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What is sexual dimorphism?
A difference in males and females in a species
What is natural selection?
Differential reproduction due to variation among individuals in survival and fecundity
Sexual selection is what?
- Differential reproductive success due to variation among individuals in success at getting mates
- if variation is heritable, then variants that increase reproductive success will become more common
Why does sexual selection lead to dimorphism?
- Differences in the energy and time expended to care for young (at expense of parents future reproductive success)
- Access to mates limit reproductive success in males
- Variance in reproductive success can be great, typically for males
What is intrasexual selection?
- members of the sex subject to strong sexual selection will be competitive
- male male combat
- sperm competition
How do smaller males successfully mate?
- try and try again
- ejaculate ahead of time
- be a sneaky male
What male traits are under sexual selection?
- ejaculate size
- prolonged copulation
- copulatory plugs
- pheromones to reduce females attractiveness
- removal of prior males' sperm
What is intersexual selection?
Members of the same sex are subject to weak selection will be choosy
What is the early treatment of female choice?
- Species recognition
- Overcoming female reluctance to male
What is the null model of female choice?
- Females preferences are arbitrary
- both display and preference are neutral and heritable
What is assortive mating?
Genetic correlation between trait and preference for the trait
What is runaway sexual selection?
When the correlation does not cross with the equilibrium line
Explain the theory that females have pre-existing sensory biases.
Preferences may be shaped by natural selection in non-reproductive contexts
Explain the theory that females receive benefits from being choosy.
Females will receive shelter or nutrients for better survival
Explain the theory that choosy females bet better genes for their offspring.
Females select for the dominant genes in males so their offspring could have them
What is Pre-copulatory sexual selection?
process to gaining mating opportunities
What is post copulatory sexual selection?
- Copulatory courtship
- Sperm competition
- Cryptic female choice
When do males become a limiting resource for females?
When males invest more parental care per offspring
What is the prediction of sexual selection on male flowers?
Access to pollinators limit reproductive success of pollen donor and leads to evolution of showy flowers driven by effect on male RS
What were the results of the wild radish experiment?
One can conclude that reproductive success by male function is limited by pollinator visits (both white and yellow flowers tend to produce the same amount of fruit)
What is mutual benefit?
both actor and recipient benefit
What is selfishness?
Actor benefits and recipient does not
What is altruism?
Actor does not benefit, but recipient does
What is spite?
Act that harms both the actor and the recipient
What is Hamilton's rule?
Altruism will increase in frequency if benefit of recipient by the relatedness between actor and recipient outweighs the cost of to the actor is greater than 0
What is inclusive fitness?
- direct fitness(reproduction by the individual on its own) + indirect fitness(additional reproduction by relatives made possible by the individual’s action)
- Natural selection favoring alleles that increase indirect fitness = kin selection
What is cooperative breeding?
Non-breeding helpers assist parents in nest-building, nest defense, and/or food delivery
What is geometric relatedness?
- Genetic similarity of two individuals in the context of the population to which they belong
- Distance between individual allele frequency and population allele frequency
- Related ness between actor and Recipient one and the relatedness between the actor and recipient two
What is brood parasitism?
- Cuckoos and cowbirds: Cuckoos lay eggs in cowbirds nests and depress the success of cowbirds
- Carrion crow and cuckoos
- A mutually beneficial relationship
- A cuckoo chick in a crow’s nest helped the crows survive better because predation rates are lower. We found that the cuckoo babies make a really nasty secretion when disturbed
What is parent offspring conflict?
Comparing the beneficial status of the chicks compared to how much of a cost it is to take care of them.
What is reciprocity?
Exchange of fitness benefits over time (reciprocal altruism)
What are eusocial animals
- Overlapping generations
- Non-reproductive individuals care for young
What are the three hypotheses of eusocial animals?
- The haplodiploidy hypothesis
- The monogamy hypothesis
- The ecology and life history hypothesis
What is the haplodiploidy hypothesis?
