Midterm 2 Flashcards
1
Q
What is an adaptation?
A
A trait acted upon by natural selection to fulfill a particular function
2
Q
What are the steps to determining if something is from adaptation?
A
- identify a trait you want to figure out
- test if there is selection on trait and see if its evolution has a relationship w the environment
- demonstrate a link between the trait and fitness
- reject that its cus of selective neutrality
- determine that the trait can be inherited
- measure the heritability
- find the genes in control
3
Q
What did the sand mouse experiment test?
A
If fur color is an adaption to dunes
4
Q
What must be shown by a trait was brought up by adaptation?
A
Selection on that trait
5
Q
What are the axes for determining trait selection?
A
Y = Probability of survival
X = Trait scale
6
Q
What are the graph axes for showing heritability?
A
Y = freq of trait
X = time point
7
Q
What is convergent (parallel) evolution?
A
Similarity between species that is caused by a similar, but evolutionarily independent, response to a common environment problem
8
Q
Why is convergent evolution strong evidence for adaptation?
A
Natural selection of convergent evolution produces predictable changes in phenotype with respect to habitat
9
Q
What are the axes of a trait determining how its affected by environmental factors?
A
X axis = two different locations
Y axis = trait
10
Q
What is asexual reproduction?
A
offspring clones of their parent
11
Q
What is sexual reproduction?
A
Gives rise to offspring with unique combinations of alleles inherited from their biological parents
12
Q
What is isogamy?
A
All gametes are the same size
- some species, all gametes can fuse
- other species, only different mating types can fuse
13
Q
What is anisogamy?
A
Gametes are size-dimorphic
- only gametes of diff sizes can fuse
14
Q
What is a hermaphrodite?
A
A species that has large and small gametes
15
Q
What is the most important thing about sexual reproduction when it comes to inheritance?
A
RECOMBINATION
16
Q
Can something reproduce sexually and asexually?
A
Yes
17
Q
Why is sexual reproduction a paradox?
A
Math wise, sexual reproduction produces only half the children that asexuals do over generations so asexual reproduction should outcompete them over time
18
Q
What are the advantages of sex?
A
Removal of deleterious mutations and creating novel phenotypes that can adapt better to variable environments
19
Q
How long does it take for asexuals to gain a favorable genotype?
A
VERY long
20
Q
How long does it take to get a favorable genotype with sexual reproduction?
A
Very fast thanks to recombination
21
Q
What are the two main keys of recombination that make it good?
A
Allows for fixation of good mutations and removal of deleterious mutations
22
Q
What is Muller’s ratchet?
A
“The least-loaded class can be lost by chance”
In an asexual population, if the zero-mutation group is lost by chance, its gone forever
23
Q
What is genetic load?
A
Decrease in fitness due to deleterious mutations
24
Q
What does muller’s ratchet say about genetic load?
A
It increases over time, decreasing fitness over generations
25
Is self reproduction more similar to sexual or asexual reproduction?
Asexual cus ur using the same genes
26
When exposed to a mutagen, what is favored, sexual or asexual?
Sexual cus you can get rid of deleterious mutations
27
What is the Fisher-Muller effect?
Through recombination, competition is eliminated between beneficial mutations as they can be combined to speed up adaptation
28
What is Bet-hedging?
When the environment is unpredictable, its good to DIVERSIFY the gene pool through making offspring different from parents cus they’ll be more likely to have at least one that has advantageous traits
29
What is Host-parasite coevolution?
Parasites evolve to target common host genotypes, sex produces rare genotypes that make it hard for them to adapt to
30
What does the frequency dependent selection graph with host parasite coevolution look like?
X axis = host allele frequency
Y axis = parasite frequency
It looks like a loop with arrows following a circular pattern
31
What is the red queen hypothesis?
The host parasite loop
32
When is sex beneficial and not beneficial with host and parasite evolution?
Beneficial - both host and parasite evolve
Not beneficial - only host evolves
33
Why isn’t sex favored in hosts when the parasites dont evolve?
