Exam 3 ch 11-14, 16 & 20. Flashcards
(200 cards)
1
Q
What are 4 traits males and females commonly differ in?
A
Size, Coloration, Shape, and body ornamentation.
2
Q
Why is sexual dimorphism so common?
A
Due to there being variation in individuals in their success for getting mates and successfully reproducing.
3
Q
What increases an individuals reproductive success?
A
Sexual Selection.
4
Q
Why do most female species have less variation among them in comparison to males?
A
Females have a fixed max fecundity, while males fecundity is primarily based off his number of mates (more mates = more offspring.)
5
Q
What are two things about females limiting their reproductive fecundity?
A
Eggs are more energetically expensive.
Females generally have more investment in the offspring.
6
Q
What is a trade off that affects the reproductive fitness of females/ parents?
A
More invested offspring increases the offsprings fitness, however this decreases the parents remaining fitness.
7
Q
If factors limiting reproductive success are different between males and females…
A
There should be different relationships between reproductive success and number of mates.
8
Q
For most females number of mates affects their reproductive fitness how?
A
does not increase reproductive success since females are limited by their own ability to produce offspring Vs mating.
9
Q
Competition between members of the same sex & species for mates?
A
Intra-sexual selection.
10
Q
When males cannot control access to females, so they advertise to females and the female selects.
A
Inter-sexual selection.
11
Q
What are the 3 main types of intra-sexual selection? (Male Combat)
A
- Sperm Competition.
- Infanticide.
- Male-Male Combat.
- Prolonged Copulation
- “plug”
- unappealing pheromones.
12
Q
What are the two main types of sexual selection?
A
Intra and inter sexual selection.
13
Q
What are three factors that could lead to sexual dimorphism?
A
Heritability, Variation, and differential Reproductive success.
14
Q
What is the Fair raffles Vs Loaded Raffle?
A
Types of sperm competition.
Fair: More sperm.
Loaded: less, but better quality sperm.
15
Q
In species that utilize sperm competition will they always produce tons of sperm?
A
No, while sperm is cheap, it is not free. Some species have developed bodies that react to their environment and will produce more sperm when exposed to mole males (competition.)
16
Q
What are the types of sperm competition?
A
-Fair Raffle.
-Loaded Raffle.
-Prolong copulation (love bugs.)
-Copulatory Plug.
-Unappealing pheromones applies to female.
-Ability to “scoop” out previous sperm.
17
Q
What is a reason infanticide occurs in lions?
A
Since a pride coalition only last about 1-2 years and gestation is about 3-4 months the male lion is limited in the amount of litters he can father. Infanticide causes the lioness to become receptive to mating sooner than if the cubs lived and thereby increases reproductive fitness of the male lion.
18
Q
What leads to the evolution of elaborate courtship displays?
A
inter-sexual selection.
(female choice.)
19
Q
What are 4 reasons for female choosiness?
A
- Acquire good genes for offspring.
- Acquire resources from males.
- Males may be exploiting pre-existing bias in females. (think of the fish and red dot.)
- Arbitrary preference.
20
Q
In species where both the male and female put in a “good amount” of investment does sexual dimorphism still occur?
A
It can. This is due to overall reproductive success. Males that are more “attractive” (inter) will find mates quicker, and likely form extra-pair copulations leading to an increased reproductive fitness of that male.
21
Q
What is an examples involving frogs that shows evidence of female choosiness?
A
Female frogs showed a preference for long and louder calls from males. so much so they would pass by shorter male calls to go to the longer and louder male call.
It was found these males produced either equal or more fit offspring also supporting the “good genes” hypothesis.
22
Q
What is a direct benefit of female choosiness?
A
Some males attract females using food or shelter or some other resource that directly benefits the females survival.
23
Q
Females guppies show a reproductive preference towards males that have red dots on them. It was found these guppies eat a prey that is bright red and small. What is possibly causing this preference?
A
This is an example of a sensory bias. Since these fish are naturally attracted to small red shapes to obtain food this transfers over to them being more interested in red dot males as they may think they are going to obtain food.
24
Q
it is found that some female bugs mate with males that have longer eye stalks, while some females mate with short. Their offspring tend to follow the pattern. assuming the eye stalks do not affect fitness, what is this an example of?
A
This is an example of both arbitrary selection and runaway sexual selection.
Arbitrary- preference not affecting fitness.
Runaway- think positive feedback loop. Preference and outcome become linked.
25
What is diversity in sex roles mostly based on?
The relative contributions to rearing offspring.
26
A species such as pipefish/ seahorses. What is expected regarding their sexual dimorphisms.
Since males have a higher contribution and rear the offspring in a brood pouch, it is the males that is limited by how often he can brood offspring, while the female is limited by how many males she can deposit eggs into. Expect choosy males and competitive females.
27
Is there evidence for sexual selection leading to sexual dimorphism in plants?
When pollen is transported by animals, male flowers are limited by pollinators, this leads to larger and showy males flowers, while female flowers are not limited by this but by their ability to produce eggs and fruit.
28
What is protandry?
