CH. 5 (Engine of Evolution)

Question 1

European Honeybee/Japanese Honeybee vs. Asian giant hornet

Answer 1

european honeybees were DESTROYED (an actual massacre that feeds baby hornets) but the japanese honeybees had adapted to it -> couldn’t really fight it but when a scout hornet finds a nest the native honeybees surround it so it can’t secrete the pheromone that lets other hornets find the nest, vibrate their abdomens to make the temp in the bundle go way up and the hornet dies because temp reaches like 47°C.

Question 2

Parasitic worms vs. ants (their host)

Answer 2

worm turns infected ant red and makes him tip his abdomen up to the sky, birds see the red and think it’s a berry thus eat the infected ant. They pass the eggs in their droppings and ants then scavenge the poo for food for larvae (larvae eat the poo and grow, larvae become pupa, worm produces more eggs in ant’s abdomen)

FRUIT MIMICRY AND PREY MANIPULATION

Question 3

Adaptation by natural selection

Answer 3

1. population must be variable
2. Some proportion of that variation must come from changes in the form of genes (HERITABILITY through genetic difference)
3. The genetic variation must affect the individs. probability of leaving offspring.

Question 4

Natural Selection

Answer 4

the non-random survival of random variants

Question 5

Evolution

Answer 5

change in proportion of alleles in a population

Question 6

There is never a step in evolution…

Answer 6

…that does not create a benefit for an individual

• an adaptation must evolve by increasing reproductive output of its possessor (shouldn’t help an individual survive without ALSO promoting reproduction)
• gene that kills you after reproductive age incurs no evolutionary disadvantage

Question 7

Does evolution increase the fitness of species or individual?

Answer 7

Individual. Sometimes the increase in fitness of an individual benefits the species as a whole but not always. Male lions who displace resident lions of a pride murder all the unweaned cubs then fertilize the females-> gene that promotes infanticide is passed on. It’s not beneficial to the species overall but it DOES allow the genes to be passed on (vs. a nice lion who would just babysit the cubs of other males)

Question 8

Genetic Drift

Answer 8

Random process by which variation in the relative frequency of different genotypes increases or decreases in a small population, owing to chance disappearance of particular genes as individuals die/do not reproduce

Question 9

What is sampling genes like?

Answer 9

A coin toss. You get one copy of each parent gene. If parent is AB then the child gets either A or B. One is lost.

Question 10

What can cause high incidence of genetic diseases in isolated human communities?

Answer 10

Inbreeding which can cause genetic drift which itself can overpower natural selection because there is not enough variation in the gene pool.

Question 11

Why are neutral mutations liable to drift?

Answer 11

Because they do not affect the fitness of the carrier they are liable to be passed on and accumulate (not selected against)

Question 12

Artificial Selection

Answer 12

Natural selection except instead of nature deciding which variants are good and bad, a human selects

Question 13

Examples of artificial selection

Answer 13

• Canis Lupus Familiaris (domestic dog) all descended from one ancestral species of Eurasian grey wolf
• domestication of wild crop plants

Question 14

Richard Lenski

Answer 14

Known for long-term evolution experiment with E. Coli (growing them on citrate—a low glucose medium).

Question 15

Why are bacteria well adapted to evolve?

Answer 15

Short generations and huge populations—perfect conditions for mutations to occur and proliferate.

Question 16

Penicillin vs. Staphylococus aureus

Answer 16

In 1941, penicillin could wipe out every strain of staph infection in the world but now 95% of the strains are resistant (bacterial resistance develops when the variant to survive drug exists in population—the ones who survive have the mutation and pass it on).

Question 17

Which diseases/viruses haven’t developed drug resistance?

Answer 17

polio, measles, streptococus

Question 18

What do populations respond to and subsequently produce adaptive response?

Answer 18

human and natural induced environmental changes. Natural changes include change in salinity, rainfall, temperature, availability of a certain food.

Question 19

What happened to the finches in 1977?

Answer 19

There was a huge drought and the only seeds available during this time were hard. Large-beaked finches prospered.

Question 20

Why is the relationship between an insect and its host plant so intertwined?

Answer 20

They have co evolved. Ex. the plant will have the right feeding apparatus, the bug might have a metabolism that detoxs any plant poison and a reproductive cycle that coincides with plant fruiting.

Question 21

How did the eye evolve?

Answer 21

1. Simple lightspots made of light sensitive pigment (flatworms)
2. Skin folded in forming cup that protected eye spot localizing the light source (limpets)
3. Opening of eye cup narrows sharpening image (chambered nautilus)
4. Clear protective cover over opening (ragworm)
5. Eye fluid coagulated to focus light better—convex shape (abalones)
6. Many species developed muscles to move lens (which can vary the focus)

Evolution of retina and optic nerve follow. Vision would have offered huge evolutionary advantage so it would be selected for.

Question 22

Sea Cucumber

Answer 22

common ancestor of sea cucumber and humans had a gene that was co opted in vertebrates for a new function (protein involved in blood clotting in vertebrates also found in sea cucumber)