Week 23: Adaptations

Question 1

What’s an adaptation?

Answer 1

An adaptation refers to a change or adjustment made by an organism, species, or system to better suit its environment or circumstances.

evolution of traits by natural selection

Question 2

How are adaptation produced

Answer 2

Adaptations are well fitted to their function and are produced by natural selection.

Question 3

Adaptation checklist

Answer 3

Heritable
Functional
Increase Fitness
Selected for the purpose (by natural selection).

Question 4

Exaptation:

Answer 4

use of existing traits in new ways, from what it was originally intended for

Unlike adaptations, which are traits that evolve specifically for their current function, exaptations represent the use of existing traits in novel ways.

Question 5

Preadaptation

Answer 5

preadaptation refers to traits that have the potential to be adapted for a new function in the future

Question 6

difference between Exaptation and Preadaptation

Answer 6

preadaptation refers to traits that have the potential to be adapted for a new function in the future,

while

exaptation describes traits that have already been co-opted for a different function than their original purpose.

Question 7

what are Venoms

Answer 7

Venoms are toxic substances produced for the purposes of predation or defense, and are delivered through a bite, sting, etc.

Question 8

Venomous animals and their toxins…

Answer 8

Necrotoxins
Neurotoxins
Myotoxins
Cytotoxins

Question 9

Necrotoxins

Answer 9

Necrotoxins, which cause necrosis (i.e., death) in the cells they encounter.

Question 10

Neurotoxins

Answer 10

Neurotoxins, which primarily affect the nervous systems of animals.

Question 11

Myotoxins

Answer 11

Myotoxins, which damage muscles by binding to a receptor.

Question 12

Cytotoxins

Answer 12

Cytotoxins, which kill individual cells.

Question 13

Aposematism

Answer 13

a form of warning coloration or other visual signals that are used by certain animals to advertise their unpalatability or harmfulness to potential predators

Question 14

Müllerian mimicry

Answer 14

Müllerian mimicry is a form of mimicry in which two or more harmful or unpalatable species resemble each other.

Question 15

question on page 14

Question 16

Batesian mimicry

Answer 16

Batesian mimicry is a form of mimicry in which a harmless or palatable species evolves to resemble a harmful or unpalatable species.

Question 17

But why don’t mimics evolve to have toxins of their own instead?

Answer 17

Adaptations often have tradeoffs.

Time and energy invested in one thing cannot be invested in anything else

Question 18

what happens whenever Rough-Skinned Newts release their toxins

Answer 18

Whenever they release the toxin, they inject themselves with a small amount of TTX, which causes an immune response.

The more TTX, the fewer eggs they lay.

They also release an acrid smell, which warns predators that they are toxic.

Question 19

what are the predators of Rough-Skinned Newts

Answer 19

Common Garter Snakes

Question 20

Review page 26 for tradeoffs between newts and garter snakes

Question 21

Coevolution

Answer 21

Coevolution involves reciprocal adaptations. In other words, both species must exert selection pressure on each other.

Question 22

Plants Constitutive (Physical) deterrents

Answer 22

1) Toughness (fibers, cellulose)
2) Trichomes (hairs)
3) Modified stems, leaves, etc. (spines)
4) Developmentally set; not induced.

Question 23

Plants Chemical deterrents

Answer 23

1) Poisonous compounds
2) Bitter/bad tasting compounds
3) Sticky, oily substances
4) Sometimes induced by herbivory!

Question 24

Prey develop mechanisms to…

Answer 24

Reduce palatibility
Escape detection
Escape from predator

Question 25

how do prey reduce their palatibility

Answer 25

1) Constitutive (spines etc.)
2) Chemical (poisons)
3) Cheat – mimicry! Mimics look like species that are unpalatable, but do not have the chemical compound.

Question 26

how do prey Escape detection

Answer 26

1) Camouflage
2) Unique hiding places

Question 27

how do prey Escape from predator

Answer 27

1) Speed!
2) Play dead
3) Ability to reach unique hiding places

Question 28

How do Predators “Avoid unpalatability” of their prey

Answer 28

1) Behavioral change – e.g flip toxic/spiny prey over!
2) Learn to differentiate mimics

Question 29

How do Predators “Tolerate unpalatability” of their prey

Answer 29

1) Physiological mechanisms to tolerate poisons.

Question 30

How do Predators adapt to “Find / Catch prey!”

Answer 30

1) Improved ability to find prey in the environment: Keen eyes and smell

2) Improved ability to acquire prey: Speed/climbing/burrowing

Question 31

So what’s NOT an adaptation?

Answer 31

Vestigial features: evolutionary leftovers!

By-products – traits that are a side effect of something else.

Exaptations- co-opted traits.

Outdated adaptations – intact traits that used to
be useful but no more!

Results of genetic drift – may in fact be counter- adaptive.

Question 32

example of Exaptation:

Answer 32

The ossicles in synapsids started out as jaw bones.

page 37

Question 33

*Practice question on page 39

Question 34

*Practice question on page 41

Question 35

Practice question on page 43

Question 36

What are Vestigial features:

Answer 36

evolutionary leftovers!

Question 37

what are evolutionary by products

Answer 37

traits that are a side effect of something else.

Question 38

what are Outdated adaptations

Answer 38

intact traits that used to be useful but no more!