Biol 213 > Midterm 2 > Flashcards

Midterm 2 Flashcards

(94 cards)

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1
Q

Genetic drift

A

Evolution by random change in allele frequencies

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2
Q

Where does genetic drift occur most?

A

Smaller populations

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3
Q

Does genetic drift increase or decrease genetic variation within populations?

A

Decrease

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4
Q

Does genetic drift increase or decrease genetic variation between populations?

A

Increase

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5
Q

Bottleneck

A

Temporary reduction in population size leading to genetic drift

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6
Q

Founder effect

A

A new isolated population is established by a small number of individuals separated from a larger population. It is a form of genetic drift.

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7
Q

What happens when fitness is independent of phenotype

A

No selection and no drift occurs

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8
Q

Directional selection

A

Occurs when fitness increases or decreases as the trait increases. Evolves the trait mean.

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9
Q

Stabilizing selection

A

Average individuals have higher fitness than extreme individuals. Variance decreases between generations, but trait mean does not change.

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10
Q

Disruptive selection

A

Extreme phenotypes are favored, and intermediate phenotypes are selected against. Average individuals have lower fitness.

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11
Q

Frequency dependent selection

A

Fitness of phenotypes depends on how rare or common the phenotype is in the population. Example: lizard species.

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12
Q

Sexual selection

A

Variation in the ability to acquire and fertilize mates. Might favour different traits than natural selection and may evolve costly traits.

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13
Q

Bateman’s principal

A

Males show greater variability in reproductive success

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14
Q

Sexual dimorphism

A

Male and female phenotypes are different

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15
Q

Sexual monomorphism

A

Males and females have the same phenotype

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16
Q

Intrasexual selection

A

Fitness differences resulting from differing abilities of members of the same sex to compete for mating opportunities

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17
Q

Intersexual selection

A

Fitness differences resulting from preferential mating between specific males and females

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18
Q

Assortatative Mating

A

Individuals with similar genotypes and/or phenotypes mate with one another more or less frequently than would be expected under a random mating pattern

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19
Q

Inbreeding

A

Meeting with close relatives. Changes genotype frequencies, but not alle frequencies by itself produces more homozygous offspring than from out crosses.

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20
Q

Mating with more distant relatives

A

Outbreeding

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21
Q

Hermaphroditic

A

Plants that can fertilize themselves

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22
Q

Speciation

A

The process by which new species arise, a.k.a. formation of biodiversity

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23
Q

Population divergence

A

Populations accumulate fixed differences and become so genetically divergent that mating between individuals of different populations fails. Driven by genetic drift or natural selection.

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24
Q

Allopatric speciation

A

Occurs in different places due to a physical barrier dividing the geographic range called a vicarious event. Gene flow ceases and populations evolve independently eventually alleles may become fixed. If physical barriers are removed populations may or may not remain distinct.

