Week 23 Flashcards
Define the term adaptation
An adaptation is a feature that is common in a population because it improves the function of the organism. These traits are produced by natural selection and are well-fitted to their function.
List and define the criteria required for a trait to be considered adaptive
For a trait to be considered adaptive, it must meet the following criteria:
Heritable: The trait must be passed down genetically.
Functional: The trait must serve a purpose.
Increase Fitness: The trait must improve the organism’s ability to survive and reproduce.
Selected for the purpose by natural selection.
Differentiate between true adaptations and categories of traits that are not true adaptations
True adaptations meet all four of the following criteria:
Heritable – The trait must be genetically passed down.
Functional – The trait must serve a purpose.
Increase Fitness – The trait must provide a survival or reproductive advantage.
Selected for the purpose by natural selection – The trait must have evolved specifically due to its function.
Not true adaptations include:
Vestigial features: Evolutionary leftovers (e.g., dewclaws).
By-products: Traits that exist as side effects of another adaptation.
Exaptations: Traits that originally evolved for one function but are now used for another (e.g., jaw bones evolving into ear ossicles).
Outdated adaptations: Traits that were once beneficial but are no longer useful.
Results of genetic drift: Traits that persist due to chance rather than selection and may be counter-adaptive.
Define, identify, and provide examples for 2 types of mimicry
Müllerian mimicry: Two or more well-defended species that share common predators mimic each other’s warning signals to their mutual benefit.
Example: Multiple toxic species developing similar warning coloration.
Batesian mimicry: A harmless species mimics the appearance of a harmful or noxious species without possessing any defenses itself.
Example: A palatable species resembling a toxic one to avoid predation.
Discuss several examples of adaptations, and identify trade-offs that organisms exhibit in their adaptations
Rough-skinned newts produce a potent neurotoxin (TTX) to deter predators, but producing more TTX reduces the number of eggs they can lay. They also release an acrid smell to warn predators.
**Common garter snakes **have evolved resistance to TTX, but this adaptation comes with trade-offs: reduced crawling speed and impaired thermoregulation, making them more vulnerable to other predators.
Predator-prey arms races: Organisms continuously evolve adaptations to counteract each other (e.g., prey develop toxins, and predators evolve resistance).
Provide examples of traits that are not adaptive, and categorize them
Vestigial features: Dewclaws.
By-products: Traits that exist as a side effect of something else.
Exaptations: The ossicles in synapsids started out as jaw bones but evolved into parts of the mammalian ear.
Outdated adaptations: Evolutionary anachronisms—traits that were useful in the past but no longer serve a function today.
Exaptation
A trait that originates to perform one function, that is then co-opted (taken and changed) for a different function.
preadaptation
refers to the possibility of a characteristic to adopt a new biological
function with little to no evolutionary modification.
Are venoms an adaptation ?
yes
Why dont 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 is 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 counteradaptive.