The host already won, it doesnt need new phenotypes to adapt to the parasite
34
When is sex more favored in hosts?
When parasites are common, tested in frequency of sexually reproducing snails that can choose sexual and asexual reproduction
35
What are the axes on the sexual selection gradient?
Y axis - mating success
X axis - flashy trait
36
What causes a sexual selection gradient?
Variation among individuals in success at getting mates, aka flashier traits make u more likely to mate
37
What is the reproductive success of the heavily investing parent (mom) limited by?
Resources and time
38
What is the reproductive success of the lightly investing parent (dad) limited by?
Number of mates
39
Who faces more competition to mate: males or females?
Males, further reasoning for sexual selection cus the men have to compete
40
What is the operational sex ratio?
Ratio of reproductively active males to females
41
When is competition among males highest?
When resources and females are limited
42
When sexual selection is strong, what can we predict?
- members of the sex with higher sexual selection will compete for mates
- members of the sex subject to weak sexual selection will be choosy
43
What is within-sex competition (intrasexual selection)?
Differential mating success due to interactions within members of the same sex (think goats fighting)
44
What is between-sex competition (intersexual selection)?
Differential mating success due to interactions with members of the other sex
45
What traits matter for sperm competition?
Number of sperm and sperm length
46
Who have longer sperm: external, spermcasters, or internal fertilizers?
Internal fertilizers cus of selection from sperm competition
47
What are four elements of sexual selection? (I didnt know how to word this)
1. Arbitrary
2. Pre-existing sensory bias
3. Direct benefits: resource acquisition
4. Indirect benefits: better genes for offspring
48
Arbitrary traits that are sexually selected which have no addition or reduction to fitness are part of the ___ model
Null
49
What potentially causes pre-existing sensory biases?
Selection on avoiding predators, finding food, etc.
50
What evolves first: the preference or the male displays?
Preference
51
What are some examples of direct benefit of acquiring resources?
Males providing food, parental care, or some other resources to the female
52
What do direct benefits to the female allow them to distinguish?
Which males provide more or less resources, the choosier the female the better
53
What are some examples of indirect benefit of better genes for their offspring?
Certain displays that indicate higher genetic quality (ex. Long calling frogs had stronger offspring than short calling men)
54
Does sexual selection happen in plants?
Yes
55
Is all sexual dimorphism caused by sexual selection?
No, sometimes its natural selection
56
What is altruism?
The actors suffers a cost; the recipient receives a benefit
57
What is the relationship between fitness and altruistic traits?
Y axis - fitness
X axis - Altruistic trait
Negative correlation
58
What is the equation of inclusive fitness?
Direct+indirect=inclusive
59
How might altruistic behavior evolve?
Selection might favor decreasing your own fitness if it increases the fitness of your relatives, preserving your genes
60
What conditions must be met to develop altruistic behavior?
Hamilton’s rule
Br-C>0
B - benefit to recipient
R - relatedness (0-1)
C - cost to actor
61
What are the r values for half siblings, full siblings, and cousins?
R = 1/4
R = 1/2
R = 1/8
62
Were prarie dogs more or less likely to danger call if they were with kin?
WAY more
63
Why do squirrels sometimes adopt pups?
If they are related to them in some way, it increases their indirect fitness (changes per pup they adopt)
64
What is multilevel selection?
Cooperation between individuals that are not related
If cooperators benefit their social groups, then cooperation will increase in frequency, even if it decreases in frequency within groups
65
Describe the group fitness and individual fitness of cooperators
Group fitness - increases
Individual fitness - booty, selected against
66
What are the three things needed for artificial selection?
1. Variation on a trait
2. Variation of trait must be heritable
3. You need to be able to make copies that biological system
67
What are the two strategies to replicate parent communities?
Propagule Strategy (grow two strains you want on different offspring plates) and Migrant Pool Strategy (mix the two strains you want then make offspring plates off of that one)
68
How are so many variations that are not supported by conventional variation able to come about?
Isolation by distance
69
How do sequences change over divergence time?
