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Biology > Evolution of Populations > Flashcards

Evolution of Populations Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Evolution occurs in _______ NOT _________

A

Evolution occurs in populations NOT individuals

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2
Q

Genetic basis of evolution

Biological species

A

group of similar individuals who mate + produce viable fertile offspring

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3
Q

Geographic variation

A

change in the genetic composition of separate populations

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4
Q

Population

A

group of individuals of the same species living in the same geographical area

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5
Q

Individuals of a population generally have the same number + type of genes
what’s different?

A

Some variation due to environment, some due to heredity

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6
Q

Population genetics

A

science that studies the process of microevolution

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7
Q

Microevolution

A

Exchange in the genetic makeup of a population from generation to generation

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8
Q

Gene pool

A

All copies of every type of allele at every locus in all members of the population

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9
Q

Allelic frequency

A

The % of alleles in a gene pool

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10
Q

The Hardy-Weinberg Principle:

Compare the scenario with data from a real population

A
  • If there are no differences → real population is not evolving
  • If there are differences → suggests real population may be evolving
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10
Q

Genotype frequency

A

the proportion of a particular genotype in the population

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11
Q

The Hardy-Weinberg Principle

A
  • One way to assess if natural selection or other factors are causing evolution at a particular locus
  • Determine what the genetic makeup of a population would be if it were not evolving at that locus
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12
Q

If allele frequency changes over generations → __________

A

If allele frequency changes over generations → evolution is occurring

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13
Q

Factors causing microevolution

(5)

A
  1. Mutations (random mechanism)
  2. Sexual recombination (random mechanism)
  3. Natural selection (adaptive, non-random)
  4. Genetic drift (random mechanism)
  5. Gene flow (random mechanism)
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14
Q

Mutation

A

change in the nucleotide sequence of an organism’s DNA

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15
Q

where do most mutations occur

A
  • Most mutations occur in somatic cells + lost when individual dies
  • Only mutations in gametes can be passed onto offspring
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16
Q
A
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16
Q
A
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17
Q

Mutation rate

A

tend to be low in animal in plants + more rapid in microorganism

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18
Q

Mutation

Change from generation to generations

A

Change from generation to generations is very small

19
Q

Sexual recombination importance

A

In sexually reproducing populations→ sexual recombination is far more important than mutations in producing genetic differences that make adaptation possible

20
Q

Sexual recombination

Change from generation to generation

A

Change from generation to generation → very small
Mostly reshuffling

21
Q

Genetic drift

A

random evolutionary change in a population

22
Q

Genetic drift

More likely in a ________ population

A

More likely in a small population than in a large population

23
Q

Genetic drift

Describes how allele frequencies can ___________

A

Describes how allele frequencies can fluctuate unpredictably from one generation to the next

24
Q

what am I

Alleles may be eliminated from population purely by chance Regardless of beneficial or harmful

A

Genetic drift

25
Q

Genetic drift

Decreases genetic variation ______ a population
Increases genetic differences ________ populations

A

Decreases genetic variation within a population
Increases genetic differences among different populations

26
Q

The bottleneck effect

A
  • A sudden change in the environment (fire) can drastically reduce side
  • By chance alone, certain alleles may be overrepresented, others underrepresented
27
Q

what am I

Major factor altering allele frequencies

A

Genetic drift + Gene flow

28
Q

Genetic drift will continue to change the gene pool until what

A

Genetic drift will continue to change the gene pool until the population is large enough to eliminate the effect of chance fluctuations

29
Q

The founder effect

A
  • Occurs when a few individuals become isolated from a larger population
  • Small fraction of population establishes a new colony + Bring with them only small fraction of genetic variability of OG
30
Q

Gene flow

A
  • Results from the movement of fertile individuals
  • Migration of breeding individuals → movement of alleles
31
Q

what am I

May cause a population to lose alleles (loose genetic variability) and others to gain some (increase genetic variability)

A

Gene flow

32
Q

what does gene flow counter

A

Counters genetic drift and natural selection, and microevolution

33
Q

what am I

Only mechanism that consistently causes adaptive evolution

A

Natural selection

34
Q

Natural seleciton Can alter the frequency distribution of heritable traits in 3 ways:

A
  1. Directional selection
  2. Distributive selection
  3. Stabilizing selection
34
Q

Evolution by natural selection is a blend of chance and “sorting:

A
  • Chance → creation of new genetic variation (mutation)
  • Sorting → favors some alleles over others
34
Q

Directional selection

A

shifts over makeup of population by factoring variants at one extreme of the distribution

35
Q

Natural selection = _________

A

Natural selection = adaptive evolution

36
Q

Distributive selection

A

favors variants at both ends of the distribution

37
Q

Natural selection leads to adaptation, but the process __________

A

Natural selection leads to adaptation, but the process does not involve trying

37
Q

Sexual selection shuffles existing alleles + deals them at random

3 processes

A
  • Crossing over
  • Independent assortment
  • Random fertilization
38
Q

Stabilizing selection

A

removes extreme variants from the population and prevents intermediate types

39
Q

Natural selection and sexual reproduction

A

In organisms that reproduce sexually → most genetic variation results from the unique combination of alleles that each individual receives

40
Q

natural selection + intentions

A

NS has no intentions or senses → can’t sense what a species needs

41
Q

NS cannot fashion perfect organisms

4 reasons why

A
  1. Evolution is limited by historical constraints
  2. Adaptations are often compromises
  3. Not all evolution is adaptive
  4. Selection mostly only edits existing variations
42
Q

Adaptations are often compromises

A
  • Organisms are often faced with conflicting situations that prevent an organism from perfecting any one feature for a particular situations
  • Changing one feature for the better might change another for the worse
43
Q

Not all evolution is adaptive

A

Chance affects the genetic structure of populations

44
Q

Selection mostly only edits existing variations

A

Selection favors only the fittest variations from those traits that are available
New generations do not arise on demand

Biology (12 decks)

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