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Animal Form and Systematics > AFS Exam 1 > Flashcards

AFS Exam 1 Flashcards

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1
Q

Evolution

A

Change in the genetic composition of populations over time.

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2
Q

Evolutionary Theory

A

Overarching understanding of the processes of evolutionary change.

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3
Q

Scientific Theory

A

Explanation of an observed, natural phenomenon. Evolution qualifies. NOT an untested hypothesis.

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4
Q

Which two people independently arrived at the idea of evolution by natural selection and coauthored and presented to the Linnean society? (July 1858)

A

Charles Darwin and Alfred Russel Wallace.

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5
Q

Nov. 1859 Darwin solidified his theory of evolution by natural selection through the publication of ______?

A

On the Origin of Specieis by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.

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6
Q

The Modern Synthesis (Neo-Darwinian Theory)

A

Fusion of Mendelian genetics with Darwinian evolutin, resulted in an unified theory of evolution.

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7
Q

What are the Four Postulates of Natural Selection?

A
  • Variation
  • Heritability
  • Overproduction
  • Nonrandom Survival and Reproduction
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8
Q
  1. Variation
A

Source of variation is mutation, individuals withing a species are variable.

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9
Q
  1. Heritability
A

Some variations are passed on to offspring.

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10
Q
  1. Overproduction
A

In every generation, more offspring are produced than can survive.

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11
Q
  1. Nonrandom Survival and Reproduction
A

Individuals that survive and reproduce (the most) are those with the most favorable variations, they’re naturally selected.

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12
Q

Fitness

A

The extent to which an individual contributes genes to future generations.

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13
Q

Adaptation

A

Favored trait that increases the ability to survive or reproduce, this spreads through a population by natural selection.

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14
Q

Evolution by natural selection occurs at the
______ _____, yet it results in changes to a
______’s gene pool.

A

individual level, population

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15
Q

Selection can act only on alleles that

are ________ expressed.

A

phenotypically

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16
Q

_____ ______ can occur when traits

vary along an environmental cline.

A

Clinal variation

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17
Q

Descent with modification

A

Refers to the passing on of traits from parent organisms to their offspring. This passing on of traits is known as heredity, and the basic unit of heredity is the gene.

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18
Q

Directional selection

A

favors individuals that vary in one direction, extreme phenotype is varied.

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19
Q

Disruptive selection

A

favors individuals that vary in both directions from
the mean. example: Light-colored oysters would blend into the rocks in the shallows, and the darkest would blend better into the shadows. The ones in the intermediate range would show up against either backdrop, offering those oysters no advantage and make them easier prey

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20
Q

Fixed allele

A

An allele that is the only variant that exists for that gene in all the population. A fixed allele is homozygous for all members of the population. . If there is only one allele at a locus, its frequency = 1. The population is monomorphic at that locus; the allele is said to be fixed.

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21
Q

founder effect

A

When a small population colonizes a
new region.
§ The colonizing population is unlikely to
have all the alleles present in the whole
population.

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22
Q

Frequency-dependent

selection

A 
A polymorphism can be
maintained when fitness
depends on its frequency
in the population. Different alleles of a gene
may be advantageous
under different
environmental conditions.
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23
Q

gene flow

A

results from the migration of individuals and movement of

gametes between populations.

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24
Q

gene pool

A

the sum of all copies of all alleles at all loci in a population.

