8.3 Evolution As An Ongoing Process

Question 1

Coevolution definition

Answer 1

The process in which one species evolves in response to changes in another species

Question 2

Co-evolution example (caribou & wolf)

Answer 2

e.g. caribou evolve to run faster away from wolves; only the quickest wolves will catch enough prey to survive and reproduce

Question 3

Co-evolution example (frog & predators)

Answer 3

e.g. poison-dart frog’s warning coloration adaptation and the avoidance behaviour of its predators

Question 4

Mutualism

Answer 4

a symbiotic relationship wherein both organisms benefit from the interaction

Question 5

How do flowers and insects co-evolve?

Answer 5

-Plants that produce big, bright, fragrant flowers
attract more pollinators
-Pollinators that are attracted to those flowers get
more nectar and are more likely to survive

Question 6

How do plants and herbivorous insects co-evolve?

Answer 6

-Many plants have evolved defence mechanisms in
order to reduce herbivory
-E.g. spines, thorns, toxins
-Natural selection enabled some insects to adapt to
poisons and actually benefit from them, allowing
the insects to also become poisonous to their
predators

Question 7

Mimicry Definition

Answer 7

One species (mimic) evolves to resemble another (model) – may or may not be closely related species

Question 8

List the 2 type of mimicry

Answer 8

batesian and mullerian

Question 9

Batesian mimicry

Answer 9

harmless species evolves to mimic a harmful species

Question 10

Mullerian mimicry

Answer 10

two harmful species mimic each other (additional warning signs)

Question 11

How can complicated structures evolve over time?

Answer 11

through cumulative selection

Question 12

Cumulative selection

Answer 12

the evolution of a simple structure into something more complex through a number of small adaptations

Question 13

Why do some structures stay simple?

Answer 13

“survival of the fittest” – that’s why some organisms still don’t have complex eyes (or any); they don’t need them

Question 14

How can the environment impact structures?

Answer 14

As the environment changes, specialized structures can adapt to new functions

Question 15

Give an example of how specialized structures can adapt to new functions (chitin)

Answer 15

E.g. Chitin is the main component of exoskeletons in arthropods like lobsters
-However, in terrestrial arthropods such as scorpions, the exoskeleton also helps prevent water loss and provides support to the body

Question 16

Give an example of how specialized structures can adapt to new functions (wings)

Answer 16

Natural selection has remodelled penguins’ wings into powerful flippers for swimming and hunting small fish and other prey.

Question 17

How can evolution explain the range of
complexity of eyes in modern organisms?

Answer 17

Cumulative selection explains the range of
complexity of eyes in modern organisms
-it’s the evolution of a simple structure into a
more complex structure through a series of small
adaptations

Question 18

Give an example of evolutionary remodelling
of an existing structure to perform a new
function.

Answer 18

multiple functions of chitin (a main
component of arthropod exoskeletons)

-The exoskeleton of a marine arthropod such as a
reef lobster helps protect the animal from
predators.
-On land, the arthropod exoskeleton of this scorpion fulfills additional functions: resisting water loss and supporting its body on dry land.
-Chemical changes to this material made it even
more watertight as the animals became adapted
to living on land

Question 19

Define co-evolution and provide two examples.

Answer 19

Co-evolution is the process in which one species evolves in response to the evolutionary changes in another species

e.g. the poison-dart frog’s warning-coloration adaptation and the avoidance behaviour of its predators

e.g. milkweed plants produce toxic chemicals and so they are not eaten by most insects. However, the monarch caterpillar has not only managed to develop tolerance to the milkweed’s toxin, but has found a way to store the toxin in its tissues to make itself poisonous to others.

Question 20

Analyze the advantages and disadvantages of
remodelling an existing structure to perform a
new function

Answer 20

in penguins:

advantages: can get away from aquatic predators faster

disadvantages: unbalanced on land, can’t fly, and can’t escape land predators as fast

Question 21

Describe the process that has led to the
following situation. The old-world swallowtail
caterpillar feeds on the fringed rue plant, despite
the toxic oil contained in the plant’s leaves

Answer 21

-the caterpillar didn’t evolve in response to the rue plant’s evolutionary changes, which has made the plant toxic

Question 22

Examine the images of the less aggressive
aardwolf (top) and the aggressive striped
hyena (bottom).
(a) Suggest a reason why some people believe
that the aardwolf is a mimic.

Answer 22

because it resembles the model (hyena) and it mimics it in order to gain survival advantage

Question 23

Examine the images of the less aggressive
aardwolf (top) and the aggressive striped
hyena (bottom).
(b) Are there any disadvantages to the model
(the striped hyena) in having a mimic that is less
aggressive?

Answer 23

the striped hyena’s predators might think that the hyena is less aggressive and will try to kill it

Question 24

(c) The striped hyena does not live in southern
Africa but the aardwolf does. The aardwolf
lives in the same areas in southern Africa as
the brown hyena, which has a blotchy brown
coat. Does this information contradict the
idea that the aardwolf is a mimic? Explain

Answer 24

yes because this hyena is much different from the aardwolf, so it’s not a mimic for this species of hyena because it doesn’t resemble it

Question 25

(d) Propose an alternative explanation for the
similar striped patterns in the two species

Answer 25

if they had to adapt to similar environments, that’s why they might have similar adaptations/features
-e.g. camouflage - both developed stripes

Question 26

Explain how you would provide evidence that
the human hand evolved through cumulative
selection

Answer 26

i would use the first humans’ simple hand structures as evidence of how it evolved and became more complex over time due to a series of small adaptations

Question 27

Some people may assume cumulative selection
makes some species “better” than others.
Explain why this is not accurate

Answer 27

“survival of the fittest” is why some organisms still don’t have complex structures because they don’t need them, simple structures are all they need for their environment