Linearly
70
“Rate of evolution is far too ___ to be driven by selection”
High
71
What does L equal?
1 - wbar
72
How many adaptive substitutions did Haldane believe there were per 300 generations?
1
73
What is the neutral theory?
Most changes must be neutral, main driver is genetic drift
74
What is the population size of diploid organisms?
2Ne
75
What is the neutral mutation rate? (Just a symbol)
U
76
What is the frequency of new mutation under the neutral theory?
1/2Ne
77
How many new mutations occur per generation according to neutral theory?
2Neu
78
What is the rate of substitution under neutral theory? (Replacing one allele for another)
U
79
What is most of evolution driven by according to neutral theory?
Genetic drift
80
Do different genes have different clocks?
Yeah, there is a molecular clock for different sites
81
According to neutral theory, why is there so much variation?
Mutations are on their way to fixation or disappearance, not because of balancing selection
82
What is molecular polymorphism?
Coding portion of a gene being variable within a species
83
What is molecular divergence?
A fixed genetic difference between species
84
What are problems with neutral theory?
Heterozygosity does NOT scale with Ne (the prediction would be a positive slope for neutral theory, the real one is a straight line)
Y axis - 2pq
X axis - Ne
Calendar vs generational time is different in species and doesnt take into account non protein changes
85
What does the nearly neutral theory entail?
- Small populations are driven by drift, big populations are driven by selection
- Predicts high 2pq in large populations
- Predicts an inconstant molecular clock
- If 4Nes<1, mutations are neutral, freq change stochastic
86
What does the Neutral theory look like versus the Nearly Neutral theory?
Neutral theory - a spire on Fitness 0 and a small hump for positive fitness
Nearly neutral theory - a spire on fitness 0 with a slight distribution to slightly bad and slightly good and a small hump for positive fitness
87
Since neutral theory predicts low evolution, non synonymous mutations should be ___ and synonymous mutations should be ____
Low, high
88
What is a hard sweep?
A beneficial genotype sweeps the gene pool and becomes the main one
89
What is a soft sweep?
Several adaptive mutations rise in frequency but do not overtake one another
90
Are sweeps consistent w/ neutrality?
Nope
91
Polymorphism and divergence are correlated if they are a function of the parameter ____
Neutral Mutation rate
92
If neutral is true, the S:NS ratio should be ____ within and among taxa
Equivalent
93
Are the S:NS Ratios equivalent?
Nope
94
What explains the C value paradox?
Introns
95
Things that are diploid are said to have ____
Redundancy, a back up set
96
What does being diploid allow?
To have a new functional chromosome, called neofunctionalization
97
Describe how being diploid allows fish to live in freezing temps
One chromosome has a protein synthase, the other has an anti freeze
98
What is the relationship between mutation rate and genome size for non eukarya?
Negative relationship
99
What is the relationship between mut rate and genome size in eukaryotes?
Positive
100
Life history is all about ____
Tradeoffs
101
Can you artificially increase life span?
In flies yeah
102
What are the two possible reasons organisms age and die?
Mutation accumulation and antagonistic pleiotropy
103
What is the mutation accumulation hypothesis?
Late-acting deleterious mutations are weakly suggested against because you have already reproduced
104
What is antagonistic pleiotropy?
Alleles with early benefits but later costs can be adaptive
105
Why do female birds usually lay less than optimal amounts of eggs?
Tradeoffs between offspring performance and future reproduction
106
What is genomic imprinting? Think the growth factor thing
When parents give direct resources to the embryo (ex. Male mate gives a gene that triggers more growth and female mate codes for something that inhibits said growth)
107
Why does antibiotic resistance fall when antibiotic use declines?
It’s not selected for because there is no pressure for it, therefore the cost of the resistance is too much
108
What is genomic imprinting?
Biochemical marks that can distinguish paternal and maternal alleles
109
Why do pathogens rapidly evolve resistances against antibiotics but not to vaccines?
