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Mechanisms Of Evolution > Unit 3 (final 12/11) > Flashcards

Unit 3 (final 12/11) Flashcards

1
Q

Quantitative Genetics

A

The study of genetic basis underlying phenotypic variation among individuals
- continuous
- polygenic: one trait controlled by MANY genes
- effected by environmental factors

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2
Q

In a population of clones, how would their heights look?

A

Human height is controlled by 180 different genes, each with fairly small effects. Genotypes can yield a range of different phenotypes depending on the environment

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3
Q

To measure variation between phenotypes (Vp)

A

Subtract the smallest (height, weight, etc.) from the largest

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4
Q

Vp = Vg + Ve + C

A
  • Vg: variation because of genes
  • Ve: variation due to the environment
  • C: unknowns (variation due to random events)
    FORMULA PHENOTYPIC VARIATION
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5
Q

What is genetic heritability determined by?

A

The slope of the line
- no slope = no heritability

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6
Q

When is a trait heritable vs. non-heritable?

A
  • non: when there is no GENETIC affect
  • heritable when there’s no environment affect
  • SLIGHTLY heritable: an environmental affect
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7
Q

VA = 1, VP = 1

A

Trait is heritable
- no environmental affect

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8
Q

VA = 0, VP = 1

A

Non-heritable
- no genetic effect

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9
Q

VA = 1, VP = 2

A

Slightly heritable
- environmental effect

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10
Q

Mid-offspring

A

Offspring average

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11
Q

Mid-parent

A

Parent average

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12
Q

If we KNOW the heritable of a trait, we can predict….?

A

How natural selection will affect it

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13
Q

R = h^2xs

A

Breeder’s equation
- R: the response to selection in the offspring generation (how the population will change in the future)
- S: the selection differential in the parent generation
- used to predict the response to a particular strength

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14
Q

How can we identify the genes/alleles that determine certain traits?

A
  • experiment-based
  • data-based
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15
Q

Experiment-based

A

Can only be done with species that can interbreed and have short lifespans
- inbreed, cross species, select specific phenotype you want, inbreed again, genome sequence

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16
Q

Data-based

A

Can only be done with hundreds of thousands of points (manhattan plot)
- because every change in DNA is technically a different allele, we can do this analysis for each nucleotide position in a genome

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17
Q

Can genetic drift, by itself, change the behavior of animals over time?

A

Drift, by itself, without natural selection, might fix one allele over the other. So, yes.
- more evident in smaller populations, though

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18
Q

What are the three major categories organisms invest their resources into?

A

1) growth
2) defense
3) reproduction

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19
Q

What three things determines fitness?

A

1) Survival to mating age
2) Fecundity
3) mating success
- if there’s lacking in any one area, but the other two are strong, fitness is still good

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20
Q

Higher investment in growth and defense leads to lower what?

A

Reproduction rates

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21
Q

Physiological senescence

A

A by-product of life: “rate-of-living” theory
- only true within species, not when comparing species
- faster metabolic rates = faster aging
- if lifespan is set by psychological constraints, we should expect no genetic variance in populations (for lifespans)

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22
Q

Evolutionary senescence: forged by evolutionary processes

A

In a long enough time line, everyone’s survival rate drops to 0
- mutation accumulation
- The process of the decline in fertility and decline in probability of survival with age.

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23
Q

Antagonistic pleiotropy

A

Occurs when the fitness consequence of the affected traits run in the opposite direction
- poses a major strain on evolution

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24
Q

Pleiotropy

A

Alleleic variation influencing more than one phenotype

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25
Q

How does lifespan evolve in nature?

A

Higher mortality rates leads to bigger litters
- low defense, low growth, high in reproduction

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26
Q

Extrinsic mortality

A

mortality that is assumed to be a result of environmental hazards and be constant over age.

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27
Q

Intrinsic mortality

A

mortality that is assumed to be a result of aging and to increase over age,

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28
Q

Microevolution

A

Consisting of changes in allele frequency in a population over time

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29
Q

Macroevolution

A

Refers to broad patterns of evolutionary change above the species level

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30
Q

Biological species concept

A

Groups of organisms that can interbreed to produce viable, fertile offspring

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31
Q

Morphological species concept

A

NOT really useful
Good for: fossils, asexual, traditional classifications (when nothing else to work with ONLY)
- things that look the same and are hard to distinguish against each other

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32
Q

Cryptic species

A

Two species that look alike but cannot interbreed

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33
Q

Ecological species

A

Species that are co-occurring organisms that occupy different niches (or “adaptive zones”)

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34
Q

What are niches?

