Week 23: Adaptations Flashcards
What’s an adaptation?
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
How are adaptation produced
Adaptations are well fitted to their function and are produced by natural selection.
Adaptation checklist
Heritable
Functional
Increase Fitness
Selected for the purpose (by natural selection).
Exaptation:
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.
Preadaptation
preadaptation refers to traits that have the potential to be adapted for a new function in the future
difference between Exaptation and Preadaptation
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.
what are Venoms
Venoms are toxic substances produced for the purposes of predation or defense, and are delivered through a bite, sting, etc.
Venomous animals and their toxins…
Necrotoxins
Neurotoxins
Myotoxins
Cytotoxins
Necrotoxins
Necrotoxins, which cause necrosis (i.e., death) in the cells they encounter.
Neurotoxins
Neurotoxins, which primarily affect the nervous systems of animals.
Myotoxins
Myotoxins, which damage muscles by binding to a receptor.
Cytotoxins
Cytotoxins, which kill individual cells.
Aposematism
a form of warning coloration or other visual signals that are used by certain animals to advertise their unpalatability or harmfulness to potential predators
Müllerian mimicry
Müllerian mimicry is a form of mimicry in which two or more harmful or unpalatable species resemble each other.
question on page 14
Batesian mimicry
Batesian mimicry is a form of mimicry in which a harmless or palatable species evolves to resemble a harmful or unpalatable species.
But why don’t mimics evolve to have toxins of their own instead?
Adaptations often have tradeoffs.
Time and energy invested in one thing cannot be invested in anything else
what happens whenever Rough-Skinned Newts release their toxins
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.
what are the predators of Rough-Skinned Newts
Common Garter Snakes
Review page 26 for tradeoffs between newts and garter snakes
Coevolution
Coevolution involves reciprocal adaptations. In other words, both species must exert selection pressure on each other.
Plants Constitutive (Physical) deterrents
1) Toughness (fibers, cellulose)
2) Trichomes (hairs)
3) Modified stems, leaves, etc. (spines)
4) Developmentally set; not induced.
Plants Chemical deterrents
1) Poisonous compounds
2) Bitter/bad tasting compounds
3) Sticky, oily substances
4) Sometimes induced by herbivory!
Prey develop mechanisms to…
Reduce palatibility
Escape detection
Escape from predator
how do prey reduce their palatibility
1) Constitutive (spines etc.)
2) Chemical (poisons)
3) Cheat – mimicry! Mimics look like species that are unpalatable, but do not have the chemical compound.
how do prey Escape detection
1) Camouflage
2) Unique hiding places
how do prey Escape from predator
1) Speed!
2) Play dead
3) Ability to reach unique hiding places
How do Predators “Avoid unpalatability” of their prey
1) Behavioral change – e.g flip toxic/spiny prey over!
2) Learn to differentiate mimics
How do Predators “Tolerate unpalatability” of their prey
1) Physiological mechanisms to tolerate poisons.
How do Predators adapt to “Find / Catch prey!”
1) Improved ability to find prey in the environment: Keen eyes and smell
2) Improved ability to acquire prey: Speed/climbing/burrowing
So what’s NOT an adaptation?
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.
example of Exaptation:
The ossicles in synapsids started out as jaw bones.
page 37
*Practice question on page 39
*Practice question on page 41
Practice question on page 43
What are Vestigial features:
evolutionary leftovers!
what are evolutionary by products
traits that are a side effect of something else.
what are Outdated adaptations
intact traits that used to be useful but no more!