This is when all organisms are born male.
29
How do clownfish, which experience protandry, reproduce?
Due to them all being born male they can change sex. In clown fish the female is the largest and the breeding male is the next largest. There are other non-breeding males. if the female dies, the breeding male will switch sexes and breed with the next largest male.
30
Why do angler fish reproduce so that the male burrows into the female?
Since at the bottom of the ocean resources are very difficult to come by. When a female angler fish is able to produce eggs it is most effective to already have a male on standby Vs. having to go find one in such a desolate zone.
31
What is Fisher's principle?
Why?
What is an assumption of it?
The sex ration will be 1:1 in diploid populations
Due to frequency dependent selection.
Assuming equal cost to produce Males Vs. Females.
32
Does Fisher's principle mean there will always be a 1:1 ratio of sexes in diploid organisms.
No, because adult ratios may change as organisms die or are killed.
33
What is the operational sex ratio?
What does it mean to have greater bias?
The local ratio of fertile females to sexually active males at a time.
Greater bias has a higher potential for sexual selection.
34
Do humans experience inter-sexual or intra-sexual selection
There is observational evidence for both. Ancestrally intra seems to be more common.
35
Evidence for possible intra-sexual selection in humans?
males commit more same sex violence.
36
Evidence for possible inter-sexual selection in humans?
Married polish men are much taller than those who are not married. Possibly choosy females.
37
What is handicap hypothesis?
Females having preference for a trait the decreases the males fitness. This is likely due to it "proving" the male is stronger to survive with it. Think about birds with super long tail feathers- makes easier prey, yet is favored by the females.
38
What explains sexual dimorphism?
Sexual selection.
39
If sexual selection is in opposition to natural selection can it still increase an individuals fitness?
Yes since that individual will be more successful at reproducing.
40
Fitness gains for both partners?
Cooperation.
41
Fitness gain for recipient, cost for actor?
Altruism, Doesn't really happen in nature.
42
Actor Gains, Recipient loss.
Selfishness. (Most Common interaction.)
43
Fitness loss for both partners.
Spite.
44
What is evidence for cooperation?
Birds that have nesting coalitions have higher overall fitness in the males and females even though the first females gets her eggs tossed out of the nest.
45
What is evidence for selfishness?
Toads eating tadpole eggs, hurts fitness of the eggs and who produced the eggs, but directly benefits the frogs fitness.
46
What is evidence for spite?
There are bacteria that produce toxic compounds, these are costly to produce and also negatively affect other bacteria.
47
When witnessing perceived altruism in nature what may actually be going on?
While the individual seems to have their own cost to benefitting others this is usually due to relatedness to other organisms therefore indirectly increasing the actors inclusive fitness.
48
What about ground squirrels signifies perceived altruism?
What is this also called?
The squirrels call out when predators are nearby, putting themselves at risk of being caught. However it was found the females usually do the call and the by relatedness the other female family members would help chase off predators.
This is an example of kin selection.
49
What was a special difficulty for Darwins theory of selection?
Altruism.
50
What are four evolutionary explanations for perceived altruism?
- Kin Selection.
- Reciprocity.
- Mutualism.
- Manipulation.
51
What is Hamiltons Rule?
A rule describing the likelihood of "altruistic" genes persisting. It states that B*r-C > 0 to persist.
52
Explain:
B*r-C > 0
B - Benefit to recipient.
r - Coefficient of relationship.
C - Cost to actor.
Must be greater than 0 or "altruism" will not persist.
52
Direct + indirect fitness?
Inclusive fitness.
Direct- personal reproduction.
Indirect- Genes passed on through familial reproduction due to help given by relatives.
53
What conditions lead to kin selection?
When natural selection favors alleles that increase indirect fitness, kin selection will occur.
54
What are the relations from actor to parent, sibling, half sibling, neph, niece, grand child, cousin, great grandchild?
Parental: 1/2
Sibling: 1/2
Half sib/ neph/niece/ Grand Child: 1/4
Cousins/ Great Grand child: 1/8
55
What is the evidence for kin selection?
Kin selection is shown in squirrels and the likelihood of them adopting orphaned baby squirrels. The closer the relationship the more likely the orphans will be taken in also the less cost = more likely.
56
When kin selection is between sibling and children r=0.5 what is likely to occur?
The children will be selected since they likely have a higher fecundity and therefore will have a higher indirect benefit to the actor (Parent.)
57
An actor exhibits "Altruism" to an unrelated recipient. The recipient is the same species. what are the possibilities that could be occurring?
assuming the two share similar phenotypes what is most likely occurring?
Possibilities:
Mutualism.
Reciprocity.
Manipulation.
Most likely this is a type of kin selection: "green beard" effect where "altruistic" genes are selected with a certain trait that continues the lineage of that trait regardless of relation. ie: Selfish Gene Model.
58
What is the evidence for green beard effect?
There is a species of slime mold which has a trait that allows them to stick together better with other molds that have the same trait. When grown in their natural environment and starved they will come together to make a stalk and spores to go out and spread. In soil this is mostly the "sticky" mold because they can pull towards each other and work together much better than the mold without the "sticky" trait.
