U3 Case Studies

Question 1

Skin Color Case: Overall Phenomenon

Answer 1

Wherever UV is strong, skin is dark

And wherever UV is weaker, skin is lighter

Question 2

The skin color phenomenon suggests that…

Answer 2

Variation in human skin melanin production arose as different population adapted biologically to different solar conditions

Question 3

Melanin

Answer 3

Pigment in our skin

–> Absorbs and reflects light rays

Question 4

Folate

Answer 4

B Vitamin (needed for healthy embryonic development and sperm production)

Question 5

What does sunlight do to folate?

Answer 5

Breaks it down

Question 6

How does melanin relate to folate?

Answer 6

Melanin protects from UV radiation which in turn protects from folate breakdown

Question 7

Vitamin D Purpose

Answer 7

Calcium absorption

Question 8

What do we need to produce Vitamin D?

Answer 8

UV-B rays

Question 9

Skin Color Case:

High Sun Areas = ________ (and why?)

Answer 9

Dark Skin

–> Provides > protection from folate breakdown while also having enough sun exposure to produce vitamin D

Question 10

Skin Color Case:

Low Sun Areas = ________ (and why?)

Answer 10

Light Skin

–> Provides > absorption of UVB rays to get vitamin D while also providing enough protection from folate breakdown

Question 11

Lactose Intolerance Case

Answer 11

All infant mammals can digest dairy through the lactase enzyme however many stop producing lactase as they age

HOWEVER, certain areas have populations of “lactase persistent” people

Question 12

The lactose intolerance case is due to…

Answer 12

2 separate/distinct mutations that arose INDEPENDENTLY of one another

Question 13

Where did the mutations of lactose intolerance originate from?

Answer 13

Populations in Western Europe and Western Africa evolved INDEPENDENTLY to be lactose intolerant

Question 14

Lactase persistance provided a…

Answer 14

selective advantage (in areas with cattle)

–> (Unlike SE Asia which didn’t have cattle)

Question 15

Elephant Tusks Case: Purpose of tusks

Answer 15

Utilized to:
1) Dig for water
2) Strip bark off trees
3) Males to compete for females

Question 16

Tuskless males are rare because…

Answer 16

Without tusks, in fights for females they can get seriously injured

Question 17

Poaching

Answer 17

Elephants WITH tusks were/are killed for the ivory in their tusks

Question 18

Increase in poaching caused…

Answer 18

a decrease in the male population of elephants with tusks

–> Cause an increase in the population of tuskless elephants

Question 19

Why did tuskless elephants become more populous?

Answer 19

The tuskless elephants were more likely to survive as they were not targeted by poachers

–> Increased their survival which then increased their reproduction

Question 20

Mouse Coloration Case

Answer 20

Darker mice are found in regions with dark lava flows

Lighter mice are found in sandy deserts

Question 21

Benefits of dark fur in a dark environment

Answer 21

Allowed the mice to better blend in with the surroundings: less obvious targets to predators

Question 22

Bird of Paradise

Answer 22

Males:
–> Black with bright turquoise feathers that fluff out to form what looks like a frowny face

Females:
–> Simple brown feathers

(Female chooses mate)

Question 23

Red Capped Manakin

Answer 23

Males:
–> Have a bright red head, black feather body, and practically neon-yellow legs
–> Snap their wings and do a quick dance

Females:
–> Dull olive-green colors which resembles brown

(Female chooses mate)

Question 24

Ibex

Answer 24

(A type of wild mountain goat)

Males: Enormous horns on head
–> Used to fight other males for females

Females: Small horns

(Male-male competition determines mate)

Question 25

Horned Beetle

Answer 25

Males: Have large horns and are overall bigger
–> Used to fight other males for females

Females: Smaller and no horns

(Male-male competition determines mate)

Question 26

Anolis Lizard: Pre-Zygotic Isolation

Answer 26

A lizard species that has a Dewlap (flap of skin below animal’s neck used to attract mates)

–> Changes to this dewlap leads to new species as females wouldn’t recognize different dewlap as being part of their species (not attracted)

Question 27

Orca: Pre-Zygotic Isolation

Answer 27

Orcas are highly intelligent and live in groups (CULTURES)

–> Different orca cultures eat different foods (fish or mammals) and this separates cultures geographically from each other

–> Orca cultures have different dialects to their sounds

Altogether: Prevents different orca cultures from interacting with one another