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25
genetic drift
results from random changes in allele frequencies.
26
genetic structure
Allele frequencies at each locus and genotype frequencies. How genetic structure of a population changes over time is a measure of evolutionary change.
27
Hardy-Weinberg equilibrium
The Hardy–Weinberg equilibrium describes a model situation in which allele frequencies [the genetic structure of a population] do not change. Genotype frequencies can be predicted from allele frequencies.
28
macroevolutionary
(large-scale, long-term) patterns across species | sometimes require additional explanations
29
microevolutionary
(smallscale, short-term) processes within populations.
30
Muller's ratchet
—mutations accumulate or | “ratchet up” at each replication
31
mutation
any change in the nucleotide sequences of DNA and the origin of genetic variation. the fuel of new variation.
32
Neutral alleles
Alleles that do not affect fitness. They are added to a | population by mutation.
33
Nonrandom Survival and Reproduction
The individuals that survive and go on to reproduce, or who reproduce the most, are those with the most favorable variations. They are naturally selected.
34
Population bottleneck
Environmental conditions result in survival of only a few individuals. Genetic drift can reduce genetic variation in the population.
35
Positive selection
Referring to a single gene locus, a particular | variant may be favored—
36
purifying selection
selection against any deleterious mutations
37
Qualitative traits
Influenced by alleles at only one locus (e.g., smooth | vs. wrinkled).
38
Quantitative traits
Show continuous variation; are influenced by alleles at more than 1 locus. Example: Distribution of body size in a population is likely to resemble a bell-shaped curve.
39
sexual selection
A form of nonrandom mating that favors traits that increase the chances of reproduction.
40
stabilizing selection
preserves the average phenotype.
41
trade-off
when one trait cannot increase without a decrease in another
42
Ancestral trait
an evolutionary trait that is homologous within groups of organisms (see homology) that are all descended from a common ancestor in which the trait first evolved.
43
Apomorphy
– derived character state (trait)
44
autapomorphy
An evolved character or trait that is unique to a single | species or group within a larger phylogenetic group.
45
clade
A taxon that consists of all the descendants of a common ancestor
46
cladistic approach
based on creating monophylies through | phylogenetic trees
47
[cladistics]
In cladistics all natural groups (clades), consist of an ancestor and all of that ancestors descendants, and nothing else.
48
convergent evolution
The process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
49
convergences
evolved separately in | independent lineages
50
divergent evolution
the accumulation of differences between groups which can lead to the formation of new species.
51
reversals
evolved from a derived condition back to the primitive condition
52
homologous
Features shared by two or more species that were | inherited from a common ancestor
53
homoplasy
representing similarities not inherited directly from a common ancestor but are instead convergences (evolved separately in independent lineages) or reversals (evolved from a derived condition back to the primitive condition).
54
ingroup
The group of primary interest
55
maximum likelihood
Computer programs are now used to analyze traits and construct trees using a maximum likelihood method.
56
molecular clock
Average rate at which a gene | or protein accumulates changes.
57
monophyletic [monophyly]
a group containing the most recent common ancestor AND all its descendants
58
Occam’s razor
the best explanation fits the data with the fewest | assumptions.
59
outgroup
a closely related species or group known to be outside the group of interest.
60
paraphyletic [paraphyly]
a group containing the most recent common | ancestor, but NOT all the descendants
61
parsimony principle
The simplest explanation of observed data is the | preferred explanation.
62
phenetic approach
based on the above approach, but uses a | numeric system of weighting characteristics; sometimes referred to as taximetrics.
63
phylogenetic tree
Phylogenetic trees are typically constructed using | hundreds or thousands of traits. Linneages can rotate around nodes.
64
phylogeny
is the evolutionary history of relationships | among organisms or their genes
65
plesiomorphy
the ancestral trait
66
polyphyletic [polyphyly]
a group that does not include the common ancestor of the group
67
root
common ansestor on a phylogenetic tree
68
sister clades
Two clades that are each other’s closest relatives
69
sister species
Two species that are each other’s closest relatives
70
symplesiomorphy
a shared ancestral trait between two taxa
71
synapomorphy
a trait shared between taxa and the most recent | common ancestor
72
taxon
any group of species that we designate or name (e.g., vertebrates).
73
Binomial Nomenclature
Linnaean organizational structure: Kingdom-Phylum-Class-Order-Family-Genus-Species
74
allopatric speciation
occurs when populations are separated by a physical | barrier
75
allopolyploidy
Combining chromosomes from two species, often via | hybridization.
76
autopolyploidy
: Chromosome duplication in a single | species [Gray Treefrog and Cope’s Gray Treefrog].
77
biological species concept
Groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups.The biological species concept does not apply to organisms that reproduce asexually,and it is limited to a single point in evolutionary time.
78
lineage species concept
Species as branches on the tree of life; includes asexually reproducing species.
79
morphological species concept
Members of species look | alike because they share many alleles.
80
polyploidy
Sympatric speciation most commonly occurs by | polyploidy—duplication of whole sets of chromosomes.
81
sympatric speciation
speciation without physical isolation
82
species
Groups of organisms that mate with one another.
83
speciation
the divergence of biological lineages and emergence of reproductive isolation.
84
sister species
Many sister species (each other’s closest relatives) exist on either side of a geographic barrier
85
reproductive isolation
when groups can no longer exchange genes; it is | a key factor in the divergence of sexually reproducing organisms.
86
prezygotic isolating mechanisms
Prevent hybridization from occurring: § Mechanical: differences in size and shape of reproductive organs makes mating impossible § Temporal: mating periods do not overlap. § Behavioral: individuals reject or fail to recognize potential mating partners. § Habitat: When two closely related species evolve preferences for living or mating in different habitats. § Gametic: Eggs of one species do not have appropriate chemical signals for sperm of another species; or sperm is not able to attach to and penetrate the egg.
87
postzygotic isolating mechanisms
Reduce the fitness of hybrid offspring: § Low hybrid zygote viability: zygotes fail to mature or have severe abnormalities. § Low hybrid adult viability: offspring have lower survival rates. § Hybrid infertility: offspring are infertile (e.g., mules)

Animal Form and Systematics (2 decks)

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