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2B - Genetics & Evolution > week 8 > Flashcards

week 8 Flashcards

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Biology 101 flashcards
1
Q

Why do we get conflict?

A
  1. difference in investment gamete of male and female parents
  2. investment required in offspring success
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2
Q

Describe the trade off involved in investment in offspring

A
  • investment in offspring is traded off with increase in investment and decrease in mating opportunities as they invest more in offspring
  • parents are trying ti balance this offspring success with their loss of mating opportunties
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3
Q

Females benefit most when:

A
  • they can produce offspring with the best quality male
  • they get the greatest investment from male
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4
Q

males benefit most when:

A
  • females invest in his offspirng instead of other males
  • invest in current reproduction instead of future reproduction
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5
Q

What are some other investments?

A
  • providing care for offspring
  • time not able to mate
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6
Q

investing in current offspring reduces mating opportunities for___more than for ___

A

males, females

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7
Q

Describe the parent-offspring conflict

A
  • offspring wants to extract as many resources as they can from parent (maximise recruitment of resurces)
  • parent wants to limit to increase mating opportunity to invest in future offspring
  • direct sibling has r=0.5, one offspring might benefit more by monopolising resource from parent than sharing them
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8
Q

Describe the genetic conflict

A
  • paternal DNA = ‘this is my only shot’
  • maternal DNA = shared with any other offspring, limit thr amount of resource extracted so theres some left for future efforts
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9
Q

Explain how insulin-like GF and igf2r receptor interplays?

A
  1. insulin-like growth factor → individuals extracting more resource and getting larger (expressed in paternal DNA but not maternal DNA)
  2. igf2r receptor. if activated it binds onto insulin-like growth factor and inhibits it
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10
Q

What is inter-loci sexual conflict

A

evolutionary conflict between sexes, where the male and females traits that interact are controlled by different loci

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11
Q

Explain inter-loci sexual conflict and what it leads to

A
  • males evolve a strategy/physiology/morphology that increases reproductive success which is controlled by one locus
  • this creates selective pressure on females which evolve resistance and is controlled by a different loci
  • leads to ‘arms race’ between the sexes - referred to as ‘chase-away’ sexual selection
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12
Q

What are the three selective advantages male genes can cause in Drosophila females?

A
  1. Use his sperm instead of competitors.
  2. Produce more and better eggs immediately after mating.
  3. Reduce mating by decreasing female receptivity and attractiveness.
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12
Q

What is “mate manipulation” in Drosophila males?

A

Males transfer a toxic protein compound to females during mating to:

Maximize offspring production.
Decrease female longevity, reducing her chances of mating with other males.

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13
Q

What experiment was conducted to study male influence on Drosophila reproduction?

A

Male genitalia were microauterized to make them unable to transfer material during mating.

In populations where this was not done, females had lower survival rates.
Reproduction was found to decrease female longevity.

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14
Q

How does male-driven reproductive manipulation contribute to speciation?

A

Populations split, and feedback loops drive different female defenses.
These differences prevent interbreeding, leading to new species.

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15
Q

What is intra-locus sexual conflict

A

evolutionary conflict between sexes, where the male and female traits has a different optima controlled by the same locus

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16
Q

give an example of intra loci sexual conflict

A

in a species of fish, - males want bright colours - attractive to females but more obvious to predators
- females dont want bright colours - provides them no advantage

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17
Q

What is intra-locus sexual antagonism?

A

A genetic conflict where the same genes have opposite effects on fitness in males and females, leading to a “tug-of-war” rather than an evolutionary arms race.

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18
Q

What evolutionary dynamic does intra-locus sexual antagonism represent?

A

A “tug-of-war” where male and female optimal traits conflict, preventing one sex from fully optimizing fitness without disadvantaging the other.

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19
Q

What is required for intra-locus sexual conflict to occur?

A

Alleles must have contrasting fitness effects in males and females.
An allele beneficial to one sex is harmful to the other.

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20
Q

How is sexual antagonism expressed mathematically?

A

A1: Perfect female allele.
A2: Perfect male allele (e.g., brightly colored).
A1A2 in females: Fitness cost is t.
A1A1 in males: Fitness cost is s

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21
Q

What role does dominance (h) play in intra-locus sexual conflict?

A

h determines the dominance status of alleles, influencing how much of the fitness cost (t) is expressed when a female inherits A1A2.

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22
Q

What happens to a male inheriting A1A1 alleles?

A

Male fitness decreases by s due to inheriting traits optimized for female fitness, not male-specific traits like coloration or competitiveness.

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23
Q

What is the pseudo-autosomal region (PAR)?

A

A region on the sex chromosomes (X and Y) that allows homologous recombination (crossing over) during meiosis.

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24
Q

What happens if a locus is located on the pseudo-autosomal region?

A

It can cross over between X and Y chromosomes, facilitating genetic exchange

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25
Q

What happens if a locus is NOT on the pseudo-autosomal region of the male chromosome?

A

It cannot undergo crossing over with the X chromosome.
Over time, this contributes to the shrinkage of the Y chromosome.