59
What are the two types of parent-offspring conflicts in kin selection?
Weaning conflict.
Siblicide.
60
Young demand milk at the start of nursing, since they are small this is little cost to the parent and great benefit to the offspring, what is expected as time goes on?
The offspring will become larger and start to demand more milk, more cost from parent. The benefit to young is decreased as the young can find their own food. Mothers will stop producing milk when this ratio reaches 1.
61
Species of birds have shown "altruistic" behavior by helping raise their siblings Vs. Starting their own nest. Why? what is this an example of?
This is an example of parent-offspring conflict. The reason these birds help raise their siblings is because the father harasses their sons into helping by disrupting courtship and territory. limited breeding opportunities. Helping the sibling has about the same indirect fitness benefit as own clutch.
62
Certain birds help raise their siblings because the father harasses their sons into helping by disrupting courtship and territory. Why do the sons give in to this?
This is because the sons share the same r for siblings and offspring: 0.5 and they have similar fitness benefits to the sons that help raise their siblings Vs. their own clutch.
This usually occurs when breeding opportunities are limited.
63
What is the evidence for siblicide?
In certain birds that lay more than one egg the first hatchling may push the other egg out of the nest. This is likely because individual r=1, sibling=0.5. So they do this to help their own chances of survival, especially when there is long-term food shortage. in short term they may eat less to benefit the sibling, up until the total benefit is 0.
64
Why do or don't parents intervene in siblicide?
In some species the parents to intervene to increase their overall reproductive success in others they don't, this may be due to having more eggs than can be cared for as an "insurance" incase the first one is a dud. Truly the reason is unknown why some do and some don't.
65
Cooperation among individuals due to the favor being returned.
Reciprocal altruism.
66
What are the 5.5 requirements for reciprocal altruism?
-Cost must be less or equal to recipient benefit.
-Cheater must be punished.
-Repeated interactions W/ memory.
-The altruists are each on symmetrical "grounds" no social hierarchy.
-The benefits to each recipient are equal.
67
A species which is long lived, intelligent, social in small groups with low dispersal rates and mutual dependence in activities might exhibit which type of altruism?
Reciprocal Altruism.
68
What makes reciprocal altruism less likely to occur?
Dominance hierarchies.
69
A strategy that if most players adopt will lead to the most production and cannot be bettered.
An evolutionarily stable strategy.
70
What is the evidence for reciprocal altruism?
In vampire bats they die if they do not have blood for 3 days. they have small group sizes and live up to 20 yrs. Bats able to get enough blood will re-gurge and share accordingly based on relatedness and association in hopes of returned favor in the future.
71
A bird is raising an egg that it did not produce. Why is this altruism taking place?
This is not true altruism, this is likely manipulation. Birds have evolved to raise the eggs in their nests and it probably doesn't realize that isn't it's egg.
72
An interaction in which both parties directly benefit by either survival and reproductive success.
No time lag in between benefits.
Mutualism.
73
There is a species of ant that lives on a tree. The tree provides food and shelter while the ants provide protection from competing vines & insects. What is this an example of?
Mutualism.
74
There is a social system that has an overlap in generations, cooperative brood care, and castes of non-reproductive individuals.
What is this?
Eusociality.
75
What are the two taxonomic groups which exhibit eusociality?
Which is more extreme?
Naked Mole Rats and the more extreme Hymenoptera.
76
What is the haplo-diploidy hypothesis?
This is meant to explain why eusocial systems might form.
in haplo-diploidy (Diploid) sister r=0.75 and (haploid) Brother r=0.25 to workers. Female ants should show altruism towards their more closely related sisters.
77
What is the evidence for Haplo-Diploidy Hypothesis?
In haplo-diploidy (Diploid) sister r=0.75 and (haploid) Brother r=0.25 to workers. Due to this we expect a 3:1 sex ratio. It is shown queen ants produce 1:1 ratio (same r factor to m & f offspring.) the worked ants selectively kill the male eggs to control sex ratio.
78
What is the evidence against Haplo-Diploidy Hypothesis?
Eusocial organisms that are not haplo-diploid such as naked mole rats exist and exhibit eusociality.
Queen ants mate multiple times/ sometimes multiple queens means much lower r, and no loner follows Hamilton's rule.
79
What is favored when it is easier to become a "helper" Vs reproducing?
Eusociality.
80
What does phylogeny suggest about eusociality?
That it is favored more by the ecosystem Vs genes. This is due to "best of a bad situation" hypothesis: Building complex nest and larvae care is not possible for a lone female and there may be greater benefits to being a helper Vs. going on own.
81
What are the benefits to helpers in the wasps polistes?
What kind of eusociality do they exhibit?
Indirect fitness benefits since they likely share a relation to the foundress.
Direct benefits if the foundress dies and the female wasp gets to take over.
Costs and benefits depend on female body size r coefficient.
The exhibit Facultative eusociality since the workers are not sterile.