A

Adaptations to particular combinations or resource bases
- predators/parsites
- environmental factors in a particular place

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35
Q

Phylogenetic species concept

A

Smallest possible CLADE

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36
Q

Problems with ecological species concept

A
  • its impossible to define a niche extrinsically of the population occupying it
    • niches aren’t like parking spaces; species DO drive each other to extinction, but does that mean they weren’t species to begin with?
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37
Q

Problems with the biological species concept

A

Prokaryotes, amoeba, some animals, plants, fungi, isolated populations (because they’re too far to breed)
- all of these things may be apart of the same species but they are unable to breed with each other

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38
Q

Geographic modes of speciation

A
  • allopatry
  • vicariance
  • peripatetic divergence
  • parapatry
  • sympatry
  • species rings
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39
Q

Vicariance

A

Separation of large populations in two parts (ex. A random mountain forms)

40
Q

Peripatetic divergence

A

Allopatry caused by the colonization of a distant habitat from a larger population

41
Q

In both types of allopatry (vicariance and peripatetic divergence) what is the geneflow)

A

Geneflow = 0
- because geography results in an ABSOLUTE barrier to any gene flow between diverging populations

42
Q

Can drift play a role in both variations of allopatry?

A

Drift may play a role in peripatetic divergence
-

43
Q

Parapatry

A

Geographic separation, but not complete isolation
- often occurring in adjoins habitats (ex. Amazonia and Andes butterflies, moving elevations across mountains, depths in the ocean, etc.)
- become different enough to have 0 geneflow even though they can remain in contact

44
Q

Species rings

A

When a species has moved around the globe so much that it went in a circle and came back to its original population
- HOWEVER, by the time it returns, there’s no possible geneflow

45
Q

Sympatry

A

NO geographic separation among diverging populations
- hypothetical geneflow is pretty high

46
Q

Reproductive isolation methods (pre-zyotic: before fertilization)

A

1) Geographic
2) temporal
3) mechanical
4) gametic

47
Q

Reproductive isolation methods (post-zygotic)

A

1) hybrid invanility
2) hybrid sterility
3) hybrid depression

48
Q

Pre-zygotic geographic isolation

A

the organisms are separated geographically so they never meet to mate
- this is pre-zygotic because the zygote wont be created at all

49
Q

Pre-zygotic Temporal isolation

A

Different migration times make species reproductively isolated
- zygote wont ever be created

50
Q

Mechanical pre-zygotic isolation

A

a type of prezygotic barrier, where no fertilization occurs and thus reproduction does not occur
- any physical barrier that prevents mating
- physical differences in genitalia prevents mating

51
Q

Gametic pre-zygotic isolation

A

gametes (egg and sperm) come into contact, but no fertilization takes place

52
Q

Post-zygotic hybrid inviability

A

a situation in which a mating between two individuals creates a hybrid that does not survive past the embryonic stages
- no viable offspring

53
Q

Post-zygotic sterility

A

zygote is able to develop into healthy offspring. However, they are unable to produce offspring and, therefore, unable to pass on their genetic material

54
Q

Post-zygotic hybrid depression

A

the loss of heterozygosity in a population leading to a decline in fitness

55
Q

Evolutionary ecology

A

a field within in both ecology and evolution that examines how interaction between and within species evolve, and the interactions between species and their environment
- considers how the evolutionary effects of competition, mutualists, predators, prey, and pathogens (how species interact with their environment and how those interactions change their evolution)

56
Q

Intra species

A

Competition between individuals within the same species

57
Q

Inter species

A

Competition between individuals from different species

58
Q

Evolutionary time

A

Generations

59
Q

Ecological time

A

The right now
- day-to-day

60
Q

What happens to the diversity and intensity of the species at a MACROevolutionary scale?

A

It increases

61
Q

What effect does competition have on fitness?

A

Decreases it

62
Q

When you have two positive interactions, what kind of overlap do you want?