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26
Q

Why do organisms cooperate despite it being potentially harmful to themselves?

A

Benefit others (altruism).
Serve the individual’s long-term self-interest (collective self-interest).
Lead to mutual benefits through reciprocity.
Be advantageous for related individuals through kin selection.

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27
Q

What is reciprocal altruism?

A

Cooperation with the expectation that the act will be repaid in the future, creating mutual benefits.

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28
Q

What is group selection, and why is it problematic?

A

Group selection: Acts benefiting the group rather than the individual.

Problems:
- Resource limitation restricts group growth.
- Dominance issues, like dominant females evicting subordinates.
- Not evolutionarily stable (ESS): Mutations enabling selfish behaviors can invade and outcompete group-oriented strategies.

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29
Q

What is an Evolutionarily Stable Strategy (ESS)?

A

A strategy that, once adopted by all members of a population, cannot be invaded or replaced by any alternative strategy.

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30
Q

What is kin selection, and how is it explained?

A

Cooperation or altruism directed toward relatives, enhancing inclusive fitness.
Relies on Wright’s coefficient of relatedness (r):
The probability that an allele in an individual is also present in its relatives by common descent.
Higher r indicates closer relationships, increasing the likelihood of altruistic acts.

31
Q

What is inclusive fitness?

A

An individual’s genetic success, including direct reproduction and the impact on the reproductive success of genetically related individuals.

31
Q

What is the Hamilton’s rule?

A

altruism will evolve if: relatedness x benefit to repcipient > cost to donor

32
Q

Inclusive fitness equation:
wi = ai - ci + Erijbij

A

wi = inclusive fitness of donor
ai = direct fitness of donor
ci = effect of altruistic act on donor’s own direct fitness
rij = coefficient of relatedness
bij = increase in fitness of recipient due to action of labour

33
Q

What is life history theory?

A

Framework that examines the distribution of major events over the lifetime of an individual

34
Q

When to start reproducing? What is theoretically the best timing but what actually is the timeline?

A
  • idea strategy is to start reproducing as soon as you are conceived
  • but it isnt seen = most have long developmental stages before they can reproduce
35
Q

What is the diff between semelparous and iteroparous

A
  • semelparous = produce young only once and die
  • iteroparous = produce young multiple times (can be seasonal/cyclical or random)
  • semelparous species invest heavily in their one breeding event
  • iteroparous species spread investment across breeding events
36
Q

What is the pros and cons of early maturation

A

benefits:

  • shorter generation time - offspring will reproduce earlier too = more generations within short period of time
  • high probability of surviving to maturity

costs:

  • shorter time to be able to invest in growth = smaller size
  • lower fecundity - lower number of offspring produced in a single event
  • associated with a shorter lifespan ( fewer breeding attempts)
37
Q

What is the pros and cons of late maturation

A
  • larger size
  • higher initial fecundity
  • associated with longer lifespan (more time to engage with reproductive events)
  • not always iteroparous
38
Q

What is senescence?

A

Senescence is the persistent decline in age-specific fitness components (e.g., survival and reproduction) due to internal physiological deterioration over time.

39
Q

Why do organisms die? Intrinsic vs extrinsic

A
  • intrinsic mortality - mortality due to neglect of maintenance
  • extrinsic mortality - due to stochastic or environmental factors
40
Q

what is the mutation accumulation theory

A

because selection weakens later in life, deleterious mutations that affect older individuals accumulate in populations

41
Q

What is antagonistic pleiotropy?

A

A theory where a gene has multiple effects (pleiotropy), with some beneficial in early life and some detrimental in later life.

41
Q

How does antagonistic pleiotropy relate to aging?

A

It provides a trade-off between early-life benefits (e.g., reproduction) and late-life costs (e.g., senescence).
Genes that are beneficial early on may have negative effects as the organism ages, contributing to age-related decline.

42
Q

How does fecundity (reproductive success) change between early and late reproduction in the context of antagonistic pleiotropy?

A

Early reproduction: High fecundity and fitness benefits.
Late reproduction: Lower fecundity and reproductive success, as investment shifts away from reproduction to survival.

43
Q

What is a sub-case of antagonistic pleiotropy involving somatic repair vs. germline reproduction?

A

When an organism faces a high extrinsic mortality risk, it prioritizes reproduction over somatic repair (body repair) as investing in reproduction maximizes genetic legacy.
As the risk of death increases, somatic maintenance becomes less beneficial, and resources are better spent on germline (reproductive) investment.

44
Q

What causes senescence according to these theories?

A

trade-off between allocating resources to reproduction (which benefits early life) and maintaining the soma (body), which supports long-term survival but takes resources away from reproduction.

45
Q

What is the central tenet of life history theory?

A

tradeoff

46
Q

What are the trade-offs in determining whether an organism is semelparous or iteroparous?

A

Juvenile vs adult survival:
If juvenile survival is low, an organism may benefit from semelparity (reproducing once) to maximize reproductive output early.
If adult survival is more important, iteroparity (reproducing multiple times) may be favored to maximize fitness over time.