- Males develop from unfertilized eggs (males are haploid)
- Relatedness of sisters go up
- But, several eusocial species are not haplodiploid
What is the monogamy hypothesis?
If an individual’s parents are monogoamous then future sibling will be full-sibs leads to inclusive fitness for raising full sibs = inclusive fitness for raising own offspring
What is the ecology and life-history hypothesis?
- A combination of factors favors eusociality
- Construction of complex nests
- Extended care of larvae
- Impossible for female to breed on her own
What is an individual organism's life history?
An individual’s pattern of allocation, throughout life, of time and energy to different activates (e.g., growth, repair reproduction)
What is senescence?
Age-related decline in fertility and survival probability
What 2 theories explain why senescence persist?
- The rate of living theory
- The evolutionary theory
What is the rate of living theory?
- Aging is caused by accumulation of irreparable damage to cells and tissues
- Errors in DNA replication, translation, transcription
- Accumulation of toxic metabolic by-products
What are some predictions of the rate of living theory?
- Aging rate is correlated with metabolic rate, if it is, then energy expenditure per gram should be about equal across species, but it is not.
- Species cannot evolve longer life spans, but there is room to increase lifespan
- There is a positive correlation between telomere length deterioration and longevity
What is the evolutionary theory?
Aging is caused by failure to repair cell and tissue damage
What is the mutation accumulation hypothesis?
Selection is weak against deleterious mutations with effects late in life
What is the antagonistic pleiotropy hypothesis?
- On balance, mutations that increase fitness in early life (but costs later in life) will be advantageous when a single gene affects more than one trait
- ecological mortality
What is the prediction of the antagonistic pleiotropy hypothesis?
lower ecological mortality rate leads to delayed senescence
According to all of the senescence hypotheses why would you expect selection for delayed senescence if the ecological mortality rate is lower?
- More individuals getting older, so mutations are showing up
- Late acting problems dont show up until the organism gets older
What is reproductive senescence?
Reproductive capacity declines early but other physiological capacity doesn’
What is the grandmother hypothesis of reproductive senescence?
- Women provision older (still dependent) children it limits ability to have more kids
- As a woman gets older
- Not likely to raise another baby from birth
- Pregnancy and childbirth risks increase
- Her daughters start having children
- Trade off: investment in children vs. grandchildren for older women: greater benefit from investing in grandchildren
What is Lack's Hypothesis?
- Selection will favor the clutch size that produces the most surviving offspring
- Trade off
- Survival down
- As clutch size up
- Occurs because the parent can only feed a certain amount of offspring
What are some crucial assumptions of Lack's hypothesis?
- No trade-off between a parent’s reproductive effort in one year vs. survival/reproductive success in future years
- The only effect of clutch size on offspring is via their survival
What is the germ theory of disease? Who developed it?
Disease is caused by different and particular germs, Louis Pasteur
What is coincidental evolution?
Virulence is an accidental by product of selection on other traits
What is short-sighted evolution?
- Selection for success within the host leads to virulence
- Excessive virulence leads to reduced transmission to new hosts
What is Within-host fitness vs. transmission trade-off?
- A pathogen cannot reproduce in a host w//o causing some harm
- Uses energy and nutrients from hosto Produces metabolic wastes
- And if host mounts an immune response leads to costs
- Trade off
- Higher within host reproduction lead to higher transmission rate lead to …but if pathogen reproduces too quickly lead to host debilitated lead to reduced transmission rate
What are the different types of phage transmission?
- Direct transmission: Direct contact with host
- Transmission by vectors: Contact with a carrier of the pathogen without getting infected
How do death rates differ in direct and vectorborne pathogen transmission?
Death rates of vectorborne diseases have higher death rates than directly transmitted infections
What could be the advantage of having a fever?
Fever increases the temperature in your body so that the micro bacteria are unable to survive
What would you like to do?
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