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BIOL 112 > Chapter 18 > Flashcards

Chapter 18 Flashcards

1
Q

Darwin’s postulates:

A
  • Most characteristics are heritable, passed from parent to offspring.
  • More offspring are produced than can survive; there’s competition for resources. 
  •  Characteristics of offspring vary, and these variations are heritable.
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2
Q

Definition of Evolution

A

“Descent with modification”

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3
Q

What did Darwin first observe in regards to evolution?

A

He noticed different shaped beaks in finch species. He speculated that beaks from ancestral species adapted over time with the change in different food sources.

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4
Q

T/F: Organisms evolve during their lifetimes.

A

FALSE: Natural selection acts on individuals, only populations evolve

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5
Q

Microevolution

A

Change in allele frequencies in a population over generations

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6
Q

Three mechanisms that cause allele frequency change:

A

1) Natural Selection
2) Genetic drift (randomness)
3) Gene flow (migration)

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7
Q

Microevolution Vs. Macroevolution

A

Microevolution happens on a small scale (within a single population), while macroevolution happens on a scale that transcends the boundaries of a single species.

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8
Q

Macroevolution

A

major evolutionary change. The term applies mainly to the evolution of whole taxonomic groups over long periods of time, rather than just one species

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9
Q

The 2 types of Macroevolution

A

(1) Divergent Evolution and (2) Convergent Evolution

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10
Q

Divergent Evolution

A

When two different species share a common ancestor, but have different characteristics from each other

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11
Q

Convergent Evolution

A

When two different specifies do not share a common ancestor from each other but have similar characteristics through adaptation through environmental conditions

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12
Q

Example of Artificial Selection

A

GMO’s

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13
Q

Individuals ______ , species ______ .

A

Individuals adapt, species evolve.

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14
Q

Homologous Structures

A

Same internal structure but different outside structure that indicates those organisms share a common ancestor

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15
Q

How is camouflage an example of convergent evolution?

A

Camouflage is not caused by common ancestry, but rather similar selection pressures (ex. Polar bears, snow foxes, snowy owls, etc. aren’t related but have all had similar phenotypes evolve due to the same evolutionary pressures)

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16
Q

Example of Biogeography

A

Fossils in one location matching fossils in a completely different location

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17
Q

T/F: Nature is teleological

A

FALSE: Nature is not teleological! (It has no plan, purpose, or motive)

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18
Q

Species

A

A group of organisms that can interbreed and produce viable, fertile offspring

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19
Q

Hybrid

A

A cross between two species

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20
Q

Gene pool

A

A collection of all the variants of genes in a species

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21
Q

Biological Species Concept

A

A species can interbreed.
A species does interbreed.
A species produced viable offspring.
The species does NOT interbreed with other “groups”.

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22
Q

Two types of Speciation:

A

Allopatric Speciation and Sympatric Speciation

23
Q

Allopatric Speciation Vs. Sympatric Speciation

A

Allopatric involves geographic isolation while Sympatric occurs in the same geographical area

24
Q

Reproductive Isolation

A

The existence of biological factors (barriers) that impede two species from producing viable, fertile offspring

25
Q

Reproductive isolation can be classified as either one of two things?

A

Prezygotic barriers and Postzygotic barriers

26
Q

Examples of Prezygotic barriers

A

Habitat, Temporal, Behavioral, Mechanical, or Gametic isolation

27
Q

Examples of Postzygotic barriers

A

Reduced hybrid viability, reduced hybrid fertility, or hybrid breakdown

28
Q

Prezygotic barriers block fertilization from occurring by:

A

Impeding different species from attempting to mate, preventing successful completion of mating, hindering fertilization if mating is successful

29
Q

Habitat Isolation

A

Two species rarely interact (breed) due to their habitat (ex. Water snake and desert snake)

30
Q

Temporal Isolation

A

Two organisms are reproductively viable at different times of the year

31
Q

Behavioral Isolation

A

Courtship rituals and other behaviors unique to a species are effective barriers to mating

32
Q

Mechanical isolation

A

Morphological differences can prevent successful completion of mating (a hermit crab and a snail can’t breed bc of their shells for example)

33
Q

Gametic Isolation

A

Sperm of one species may not be able to fertilize eggs of another species

34
Q

How does Gametic isolation work?

A

Proteins on the sperm head called “Bindin” proteins are species specific and have to hit specific receptors on the covering of the egg (the sperm can only fertilize certain types of eggs)

35
Q

Post-zygotes barriers prevent the zygote from developing into a viable, fertile adult EVEN THOUGH….

A

In all three types of post zygotes barriers, there IS fertilization and there IS a gestation and an organism IS born!! They are just existent for short periods of time

36
Q

Why are islands a great representation of Allopatric speciation?

A

Islands are great to study the same species and observe how they differ from island to island due to their isolation from one another (ex. Galápagos Islands!!)

37
Q

The greater the barriers subdivide a region, the greater the ….

A

… degree to which speciation will occur (ex. A canyon might create a barrier for small rodents but not for birds, coyotes, or pollen)

38
Q

Seperate populations may evolve independently through:

A

Mutation, natural selection, and genetic drift

39
Q

Sympatric speciation can occur if gene flow is _____ by these three factors:

A

Reduced; Polyploidy, Sexual selection, habitat differentiation

40
Q

Polyploidy

A

The presence of extra sets of chromosomes due to accidents during cell division (aka mutations! Different number of chromosomes = different species!)

41
Q

T/F: Polyploidy is much more common in plants than in animals

A

TRUE: Polyploidy can produce new biological species within a SINGLE generation

42
Q

Autopolyploid

A

An individual with more than two chromosome sets, derived from a single species

43
Q

An allopolyploid is a species with multiple sets of chromosomes derived from _____

A

Different species

44
Q

Speciation can occur when….

A

1) groups become isolated geographically for long periods of time
2) Changed (mutations) in each group over time lead to the groups no longer being reproductively compatible

45
Q

Vicariance

A

When a natural situation (barrier) arises to physically divide organisms

46
Q

Aneuploidy occurs when…

A

… gametes have too many or too few chromosomes due to nondisjunction during meiosis (the chromosomes don’t split evenly between the two daughter cells)

47
Q

Autopolyploidy occurs when …..

A

… mitosis is not followed by cytokinesis

48
Q

Alloploidy occurs when….

A

… two species mate to produce viable offspring

49
Q

Allo & Sympatric = ?
Pre & Postzygotic = ?

A

a) how species came to be
b) how they are maintained

50
Q

In gradual speciation, species diverge….

A

at a slow, steady pace as traits change incrementally

51
Q

In punctuated equilibrium, species diverge ….

A

… quickly and then remain unchanged for long periods of time

52
Q

Vestgial Structures

A

Structures that have a diminished functionality over time (features in modern animals that are no longer in use)

53
Q

Analogous Structures

A

Structures that have similar functions but with dissimilar evolutionary origins

BIOL 112 (14 decks)

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