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Intro To Biology (for Vet Techs) > Evolution By Means Of Natural Selection > Flashcards

Evolution By Means Of Natural Selection Flashcards

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1
Q

Natural Selection Requires:

A

-variation in individuals
-variation is heritable
-more offspring produced than can survive
-some individuals are better at surviving and/or reproduction than others

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2
Q

Darwin identified 4 conditions necessary for natural selection to operate:

A
  1. There’s a variation in the traits of individuals within a population.
  2. The variation in these traits is heritable, so they can be passed from parents to offspring.
  3. More offspring are produced than can survive (because the environment has limited resources).
  4. Some individuals are better adapted for survival and reproduction in their environment than others (based on differences in their traits).
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3
Q

Competition between members of the SAME species.

A

Intraspecific Competition

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4
Q

Competition against other species.

A

Interspecific Competition

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5
Q

The big-picture idea that species diversify over long periods, eventually forming clusters of closely related groups.
Can lead to speciation.

A

Macroevolution

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6
Q

Formation of a new species.

A

Speciation

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7
Q

More concerned with eh details of how evolution occurs. —> Focusing on changes in allele frequencies within shorter periods

A

Microevolution

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8
Q

Studies the prevalence of alleles in a population and how populations differ genetically.

A

Population Genetics

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9
Q

An individual gene controls one trait.
1 gene, 1 trait

A

Single-Gene Trait

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10
Q

Many genes acting together to produce a single trait.
many genes, 1 trait

A

Polygenic Trait

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11
Q

When a single gene influences more than 1 trait.

A

Pleiotrophy

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12
Q

Single-gene trait
Natural selection increases the frequency of an allele in a population when the allele codes for an adaptive trait and causes maladaptive alleles to decrease in frequency (or even disappear).
The fitness of a phenotype depends on its relative frequency within a population.

A

Frequency-Dependent Selection

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13
Q

Single-gene trait
Rare phenotypes have an advantage and natural selection makes them more common.

A

Negative Frequency-Dependent Selection

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14
Q

Single-gene trait
Adaptive advantage over homozygous.
Sometimes, having copes of different alleles make a heterozygous individual more fit than either homozygous individual.

A

Heterozygote Advantage

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15
Q

Natural selection affects/influences polygenic traits in 3 ways:

A

-Directional Selection
-Stabilizing Selection
-Disruptive Selection

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16
Q

How natural selection affects polygenic traits
Favors and extreme phenotype (so the population average shifts to the left OR to the right).
1 extreme, direction shift (1 way).

A

Directional Selection

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17
Q

How natural selection affects polygenic traits
Favors intermediate phenotypes (narrowing the distribution along the bell curve).
Average phenotype is preferred.
Tightening distribution.

A

Stabilizing Selection

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18
Q

How natural selection affects polygenic traits
Favors 2+ phenotypes while the average is unfavorable.
More significant changes can be seen within the species. —> Can lead to the evolution of different morphs, subspecies, and even new species.
Favors extreme but NOT intermediate, separate morphs evolve.

A

Disruptive Selection

19
Q

A random change in allele frequencies over time.
More likely to affect smaller populations because they have less genetic variation.

A

Genetic Drift

20
Q

Genetic drift in larger populations can occur if the population size is dramatically reduced. —> In this case, any surviving individuals have a disproportionately high contribution to the gene frequencies within their dependents.

A

Population Bottleneck

21
Q

A type of population bottleneck that occurs when only a few individuals form a new population in an isolated area. —> This isolated population contains only a small amount of genetic variation from the original population.
New species can arise if a population is reproductively isolated.

A

Founder Effect

22
Q

p^2 + 2pq + q^2 = 1
p + q = 1

p = homozygous dominant
pq = heterozygous
q = homozygous recessive

A

Hardy-Weinberg Equation

23
Q

Applies to populations at equilibrium that aren’t evolving. —> Explained how allele frequencies remained constant over time.
States that allele frequencies in a population remain constant over time if 5 conditions are met: there are no mutations, population size is large and not affected by genetic drift, population is isolated (no gene flow), mating occurs randomly, and natural selection isn’t occurring.
Assumptions of this area rarely met…

A

Hardy-Weinberg Principle/Law

24
Q

Genetic information being transferred between populations.

A

Gene Flow

25
Q

Conditions that must be met for allele frequesies in a population to remain constant:
Hardy-Weinberg Principle/Law

A

-There are no mutations.
-The population size is large and not affected by genetic drift.
-The population is isolated from other populations (no immigration, emigration, or other types of gene flow).
-Mating occurs randomly.
-Natural selection isn’t occurring.

26
Q

The formation of a new and distinct species (in the course of evolution).

A

Speciation

27
Q

The inability of a species to reproduce with related species.

A

Reproductive Isolation

28
Q

Reproductive Isolation
Occurring before fertilization. —> Prevents the zygote from being formed.

A

Prezygotic Isolation

29
Q

Prezygotic Isolation
Geography separates species or the species find mates in different habitats.
(ex. rivers or mountain rangers, some individuals might establish themselves in a new area)

A

Habitat Isolation

30
Q

Prezygotic Isolation
The species mate during different seasons or times of the day.

A

Temporal Isolation

31
Q

Prezygotic Isolation
Organisms aren’t attracted to each other. —> Many animals have specific mating rituals that they use to attract mates.

A

Behavioral Isolation

32
Q

Prezygotic Isolation
The species are physiologically different enough to NOT be able to mate.

A

Mechanical Isolation

33
Q

Prezygotic Isolation
Gametes from the 2 species are unable to fuse to form a zygote.

A

Gamete Isolation/Genetic Isolation

34
Q

Reproductive Isolation
Occurring after fertilization. —> Affects the zygote after it’s formed.

A

Postzygotic Isolation

35
Q

Postzygotic Isolation
An egg is fertilized but the zygote can’t mature to form offspring.

A

Zygote Mortality

36
Q

Postzygotic Isolation
Offspring can be formed but still have a high mortality rate.

A

Hybrid Inviability

37
Q

Postzygotic Isolation
Hybrid offspring are unable to reproduce.
(ex. mules)

A

Hybrid Sterility

38
Q

Speciation
If habitat isolation causes 2 populations to become reproductively isolated, natural selection may drive these geographically isolated populations to become different species.

A

Allopatric Speciation

39
Q

Speciation
A subpopulation is established on the edge of a main population’s habitat becomes a new species (over many generation). —> One population is MUCH smaller than the other.

A

Peripatric Speciation

40
Q

Speciation
Subpopulations of a species have different ranges but overlap with each other at least somewhat. —> Tend to mate with geographic neighbors.
Instead of being separated by a physical barrier, differences int eh same environment separate the species.

A

Parapatric Speciation

41
Q

Speciation
Formation of new species without geographic isolation. RARE
Barriers to gene flow sometime develop without a physical or geographic barrier.

A

Sympatric Speciation

42
Q

Speciation
The evolution of a single species into diverse species adapted to specific niches.
Diversification of species into many niches. —> Happens most rapidly if a change in the environment creates new niches or makes additional resources available.

A

Adaptive Radiation

43
Q

When a large number of living species goes extinct in a relatively short time. —> Often followed by periods of high adaptive radiation and speciation.

A

Mass Extinction

44
Q

The idea that some species survive a catastrophic even that leads to mass extinction while others don’t.

A

Catastrophic Species Selection

Intro To Biology (for Vet Techs) (23 decks)

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