A

Higher
- ex. Pollination. More pollination = more reproduction = higher fitness

63
Q

When there’s more overlap, what does selection look like?

A

There’s greater pressure to REDUCE overlap

64
Q

Where is limiting similarity expected to be strongest?

A

The tips of phylogenies
- as soon as a species slips, they are more similar than they ever will be again. The pressure to be different is at its highest point
- the older they become, the more different they become, so the pressure lessens

65
Q

Convergent evolution

A

the independent evolution of similar features in species of different periods or epochs in time.
- creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups.

66
Q

What effects does limiting similarity via creation of new niches have?

A

1) maximizes differences between species
2) decreases competition

67
Q

What does maximizing differences between species do?

A

Reduces their negative interactions

68
Q

As new species emerge, what happens to niche availability?

A

It becomes smaller
- evolutionary of ecological niches is expected to create specialization as they become narrower

69
Q

The specialization paradox

A

The interaction between diversity and competition is expected to reduce niche overlap and increase ecological specialization
- BUT, in diverse ecosystems, generalist species are common

70
Q

Generalist species

A

A species able to thrive in a wide variety of environmental conditions and that can make use of a variety of different resources

71
Q

Adaptive radiation

A

Something happens in time where a lineage explodes and diversifies like crazy because they have a key innovation (open market; no competition)
- explosion leads to speciation that competes with each other/occupies niches

72
Q

Key innovations

A

novel phenotypic trait that allows subsequent radiation and success of a taxonomic group.

73
Q

What do changes in niches do?

A

Allows species to jump to NEW niches which are empty of competition

74
Q

What happens to niches when there’s no competition?

A

They become empty

75
Q

Altruism

A

When a behavior of an organism benefits others at a cost of their own lives

76
Q

Selfishness

A

A behavior which is beneficial to the actor and costly to the recipient

77
Q

Spite

A

A behavior which is costly to both the actor and the recipient

78
Q

Cooperation

A

A behavior which provides a benefit to another individual and which is selected for because of its beneficial effect on the recipient

79
Q

Intra-sexual selection

A

Mating sexual selection determined by within-sex interactions

80
Q

Inter-sexual selection

A

Mating success determined by between-sex interactions

81
Q

Polygamy

A

Any system where individuals mate with multiple individuals in the population

82
Q

Polygyny

A

When males mate with multiple females

83
Q

Polyandry

A

When females mate with multiple males

84
Q

When is polyandry favored? What is the consequence?

A

When males become limiting resources for reproduction
- when females are choosy
- when low offspring survival required male parental care, so that males have the greater reproductive effort and lower reproductive rate
Consequence: sexual selection is stronger

85
Q

What is additive genetic variation?

A

Additive effect of individual genes in the phenotype
- three different genes affect height, one of them makes it one inch taller REGARDLESS OF WHAT OTHER ALLELES MAY DO

86
Q

Epistatic (interaction) genetic variance

A

How different genes that effect the same trait interact with each other

87
Q

Co-evolution

A

Reciprocal evolutionary change between interacting species driven by natural evolution

88
Q

Can species exist in isolation?

A

No, they have to interact with each other and the environment to acquire resources
- must compete with each other resources, even if this may be indirectly

89
Q

If selective pressures are likely to change the allele frequency of a species, what else changes?

A

The average phenotype of a species

90
Q

Changes in genetics

A

Big, RANDOM, mutations in allele frequencies

91
Q

Evolutionary arms race

A

One species is evolving their defense mechanisms (ie. plants) and the other one is evolving ways to overcome them (insects)

92
Q

Escalation

A

Coadaptations become increasingly powerful/effective

93
Q

What happens to a co-dependent species when one of them splits (becomes evolutionary independent)

A

The other splits at the exact same time

94
Q

Mutualistic relationship

A

When two organisms of different species work together
- each benefit from the relationship

95
Q

Parasitism

A

A non-mutualistic relationship where one species (parasite) benefits and from the other (host)

96
Q

Symbiotic relationship

A

When two organisms are in a symbiotic relationship cause one cannot survive without the other

97
Q

Commensalism

A

An association where one benefits and the other isn’t harmed, but doesn’t benefit either

Mechanisms Of Evolution (1 decks)

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