47
Q

How does consistency versus instability of the juvenile habitat influence semelparity vs iteroparity?

A

In a consistent habitat, it’s better to have more offspring (iteroparity) because resources are stable for offspring survival.

In an inconsistent habitat, semelparity may be favored as offspring may not survive, and investing all resources in a single reproductive event is more efficient.

48
Q

High initial upfront costs lead to ….

A

semelparity

49
Q

What is the trade-off between semelparity and iteroparity in the context of the American shad migration?

A

Semelparity: In the south (warmer, more predictable environment), the American shad invests in a single reproductive event, using all energy in one breeding season.
Iteroparity: In the north (colder, less predictable environment), the shad breeds multiple times across different seasons, conserving energy and having more reproductive opportunities

50
Q

What is the role of migration costs in shaping reproductive strategies in American shad?

A

In the north (Connecticut River), energy is spent on upstream and return migration, leaving some energy available for reproduction (iteroparity).
In the south (St. Johns River), the warmer temperatures increase metabolic rates and migration costs, making it harder to conserve energy for multiple reproductive events, favoring semelparity.

51
Q

What is environmental plasticity, and how does it relate to the reproductive strategies of American shad?

A

Environmental plasticity refers to the ability of an organism to adjust its reproductive strategy based on its environment.
For the American shad, this means switching between semelparity and iteroparity depending on the environmental conditions (e.g., temperature, migration costs, and predictability of the habitat).

52
Q

What reproductive strategy would you expect in guppies from areas with predators that consume juveniles (e.g., Rivulus)?

A

Guppies would likely produce larger offspring and mature later, investing more in fewer, more viable offspring.

53
Q

What reproductive changes would you expect in guppies moved into locations with Rivulus (predators that eat adults)?

A

Guppies would produce smaller offspring that mature earlier and invest in higher reproductive efforts.

54
Q

What can we conclude about the relationship between predator type and reproductive strategy in guppies?

A

Predation pressure influences reproductive strategies.

54
Q

What are the 2 hypothesis for aging and death?

A
  • rate of living hypothesis
  • fresh blood hypothesis
55
Q

What is the rate of living hypothesis?

A

organisms have fixed budget - by irreparable damage from living. life span negatively correlated with metabolic rate

56
Q

what is the fresh blood hypothesis

A
  • old individuals removed to make room for young
  • damage to DNA occurs
  • not a convincing hypothesis
57
Q

What is interspecific vs infraspecific interactions

A

interspecific = biotic environment
infraspecific = interaction between individuals of the same species

58
Q

What is mutualism?

A

relationship in which organisms of different species interact with mutual benefits; often through the exchange of goods or services

59
Q

What is coevolution

A

change in the genetic composition of one species in response to a genetic change in another.

60
Q

When does coevolution occur?

A
  • Tight ecological relationship (specificity)
  • Reciprocal natural selection
61
Q

What are the 4 important ecological relationships that may coevolve?

A
  • predator/prey
  • parasite/host
  • mutualists
  • competitors
62
Q

Is parallel evolution coevolution?

A

no

63
Q

What are the 2 types of co-evolution?

A

Mutualistic: adaptation in each species increases the fitness of the other species

Antagonistic: adaptation in each species reduces the fitness of the other species

64
Q

Examples of mutualistic relationships

A

Plants and soil fungi for nitrogen extraction.
Flowering plants and insect pollinators.
Corals and unicellular algae for carbon.
Animals and microorganisms in their guts for digestion.

64
Q

How do specialized pollinators and fig trees illustrate mutualistic coevolution?

A

Each pollinator species is specialized to pollinate one type of ficus (fig tree).
The fig tree depends on the pollinator for reproduction, and the pollinator relies on the fig for food resources, forming a mutualistic relationship.

65
Q

which of the following are mutualistic vs antagonistic coevolution methods?
- predator/prey
- parasite/host
- pollination
- seed dispersal

A

mutualistic = pollination, seed dispersal
antagonistic = predation, parasitism

66
Q

What can antagonistic coevolution lead to?

A

cycles, arm race

67
Q

who will win an arms race?

A

life/dinner principle = stronger selection on the species whos individuals are killed by the interaction than on the species where individual just loses their dinner (is selection symetric)

68
Q

match the species with the type of interspecific interaction
- cheetahs/gazelles
- humans/gut bacteria
- flowers/bees
- ground squirrels/chipmunks
- humans/influenza

A
  • cheetahs/gazelles → Predator/prey
  • humans/gut bacteria → mutualists
  • flowers/bees → mutualists
  • ground squirrels/chipmunks → competitors
  • humans/influenza → parasite/host
69
Q

scenario: eat all your stuff bug evolved against pesticide. What type of organism would be best at winning the coevolutionary arms race against it?

A

Specialist predators or parasites would have strong evolutionary advantages in reducing beetle populations.

69
Q

What are the evidence for a mutualistic relationship between ants and fungi?

A
  • direct exchange of goods
  • fitness benefits (greater survival)
  • cospeciation

2B - Genetics & Evolution (9 decks)

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