No chapter (exam2) Flashcards

Causes of Similarities & Evolution of Adaptations

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1
Q

Causes of Similarities

A

o Homologous Similarity

o Homoplastic Similarities

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2
Q

Homologous Similarity:

A

Resemblance in structure or behavior due to inheritance from a common ancestor

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3
Q

Homoplastic Similarities:

A

Resemblance due to factors other than common ancestry, including

  • -> Parallelism
  • -> Convergence
  • -> Analogy
  • -> Chance Similarity
  • -> Mimicry
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4
Q

Parallelism:

A

Similar characteristics develop separately in independent hereditary lines through each species’ response to similar ecological (environmental) conditions
(Diagram)

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5
Q

Convergence:

A

Similarities in independent hereditary lines through adaption to similar ecological stresses
1. Red Pandas: related to weasels, raccoons, skunks
2. Giant Pandas: a black and white bear
3. Both pandas belong to the order Carnivora, but are bamboo eating vegetarians. Their ancestors separated 43 million years ago, but both have a 6th digit on their for paws derived from the wrist bones that developed due to mutations of the same 2 genes
(Diagram)

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6
Q

Analogy:

A

Characteristics of independent lines that are similar in function, like wings in birds and insects

  1. Homologies: analogies developed from homologous structures
    - Example: bat wings and bird wings
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7
Q

Chance Similarity:

A

Characteristics of independent lines from independent causes that happen to be similar

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8
Q

Mimicry:

A

Similarity in independent lines existing in similar environments

  1. Batesian Mimicry
  2. Mullerian Mimicry
  3. Automimicry
  4. Behavioral Mimicry
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9
Q

Batesian Mimicry:

A

Resemblance of a palatable (eatable) to an unpalatable species
- Example of viceroy butterfly whose pattern imitates monarch (that cannot be eaten)

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10
Q

Mullerian Mimicry:

A

Resemblance between 2 unpalatable species (even grater benefit for both (example of monarch and queen butterfly)

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11
Q

Automimicry

A

“Mimicry” of poisonous members of species by nonpoisonous

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12
Q

Behavioral Mimicry:

A

behavior enhances resemblance to surroundings (as opposed to appearance)
- Examples: insect looking like twig, rabbit looking like rock when it holds still, etc

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13
Q

Evolution of Adaptions

o Adaptationist Approach – Criticisms

A

Gould and Lewontin: Several reasons why existing traits may not be perfect

  1. The trait was once adaptive, but environmental change made it less so
  2. It may be the maladaptive byproduct of another adaptive trait
  3. Gene flow from populations subject to other selection pressures may prevent a local population from evolving a trait better for local conditions
  4. The trait cannot be perfect for one task because the underlying structures are involved in other necessary activities.
  5. The trait evolved based on previous structure, and you can’t start over from scratch
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14
Q

Evolution of Adaption

Adaptationist Approach – Benefits

A
  1. Hypotheses are necessary, and they all have assumptions. Assuming a trait is adaptive is better than assuming it is not adaptive, and thing of all possible reasons why
     2. Traits are not necessarily perfect; but may contribute more to reproductive success than any alternative that has been available
     3. Assuming adaptive value provides a testable hypothesis. If it is not correct, you often produce even more interesting hypotheses.
    - Example of horse gait/speed
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