82
Why are naked mole rats eusocial although they are not haplodiploid?
This is likely due to environmental and genetic conditions.
Naked mole rats do not survive well on their own and since they stay in their groups they have a high Fis and r=0.81 meaning workers are more related to siblings than offspring.
83
mole rats have a very high r=0.81 between workers and siblings. Why is there worker conflict observed in mole rats?
Since there are 3-4 breeding males there are the presence of half siblings which have lower r than offspring. Queens maintain control by their large size and will shove slower workers and is usually directed towards more distant relatives.
84
Does true altruism exist in nature?
NO.
85
The branch of evolutionary biology that attempts to sort out reproductive strategies.
Life history analysis.
86
What is a Darwinian Demon?
The "perfect" evolutionary organism which would be mature at birth, produce many quality offspring, and live forever.
87
Why don't Darwinian Demons exist?
Because there are trade offs in time, size of offspring, and parental investment. ie. Organisms have a limited energy budget.
88
What are two examples of extreme life history reproductive strategies?
-Thrisp mites are born already inseminated by siblings and eat their way out of the mother when she is 4 days old.
-Kiwi's produce eggs 1/6 their body weight, but the chicks our on their own within a week, takes 1 month per egg.
89
Why is there life history variation?
Because there is variation in the environment, this can lead to trade offs such as when to reproduce, waiting means more sufficient/ larger offspring, but higher chance of dying before reproducing.
90
How many offspring should an individual produce in a year?
Organisms will produce offspring in a way that optimizes maximum lifetime reproduction
91
What does is mean when there are differences in life history?
Then there are differences in energy allocation.
92
Some female opossums have litters earlier than others and spend less time of growth. What does this indicate?
They have different life histories, and therefore different energy allocations. It is likely the earlier producing possum will have smaller offspring that may have a smaller chance of survival, but she also may have more as a trade off between size. If both possums were to die early she would have a higher fitness.
93
What is evidence for life history trade off?
in sand crickets some have short wings and others have long wings. shorter wings devote more energy to reproduction, while long wing devote more to flight. The trade off is between ability to fly to other resources and having more offspring.
in low resource areas long wings are higher fitness, but not in resource rich areas.
94
Late life decline in fertility and survival?
Senescence.
95
What do expect regarding fitness of senescence?
We expect it to be selected against since it directly harms reproductive fitness.
96
What are the two hypothesis for why aging persists
- Rate-of-living hypothesis.
- Evolutionary Hypothesis of aging
97
What is the rate of living hypothesis?
A hypothesis that Senescence is caused by irreparable damage from errors in replication transcription, translation, and accumulation of poisonous metabolic by products.
It states that all organisms have been selected to resist and repair as much as possible and have reached a limit.
98
What is the support for rate of living hypothesis?
When the rate of living is focused on a cellular level life span of RBC's and skin cells (chromosomes) it is found this does correlate with the life span of the animal.
99
What are the two predictions of rate of living hypothesis?
-Since damage is caused by metabolic processes aging rate should be related to metabolic rate.
-later refuted to only be supported on cellular level life span of RBC's and skin cells (chromosomes).
-Since organisms have been selected to repair max possible species should not be able to evolve longer lifespans. Possibly due to trade off's between extending life and cancer.
100
What is evidence against Rate of Living hypothesis?
Drosophila was able to be selected for a longer lifespan.
Great variation in energy expenditure per gram of tissue in different species.
101
What is the Evolutionary hypothesis of aging?
- Aging is caused by the failure to repair cellular damage due to deleterious mutations or trade-offs between repair and reproduction energy use.
-Deleterious mutations accrue and affect individuals late in life/ only slightly affecting reproductive fitness, same for late life cancers.
-these factors cause death with little affect to individuals fitness.
102
What is support for evolutionary hypothesis of aging?
it was shown if a deleterious allele causes an earlier death but does not strongly affect the reproductive success of the organism then the selection against it is weak, as the organism has already reached if max lifetime reproductive success by the time it dies.
103
What are antagonistic pleiotropic effects?
The productions of two or more effects by a gene that work against each other. One is beneficial to the organisms while the other is not. if the benefits outweigh the negative it will be selected for, this is why aging may not just be neutral, but actively selected for.
104
Why might antagonistic pleiotropic effect be selected for?
If the "benefit effect" has a greater fitness weight than the "negative effect" the pleiotropic gene will be selected for. This could be something such as a trade off between early reproduction and survival later in life.
105
What are the two key factors of the evolutionary hypothesis of aging?
- Reproduction happening earlier in life so that death is not selected against.
- Mutation devotes less time to repair and more time to reproduction.
106
Support for evolutionary hypothesis of aging trade offs?
Flycatcher birds are shown to be polymorphic in maturation/ reproductive age at 1 or 2 yrs old. earlier breeders have smaller clutch sizes and yet still had higher lifetime reproductive success.
107
How does the evolutionary hypothesis of aging explain the different lengths of lifespans?
High adult mortality should produce earlier maturation.
