Adaptations, Natural Selection, and Evolutionary

Theory

What is an adaptation? Take out learning objectives and find “adaptations” under LO #5

– Before we talk about evolution, must talk about adaptations… Adaptation: An inherited characteristic that increases an organism’s

chance for survival.– Individuals do NOT develop genetic adaptations in their lifetime– Adaptations develop through small changes in DNA over time

(when do changes in DNA occur?) Do all organisms in a population (one species) have identical

adaptations? Discuss. Nope! Adaptations vary in a population

– Some individuals have better genetic adaptations than others– These adaptations are due to…?

Differences in DNA What is an example of a human adaptation that is better in some

individuals than others? Discuss. Here are some other cool (non-human) adaptations

– Record at least three in your notes

“Evodots”In this “species” some individuals happen to be faster (red, orange, yellow) and some happen to be slower (black, purple, blue).

Faster speed allows dots to better avoid predators.

Speed is an adaptation

Faster dots

Slower dots

Camel Fat in humps helps

animal survive long periods without food - metabolized fat produces water as a byproduct.

Camels that happen to have DNA that builds larger humps (fat reserves) – more likely to survive during droughts.

Fat storage is an adaptation

Monarch Butterfly

                                              

 

Viceroy Butterfly

Monarch butterflies taste bad to many predatory birds.Viceroy butterflies taste fine, but look like monarchs –often avoided by predators.

Viceroys that have DNA that causes them tolook more like monarchs - better adapted and less likely to get eaten. Coloration is an adaptation.

The “lure” in many anglerfish - adaptation that helps attract prey.

Anglerfish with DNA that builds a better lure - more likely to captureand eat more prey. This helps them survive and reproduce.

The lure is an adaptation.

Puffer fishPuffer fish have an ability to "puff" up with air or water - look like a bigger fish if they get angry or feel threatened.

Puffer fish that scare off more predators are more likely to survive and reproduce.

“Puffing” is an adaptation caused by DNA.

How do adaptations become more common in a population?

How does the frequency of an adaptation change in a population?

In your binder, develop a scientific hypothesis that answers the question above. – Be ready to share. Be specific about the “because”.– Start with, “If some organisms are born with slightly

better adaptations than other individuals in the species, then the adaptation will become…because…

Possible answer: “If some organisms are born with slightly better adaptations to their environment than other individuals in the species, then the adaptation will become more common because it will help those organisms survive, reproduce, and pass down the DNA that is responsible for their adaptations.

How do adaptations develop in the first place?

How do adaptations develop in the first place? Write down your best answer, be ready to share.

Adaptations develop because of “good” mutations in DNA - lead to slightly improved traits.

This is a slow, slow, slow process Mutations result in small changes that accumulate over time

– Example of ONE mutation changing a whole population - animation

Small changes can sometimes lead to significant adaptations over a long time

More on all this later…

Evolutionary Theory

A scientific theory that describes:

1) How “natural selection” has caused changes and improved adaptations in organisms over time by allowing the “fittest” to survive and reproduce.

(we’ll cover “natural selection” in more detail tomorrow…)

2) How modern organisms have descended from ancient organisms.

Review – no notes! What is an adaptation? Why are there differences in

adaptations in the same species? What is responsible for these differences in a species?

How do adaptations become more common in a species?

Questions? Questions? Review your notes alone for one

minute. I’ll take questions about notes or related topics…or, if no questions, we’ll discuss yesterday’s activity

How are parts of yesterday’s activity realistic while other parts are not realistic? Discuss, be ready to share.

Venus Fly Trap

Coral Snake Milk Snake

GiraffesTheir very long necks are an adaptation to feeding at high levels in the treetops. The neck veins contain valves and a network of tiny veins (rete mirabile) that help prevent blackouts when the animal lowers its head to drink. Giraffes with longer necks have survived and reproduced better than those with shorter necks.

Flying Squirrel

                                          

                        

By gliding through the air among the trees, they avoid ground predators

Arctic FoxDuring summer months, the Arctic fox has a brown coat. During winter, the coat of the Arctic fox is white, matching its icy, snowy surroundings.

Foxes that blend better can avoid more predators, sneak up on more prey, and therefore better survive to reproduce.

Walking Stick

Walking sticks are insects that have evolved an adaptation that helps them blend in with twigs and sticks.

Those walking sticks that blend in better are able to avoid more predators.

Bombardier Beetle The precursor chemicals

have to be stored separately in the beetle's abdomen because they combine explosively when brought together. ejected at high speed and at such a high temperature (100 C).

the end of its abdomen rotates 270 degrees in any direction, which allows for an impressive "firing range."