Vaccines work pre-emptively so theres not a large enough population of the pathogen in the body to have a shot at having the mutation for resistance and vaccines target multiple protein sites so there would need to be MANY mutations to survive
110
How could one make antibiotics more vaccine-like?
Combination therapy and giving different drugs to different patients
111
What is the coincidental evolution hypothesis?
Pathogen virulence isn’t a target of selection itself
112
What is the shortsighted evolution hypothesis?
Traits that enhance pathogen fitness within hosts DECREASE transmission between hosts
113
What is the tradeoff hypothesis?
Virulence can be favored by selection is killing the host increases transmission chances
114
Which type of virus transmitters benefit from killing the host and which dont?
Vectorborne benefit, directly transmitted dont
115
What are the two host-pathogen coevolutions?
Red queen (frequency dependence) and arms race
116
Describe arms race
Parasites higher and higher infectivity
- new host resistance alleles have a fitness advantage
(Y axis - fitness, X axis - generation, with each generation having a sideways S shape)
117
Why are there species?
- discontinuous states of matter
- adaptation to discontinuous ecological niches
- reproductive isolation creates discontinuity by allowing taxa to evolve to evolve independently
118
What are some premating isolating mechanisms? What are some postmating isolation mechanisms?
Pre
- temporal and ecological
- ethnological
- mechanical
Post
- gametic/zygotic mortality
- hybrid inviability
- hybrid sterility
119
What is allopatric speciation?
animals from original same species separated by barrier and one species develops differences
120
The longer the isolation, the more the ____
Speciation
121
Do isolated groups sexually favor those from the original group or from their isolate group?
Isolated
122
In a zone of sympatry, percent of ___ increases
Hybridization
123
With species that have been separated for a long time, is there a still a chance for reproduction between them?
Yes but its very small
124
Reinforcement is a form of ____
Character displacement
125
What is reinforcement?
natural selection selects against hybridizations, furthering speciation and making the two species more isolated
126
In allopatric taxa, The more genetic difference, the more _____ isolation
Pre-zygotic
127
What is parapatric speciation?
Ranges are contiguous (share the same border) and non-overlapping, associated with steep enviro gradients or habitat boundaries, usually have some hybridization zones
128
What is peripatric speciation?
One population that splits into several isolated populations
- genetic drift via bottleneck
- new genetic environments which have different modes of selection
129
What is sympatric speciation?
Populations occupy the same space
- reproductive isolation involves assortative mating
- two locus theoretical models:
- one gene for fitness associated trait
- one gene for mate choice
- evolution of functional linkage by selection
130
What is Haldane’s Rule?
When in the F1 offspring of two different animal races one sex is absent, rare, or sterile, that sex is the heterozygous sex
131
What does speciation require if the ancestor is AABB?
A double homozygote of aa or bb
132
As genes become more different they become more _____
Isolated
133
Sympatry shows an ____ rate of speciation
Increased
134
Who shows isolation first: males or females?
Males
135
What is epistasis?
The effect of genes that are alleles on one another
136
What is the protein coded that, when evolved differently, become incompatible with other species?
Nucleoporins
137
What is a Darwin?
Change by a factor of e per million years, uses generational time because theyre off of fossils
138
What does the rate of evolution depend on?
The time interval measured
139
Does evolution happen constantly or in spurts?
Spurts
140
What are the three types of extinction?
Gradual extinction (passive replacement), mass extinction, competitive replacement
141
If you’re a sufficient species, do you have less chance of extinction?
Nope, extinction has the same likelihood no matter how long your species lives for
142
What is the McDonald Kreittman test?
The punnet square with S:NS
143
What is the on the punnet square of the McDonald Kreittman test?
Synonymous Non-synonymous
Polymorphism
Divergence
144
P and D not being equal means?
There is some selection
145
What is the relative rate neutrality test?
Ya-yb = 0 or ya=by (same rate of divergence)
Ya-yb=ao-bo
Y is the ancestor of a and b, o is the far removed relative of y
146
Do all chromosomes have equal evolution rates?
No, those around heterochromatin have really low rates