In opossums it was shown that on the mainland with higher adult mortality rates they had earlier deaths and maturation. On the island they lack predation, so they evolved delayed senescence.
108
What is the best explanation of life history variation?
The evolutionary hypothesis of senescence/ aging.
109
Why does menopause exist?
Possible evolutionary artifact, grandmother hypothesis that those in menopause can help family and continue to increase their own indirect fitness. May also be due to trade-offs regarding quality of offspring/ organism surviving reproducing at a later age Vs. caring for indirect fitness.
110
How many and how big should offspring be produced?
Selection will favor amount and size that leads to the highest survival of offspring. EX: as more eggs are added the less the parents can invest individually, to a point it decreases that offsprings survival.
111
What is the support for not producing the max number of offspring whenever possible?
even if they all survive why is it still selected against?
In birds when too many eggs are added to the nest the offspring fitness decreases and less survive, if they do all live: less resources are put into each chick & this still leads to a decrease in the chicks fecundity/ fitness thereby decreasing the parents indirect fitness as well.
There is also observed trade offs between clutch size and future reproductive effort.
found some Birds can predict environmental condition there is plasticity affecting clutch sizes.
112
What are the three assumptions of Lack hypothesis?
1. No trade off between parental reproductive effort and survival in the future.
2. The only effect of clutch size on offspring is determining whether offspring survive.
3. Clutch # & size is fixed by a particular genotype.
All of these have evidence proving them incorrect.
1- There are proven trade offs.
2- Offspring reproduction affects parent indirect fitness.
3- There is demonstrated phenotypic plasticity in clutch size, and this can be adjusted if the birds predict good or bad environmental conditions.
113
What is valuable about Lacks hypothesis?
Serves as a good null hypothesis for expected like HWE sorta.
114
What is an example of how lacks hypothesis may be used?
In parasitic wasps they calculated "Lacks" ideal clutch size, it was then found wasps produce smaller than expected sizes. This is likely due to some kind of trade off affecting the females future reproduction or survival fitness. ie. Larger clutches might decrease the females fitness in some way. found that larger clutches don't contribute to fitness as much as just laying a smaller clutch and finding another host faster.
115
If Lacks hypothesis is violated what does that mean?
This means there is evidence of some kind of trade off.
116
How big should offspring be?
There are trade off in energy for size of offspring and the amount of offspring produced. offspring size correlates to their survival.
117
What is the conflict between parent and offspring affecting size?
Bigger offspring have better survival.
Bigger offspring are more costly to parent who wants to ration between all current and future offspring.
118
Is Smith and Fretwell's hypothesis regarding offspring size always applicable?
Only applicable when there is high polymorphism in offspring size in a population.
119
What is the evidence that larger offspring have better survival and that the there is trade off between parent fitness and offspring survival?
In certain beetles they were tested for laying their eggs on a good Vs. poor host. It was observed that the eggs on the poor host were larger than eggs on the good host, this helped equal the fitness of all the offspring, and shows phenotypic plasticity in egg size.
(experimentally shown that small eggs on poor hosts mostly died, while larger eggs on good host thrived.)
120
What is a reproductive conflict of males and females?
Females have r=0.5 for all offspring so equal care, while males (unless monogamous) do not have r=0.5 to all off spring and want resources spent on his offspring.
This is affected by genomic imprinting which causes a difference in how resources are spread to placentas. Father imprinting more resources, mother imprinting tug of of war to even out the resources.
121
What is a down side to a small clutch size as parents increase in size even though they will have larger offspring with higher chance of survival?
This puts the species at a higher risk of extinction due to having less offspring so if they do die this is a huge loss of fitness. Vs losing one of a large clutch size.
122
What is the study of incidence, frequency, distribution, and control of infectious diseases in defined populations?
Epidemiology.
123
What is the germ theory of disease?
One of the most important breakthroughs in modern medicine. Discovered that diseases don't randomly occur and instead are caused by GERMS.
This led to use of antiseptic techniques, antibiotics, and identification of pathogens.
Common sense saved lives on that day.
124
Does human imposed selection lead to an evolutionary response in pathogens? Evidence?
YES! We are in a constant "Arms-Race" with viruses and bacteria. Flu strains with novel mutated antigenic sites show favored selection Vs mutations in non Antigenic sites survival.
125
Specific regions on the surface proteins of viruses that are recognized by the hosts immune system.
Antigenic sites.
126
What are Neuraminidase and Hemagglutinin?
Names for some of the surface proteins found on influenza virus and are commonly used to describe different strains. Dog influenza is commonly H3N8 and H3N2. The numbers refer to the mutation subtypes.
127
Flu exhibits mutations selected for in primarily in antigenic sites due to the human immune response. What can be said about the surviving flu viruses?
The survivor will be be the ancestor to future flu strains and is also most likely to be the most different in H
(Most substitutions in 18 codons of the hemagglutinin protein antigenic site.)
128
What is the Role of hemagglutinin in influenza?
Initiates the infection, when this differs the virus should have a higher infection rate as the immune system does not recognize it yet.
129
Chemicals which kill bacteria via interrupting their biochemical processes.