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25
Sympatric speciation
Occurs in the same place with no physical barrier. Disruptive selection, results into genetically distinct populations which diverge and can become two distinct species.
26
Polyploidization
Occurs when meiosis fails and organisms produce diploid instead of haploid gametes. If two diploid gametes are fertilized it produces an autopolyploid, which can only mate with each other, causing reproductive isolation.
27
Prevention of mixing gene pools
Reproductive isolation
28
Pre-zygotic isolation
Reproductive isolation before fertilization and zygote production
29
Post zygotic isolation
Reproductive isolation after fertilization and zygote formation
30
Individuals that look alike
Morphological similarity
31
Reproductive species concept
Ability to produce offspring
32
Phylogenetic
shared evolutionary history
33
Morphological species concept
Groups species by how similar they appear. Does not include genetic or evolutionary justification and may be arbitrary.
34
Biological species concept
Considers species to be groups of actually or potentially interbreeding populations that are reproductively isolated from other groups. Uses clear criteria, but may be difficult to distinguish in the field and does not apply to asexual species.
35
Phylogenetic species concept
Constructs an evolutionary tree, using morphological and genetic sequence data. Useful for asexual species and can be applied to any group of organisms.
36
Subspecies
Variance of a species, such as easily recognized phenotypic variation
37
Ring species
Live in a ring shaped distribution surrounding uninhabitable terrain. Gene flow only occurs between adjacent populations
38
Cline
Pattern of variation of a trait across geographic gradient
39
Phylogeny
A way to quantify how diversity changes overtime
40
Phylogenetic tree
A branching diagram that shows the relationships between species according to the time since a common ancestor
41
Sister groups
Two species or groups of species that share a common ancestor, not shared by any other species or group
42
Phylogenetic tree with time scale
Phylogram
43
Phylogenetic trees with equal length branches
Cladogram
44
Monophyletic group
Includes a common ancestor and all of its descendants
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Paraphyletic group
Includes a common ancestor and some, but not all of its descendants
46
Polyphyletic group
Does not include the common ancestor
47
Information used to infer phylogenies
Characters that vary between but not within species and have a genetic basis. Including morphological, chromosomal, and molecular.
48
Homologous characters (homologies)
Characters shared because of common ancestry. Shared ancestral and derived characters.
49
Analogous characters (homoplasies)
Characters with similar appearance or function that developed separately. Shared because of convergent evolution not ancestral.
50
Synapomorphies
Homologies shared by some, but not all species groups
51
Most parsimonious
Strongest hypothesis of evolutionary relationships. The tree with the fewest number of changes required.
52
Distance methods
Comparing DNA sequences to estimate the degree of relatedness. Differences in DNA sequence can evolve by drift or selection and the more differences the further the species are related.
53
Macro evolution
Evolution above the species level. For example, the diversity of an entire clade and its position on the tree.
54
Adaptive radiation
Rapid evolution of new species occupying new niches
55
Anagenesis
Speciation where the ancestor species is fully replaced by a new species. Evolution within a lineage.
56
Cladogenesis
Parent species splits into two species
57
Graduated evolution
Slow and gradual evolution. Results in more anagenesis. Occurs due to intense competition, low, genetic diversity, small population size and high specialization.
58
Punctuated evolution
Rare and rapid (on a geological times scale) events of branching speciation. Results in more cladogenesis. Occurs due to colonization of a new area, diversification following a mass extinction event, or evolution of a new trait that opens up a new niche.
59
Divergent adaption to different pressures
Branches adapt individually to suit the different pressures
60
Adaption to similar pressures
Branches adapt similarly but individually to a single optimum model
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Genetic drift with no selective pressure adaption
Branches adapt individually and apparently randomly
62
Endotherms
Organisms that regulate their body temperature. Require much higher energy per gram than ectotherms. Often show determinant growth.
63
Ectotherms
Conform to environmental temperatures. Require less energy per gram than endotherms. Often show indeterminant growth.
64
What organisms require higher total energy?
Larger organisms
65
What organisms require higher energy per gram?
Smaller organisms
66
Allometric coefficient
Equivalent to slope and indicates the scaling relationship in a log transformed relationship
67
a=1
Isometric. The parameter increases proportionally with increasing mass.
68
Allometry
Scaling relationships
69
a>1
Hyper metric. The parameter increases to a greater proportion with increasing mass.
70
a<1
Hypo metric. The parameter increases to a lesser proportion with increasing mass.
71
Energy scaling in mammals
Increases hypo metrically with mass. a~0.75
72
Microbes
Use much lower energy requirements. Less complex, less energy to move nutrients into cells, and use asexual reproduction.
73
Primary goal of managing an energy budget
Have energy remaining to reproduce (for all) and raise offspring (for some)
74
Life history traits
Energy strategies to maximize lifetime reproductive success/fitness. Caused by natural selection.
75
Passive care
Pre-birth energy investment. For example, seed development or gestation.
76
Active care
Post birth energy investment. For example, raising offspring.
77
Parity
How often an individual reproduces
78
Semelparity
Individuals can only breed once in their lifetime
79
Iteroparity
Individuals can breed more than once in their lifetime
80
Natural selection favours…? (Reproduction)
Strategy that produces most descendants (usually)
81
Life history table
Shows data such as age, population size, fecundity, survivorship
82
X
Age
83
Nx
Number of females at age x
84
Sx
Survival rate from one age to the next. N2/N1
85
Lx
Survivorship. Fraction of original cohort still alive. Nx/No
86
Mx
Fecundity. Average number of females offspring per living female.
87
Ro
Net reproductive rate. Average number of female offspring per female in cohort over the cohort’s lifespan. Sum of LxMx for each x.
88
Ro=1
Population is stable
89
Ro<1
Population is decreasing
90
Ro>1
Population is increasing
91
Survivorship Curves
Plot Lx with a log scale
92
Type 1 survivorship curve
Low mortality until end of life, large animals, few young, high parental care and high juvenile survivorship
93
Type 2 survivorship curve
Linear. Constant rate of mortality through lifespan
94
Type 3 survivorship curve
Low juvenile survivorship, mortality rate decreases with age
Biol 213
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