other structures that look similar in structure, but may have different functions.If you look closely at the picture of the limbs on these animals, you will see some have a completely different function, but have all evolved from a common ancestor. They all have a humerus that leads to a radius and ulna, which leads to the carpals and metacarpals and finally phalanges. Click on the Whale's phalanges (fingers) to move to the next page.

Analogous structures are the opposite. They have different structures, but serve the same function. Take a look at the examples to the right.These do not provide evidence because the structures formed independently to serve the same purpose without a common ancestor.

Click on one of the analogous structures that help an organism fly to practice analyzing these structures!

Drag the following pictures to the correct type of structure.Click the arrow to move on when you're done!

ANALOGOUS STRUCTURES

HOMOLOGOUS STRUCTURES

Human and turtle heart

A platypus and duck both lay eggs

Dorsal fin of a dolphin and shark

Ankle bone of a pig and deer

Giraffes and humans both have 7 vertebrae in our necks!Which type of structures does this give evidence for?

HOMOLOGOUS STRUCTURES

ANALOGOUS STRUCTURES

That's right! Giraffes and humans have similar structure of vertebrae provides evidence for homologous structures. This suggests we have a common ancestor!

Nice work! Be sure you have filled in all the notes under the "homologous structures" section before moving on to the next part.

Vestigial Structures

As organisms evolve, there are often remaining structures that haven't fully disappeared. But they have lost most or all of their original purpose.

Do you have one?! Try it out! Put your pinky and thumb together as shown. Does your tendon stick out?

YES

NO

80-85% of people do have this tendon, though, because if a structure isn't negatively affecting the organism, it most likely won't disappear entirely!

About 10-15% of people don't have this tendon!This tendon has no effect on grip strength or really anything else. It is completely useless!

It does, however, provide evidence that they may share common ancestry with other organisms that do use that body part, organ, or structure!

Dog's Dew Claw

Click the buttons on the rainbow to check out multiple vestigial structures.When you're done, click the arrow below!

Goosebumps

Appendix

Wisdom Teeth

Ear Rotation Muscles

Dog's Dewclaw

The dewclaw is present on many animals.It's something that has evolved into a thumb in others. Ancient ancestors to the dog once used this structure to climb trees, but as dogs evolved to run on the ground and stand more on their digits than their whole foot, their dewclaw became mostly useless.

Goosebumps

What's the point of these?Most animals that have fur can lift these muscles up to stand up their fur. This allows more air to be trapped in their fur for insulation and keeping warm. Goosebumps also happen when an animal gets scared or feels threatened to make its hair stand up.

How about for people though?Useless! We have so many little hair on our bodies that goosebumps do nothing to keep us warm.

Appendix

Humans have an appendix which many believe serves as a housing for good bacteria in our intestines, so it may actually serve a purpose for us- but it is believed that the original pupose of the appendix may have changed. The appendix helps many other animals in digesting cullulose-rich diets, such as grass.

Wisdom Teeth

Some humans have wisdom teeth. They hardly fit into most of our skulls nowadays, which is why some people have to have them removed!Human skulls have changed over milions of years. They used to be longer, allowing more room for teeth in the jaw. Once humans could cut foods, cook foods softer, and use agriculture, our need for stronger jaws decreased.

Now one in four people are missing at least one wisdom tooth.It wouldn't be surprising if no one had any wisdom teeth another million years from now!

Some animals have the ability to rotate their ear 90 degrees or more to help them locate the direction of sounds and hear better.Studies show that our brains subconsciously tell our ears to turn towards sounds, too, even though they no longer rotate!

Ear Rotation Muscles

Can you move your ears? If so, probably just slightly.We still have ear rotation muscles, but they are have lost their original function.

Vestigial Structures

Now that you've learned about a few examples, answer the following question! Which of the circles describes a vestigial structure?

A whale's leg bones

A bird's beak

Human's fingers

A cat's tail

Great job! A whale's leg bones are vestigial structures that suggest that they have a common ancestor that once lived on land. The species adapted and gradually lost their legs, but retained the vestigial bones.

Congrats! You've completed the station! Be sure you have filled in all the notes under "Vestigial Structures" before moving on to the next topic!

Embryological Evidence

Embryology is the study of the development of embryos (an organism before it's born or hatched) across different species. Scientists have found that organisms with a common ancestor have similar traits during early embryological development.

Click the embryos above to see more examples

Chick

How similar are they? Try to pin each organism's name under its early embryo

Fish

Human

Hog

Calf

Rabbit

Salamander

Tortoise

Click Here When You're Done!

Chick

How about now? Try to pin each organism's name under its late stage embryo

Fish

Human

Hog

Calf

Rabbit

Salamander

Tortoise

Click Here When You're Done!

Click on the embryos that were HARDER to label!

Yes! It was very difficult to tell the early embryos apart! That's because of how similar the traits are in all of these organisms! All vertebrate embryos essentially have the same parts to start.

However, as they continue to grow, they change drastically due to their adaptations that help them survive in their environment. Click the early human embryo to move on

All vertebrate embryos also have what looks like "gill slits," but are not actually gills. These structures in embryos are called pharyngeal arches. These are exposed (visible outside) early in embryo development but eventually they close in many species.​

Click the arrow to find out what the pharyngeal arches become.

Only in fish and in larval amphibians do pharyngeal arches develop into gills.​ In mammals, the tissue within the first two gill slits forms part of the lower jaw and the bones of the inner ear.

This is the end of this section! Be sure you have filled in all parts of the notes under "Embryological Evidence" before continuing on.

Bonus: Blooket

If you are on this page, this means that you have completed EVERY OTHER SECTION already! If that is the case, feel free to practice our topic using the Blooket link in the icon below, or work on missing work!