Antibiotics.
129
How is the flu able to have closely related genes and also distantly related genes. For example human flu picking up bird flu characteristics?
The flu virus is able to trade genes with other flu viruses. There is some flexibility in the species flu can infect EX: bird flu sometimes infect pigs. it is thought that there must be instances where an organism catches both flu's and that is when the flu's are able to trade for novel genes. Which may even allow them to swap hosts entirely.
130
What is the evidence for antibiotics being a strong selective force?
A large scale observational study tracking antibiotic use and resistance found that seasonally as more antibiotics are prescribed in the coming months there are more cases of antibiotic resistance reported. There is an implied trade off with resistance and fitness in bacteria as the resistance lowers once antibiotic use has gone down. implying higher fitness of non-resistant bacteria without the presence of antibiotics.
This is not true of all bacteria though.
131
What is our best defense against antibiotic resistance.
- Avoid the need for antibiotics (avoid things that could lead to bacterial infection.)
- Don't use antibiotics for viruses.
- Complete full course of antibiotics.
- Prescribe narrow range antibiotics
- Isolate patients with resistant strains.
- if minor infection on relatively healthy patient maybe just provide supportive care and allow the body to do it's thang.
132
What is Virulence?
The ability for a virus to cause damage to it's host.
High virulence = High mortality
133
What are the 4 hypothesis that explain changes in virulence?
- Evolution of benignness (recent Entrance.) -low support.
- Coincidental Evolution hypothesis.
- Short sighted Evolution Hypothesis.
- Trade-off Hypothesis (Transmission rate.)
134
What is the evolution to benignness hypothesis?
Evidence for or against?
(Recent entrance.) Contends that pathogens are only highly virulent when first infecting new species host and overtime evolve to benignness.
(Perfect pathogen should not kill its host usually in theory)
NOT MUCH SUPPORT.
Conflicts with evidence from rate of transmission.
New pathogens are found to not be highly virulent usually since they are in a new host they are not adapted to yet.
135
What is the Coincidental Evolution hypothesis Theory?
Evidence for or against?
Some Pathogens that are of non-human origin and have not evolved with humans coincidentally infect humans.
This does occur ie: Tetanus, legionnaires disease, However this is not common and is more the exception Vs. the Rule.
136
What is the Shortsighted Evolution hypothesis?
Evidence for or against?
This implies that when pathogens reproduce within a host, short term fitness benefits may be selected for even if they lead to long term detriments. If high fitness = virulence this will be beneficial in short term but will kill of host before being passed on.
Evidence is Polio which usually infect digestive tract occasionally infects the nervous system, the short term affect is more offspring and virulence, however this has tragic consequences and the host will likely die before passing it on.
137
What is the Trade off hypothesis of virulence?
Transmission rate hypothesis states viruses will evolve to the optimal virulence based on the rate of transmission. Transmission High? = Virulence high since it will be transferred quickly.
Viruses have a trade off between virulence and infection duration/ possible transmission
138
If a pathogen is difficult to transmit what is expected evolutionarily?
A lower virulence, otherwise the host may die before transmitting the virus.
This is in line with Trade-off hypothesis.
Supported by evidence from E.coli (high scientific artificial transmission, higher virulence.)
and HIV.
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What is expected of virulence in regards to vectors and direct transmission?
Direct transmission is likely to evolve less virulence because if it's host dies too fast it will not be transmitted. However a vector is expected to have higher virulence since the vector is able to continue to reinfect regardless of virulence.
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Why has the flu had what seems to be an up and down virulence?
The flu is direct transmission virus, nowadays people are more careful about spreading thier sickness which will likely lead to a less virulent flu, however when WW1 was going on, there was constant close contact between soldiers and if one died due to virulence, they got replaced leading to a great transmission ground therefore high virulence that got release to the public.
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What is example of selection imposed by lifestyle in a population?
In humans we produce lactase when we our young to digest mothers milk, once we begin to eat regular food there should be no more advantage to reproducing this gene, however western lifestyle involves a lot of dairy and favors the continued production of lactase in adults.
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What are the two theories regarding why some organisms get a fever when they contract a pathogen?
* Immune response theory: possible host immune system does better in higher temp?
* Pathogen-inhibiting theory: Adaptive defense by host to kill pathogen. (Most likely)
Manipulated temps in infected iguanas and found fever to have more host % survival.
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If fever is an adaptive mechanisms against pathogens should you take fever reducing drugs?
Fever is also not ideal to human metabolism/ homeostasis- depends on length and severity of fever.
if mild and short in suspected low-intermediate grade pathogen may just be best to let fever/ immune system do it's thing with other types of supportive care like fluids etc.
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Why are humans hard to study?
We are often exempt from natural selection, we can perform altruism or spite with little to no cost. likely evolved from natural selection on ancestors.
"We are not exempt from the selection we are causing on ourselves through human worldly impacts"
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What is examined in testing the hypothesis regarding human evolution?
Physical, Morphological, molecular, and behavioral evidence.
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What is the difference between old and new world monkeys?
Old world monkeys originated from Africa, Europe and Asia (older established continents.) and they have non-prehensile tails.
New world monkeys originate from the Americas (later established.) and have prehensile tails (meaning they can grab things with it.)
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An ancestral organism more closely related to homo sapiens than to other apes.
Hominins.
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What are our closest living relatives?
Orangutang, chimps, gorillas.
Chimps are the closest living relative. We last shared ancestry 6-7 million yrs ago.
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What clade do humans belong to?
The same clade as African great apes.
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What is a synapomorphy?
A common trait in two or more taxa that is derived from a common ancestor.
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What is the evidence for chimps being our closest living relatives?
- An outlier ancestor shares many traits with gorillas but not with chimps and humans. -Parsimony for chimps and humans to be sister species.
- when 14 independent genes were tracked this showed most congruence between humans and chimps. (least % divergence.)
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Parsimony?
The KISS method of building trees.
simplest is probably most accurate.
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How can we predict when humans and chimps diverged from a common ancestor?
Based on molecular dating techniques/ rate of change in multiple protein sequences.
154
What is the oldest known hominid fossil?
Sahelanthropus tchadensis.
Had knuckle walking adaptations still.
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What is the earliest hominid with bipedal tendencies?
Australopithecines.
(come in robust and gracile-(Lucy) more similar to modern humans)
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What was the first homo ancestor?
H. Habilis. Larger brain case, smaller teeth, taller, less sexual dimorphism.
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First human ancestor to leave Africa?
H. Erectus.
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When did modern Homo sapiens first appear?
About 100,00 yrs ago.
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Have human species ever coexisted?
Yes, as many as 5 may have existed at one time.
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What are the three hypothesis regarding the transition from H. Erectus to H. Ergastor to H. sapien?
- African Replacement Theory.
- Multiregional Evolution.
- Hybridization and assimilation. (Middle Road theory.)
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What is African replacement theory?
Theory stating H. Sapiens evolved in Africa, migrated to Europe & Asia and replaced H. Erectus and H. Neanderthalensis without any interbreeding.
Began 200,000 yrs ago.
PROS
-mt DNA supports (non african clade is nested in african clade.) however mt DNA is not the most accurate.
-30 nuclear loci showed split from african to non about 75,000-287,000 yrs ago.
African populations show more allelic diversity.
CONS
- Suspect need for advanced tool to over come H. Erectus- Tools not found.
- Australian aborigines resemble H. Erectus- indicating inbreeding.
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What is Multi-regional Evolution Theory?
States H. Sapiens evolved concurrently in Europe, Africa, and Asia with sufficient gene flow to maintain continuity as a single species, therefore current gene pools should be a mixture of all regional variants.
Began 1.8 million years ago.
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What is Hybridization and assimilation. (Middle Road theory.)?
States H. Sapiens evolved in Africa and migrated to Europe & Asia with some amount of hybridization.
This would show some European and Asian Genes persisting into modern humans.
PROs
"leaky-replacement" SNP study showed moderns humans contain some neanderthal and denisova DNA, likely happened at secondary contact.
Most Realistic hypothesis.
## Footnote
SNP: Single Nucleotide Polymorphisms.
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What were two difficulties outlining figuring out African replacement Vs. Multi-regional Evolution?
Same end result predication, only different time scales. Multiregional= 1.8 million yrs ago, African replacement= 200,000 yrs ago.
Quantitative differences.
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What are 4 uniquely human traits?
Brain size, Bipedalism, Language, and complex tools.
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Order of important hominids oldest to most modern:
1. Tchadensis. -earliest hominid.
2. Australopithecines (Gracile and Robust.) 1st bipedal Hominid
3. H. habilis 1st Homo.
4. H. Erectus 1st H out of Africa.
5. H. Ergastor "middle man"
6. H. Sapiens. "Modern humans.
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Which hominid first used language?
Likely evolved up to 2 million yrs ago. Neanderthals show a very similar hyoid bone to modern humans, but brains got bigger over time, but still has similar structure with other hominids. We know 40,000 yrs ago boats were built to travel oceans- could this have been done without language?
168
What is H. Floresiensis?
an early island based (new guinea area.) H. species. They were smaller than usual humans. it was found H. Erectus lived on a nearby island 1.6 m.y.a. and the Flores may be their descendants. Larger mammals to island tend to get smaller. They persisted until 12,000 yrs ago until a volcano took them out. But they lived at the same times as modern H. sapiens colonized nearby. (Start of agricultural Revolution.)
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What are the processes that cause macroevolution?
Mutation, Natural selection, genetic drift and migration.
Just over longer timescale.
170
O.G. Ancestor Species of all organisms?
Dates back to about 3.8 billion years ago.
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What is the most common way to differentiate species among non-scientists?
Morphological Species concept.
Based on apparent similarity "seen similarities"
Not super accurate.
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How does speciation apply to organisms?
It must have objective rules that can be applied across all organisms.
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Theoretical definition of what constitutes a species?
Species Concept.
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Practical manner in which to determine what is a species?
Species Criterion.
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What is the best evidence against special creation?
Gray areas in between speciation.
176
What is the biological species concept?
- Species defined as freely breeding population.
- Must be reproductively Isolated. (not applicable to asexuals.)
(not much explanation for hybrids and isolation by distance.)
Used by Endangered species act.
most accepted even though it requires subjects judgements.
(could show that A & E could be same species if there is gene flow when in reality they are very different.)
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What is the Morphological Species Concept?
Based on the Morphological similarities.
Difficulties:
Where is the difference line drawn?
Sexual dimorphism?
Polymorphs
Cryptic species (look alike but are genetically different species.)
Used mostly by laymen, non-scientists.
178
Phylogenetic Species Concept?
Based on phylogenetic tree where patterns of descent can be seen.
Monophyly Criterion
Cons:
Many different clades can be considered monophyletic.
Most taxa do not have phylogenies.
Currently there are many non-monophyletic species.
Very high number of species.
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Evolutionary Species concept?
- Can be applied to all sexualities.
- Based on how a lineage changes over time.
- If lineage is distinct and stable over time, it is a species.
CONS:
How to determine when species start and end?
180
Ecological Species Concept?
Species are define by occupying different adaptive zones and evolving separately.
181
Recognition Species concept?
Species specific mate recognition.
182
Cohesion Species Concept?
Focuses of mechanisms that maintain genetic and phenotypic identity.
183
What are the 7 species concepts?
- Biological Species concept
- Morphological Species concept
- Evolutionary Species concept.
- Phylogenetic Species concept
- Ecological Species Concept
- Recognition Species Concept
- Cohesion Species Concept.
- The general Species Concept.
184
What are the mechanisms of speciation?
1. Population Isolation (usually physical.)
2. Divergence of Phenotypes and genotypes.
3. Reproductive Isolation.
185
What do all the species concepts agree on?
Restricted gene flow of s species.
186
General Lineage Species Concept?
Attempts to fit together all of the species concepts, expected to replace them but has not happened yet.
Species concepts are good framework for hypothesis, but none are perfect and they are not mutually exclusive- they exhibit overlap.
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Most common speciation, most evidence.
Populations become separated by a physical barrier diverge.
Exhibits Vicariance.
What is evidence?
Allopatric Speciation.
Vicariance is when a barrier to gene flow arises.
Regions with more physical barriers tend to have more species than without.
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Speciation when genetic drift occurs usually due to founder effect and causes allele frequencies to change. Selection then acts and causes divergence. Usually geographic isolation though dispersal.
Evidence?
Peripatric speciation.
May also be helped by differences in ecological selection.
Founder fruits flies have diverged on Hawaiian island from west to east as the islands rose up. Able to use mtDNA to find phylogeny which supported this theory.
Marine fish that got into freshwater became fresh water species and occupied different layers.
189
A population is distributed across an ecological gradient. What is likely to occur?
Evidence?
Parapatric Speciation (parallel)
Must have strong divergent selection greater than gene flow, usually forms a hybrid zone.
190
You observe two species that have a hybrid zone, what is happening?
Parapatric speciation or secondary contact between previously separated allopatric species.
191
You observe a species exhibit isolation within themselves due to mutations.
Sympatric Speciation.
Disruptive Selection
Speciating by occupying different ecological niches. Hawthorne maggot flies and apple flies.
Apple flies became invasive with non native apple trees and then speciated to also occupy Hawthorne trees (Hawthorne maggot flies.) these trees have different fruiting times which led to eventual Mutation, drift, and selection pressure to isolate the species.
192
What are pre and post zygotic barriers?
Pre- barriers to mating such as snails that can only mate with like - handedness. once a sinistral mutation occurred they become reproductively isolated from the righties.
Post zygotic is when a the zygote fails or something else occurs after mating that leads to miscarriage or low hybrid viability/ sterility.
193
What acts on populations after a barrier has been formed?
Selection and drift and start to cause divergence.
Drift is bigger factor in smaller populations.
194
Why are species much more likely to develop pre-zygotic barriers?
So that species do not waste energy/ resources on unfruitful mating. individuals that cannot select for like species will have lower reproductive fitness and be selected against.
195
When do we expect to see or not see pre zygotic barriers in secondary contact?
in secondary contact of allopatric species there is likely to be more hybridization since they never had to evolve mechanisms to determine "like" from "other".
Where Sympatric speciation has already formed such pre-zygotic barriers when they speciated.
196
Selection that reduces frequency of hybrids?
Reinforcement selection.
This completes reproductive isolation
197
What happens if a hybrid is favored by selection?
It may have it's own species event, or in extreme cases homogenize the only two species into all hybrid species.
If only favored in one zone though it will just lead to a hybrid zone with possible speciation within it.
Sage bushes provide evidence, they are distributed from mountains and basins (different species) and have a "mid-ground" hybrid that is favored in "mid-ground" zones.
198
Which sex is usually sterile if only one sterile in hybrids? Rule?
The heterogametic sex. Xy males or ZW females- Haldane's Rule.
