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47 Cards in this Set
- Front
- Back
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What does cyclical asexuality suggest?
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Cyclic asexuality suggests that asexuality can be advantageous during different periods
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What are believed to be 40 million year old ancient asexuals with only females?
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Bdelloid rotifers
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Asexual lineages have a _______ ______ distribution
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sporadic taxonomic
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In recombination there is crossing over between homo chromosome and independent assortment of chromosomes during meiosis. This leads to what?
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Increased genetic variation between gametes and offspring
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What does gene exchange and recombination do during zygote formation?
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This increases the genetic variation in gametes and offspring.
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What is essentially sex?
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The exchange of genetic material and recombination
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What are the disadvantages of sex?
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Cost of meiosis
Need to find sexual partner STD For females-mixing own genes with mutated male genes Breaks up co-adapted gene-complexes |
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What are the advantages of sex?
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Faster elimination of deleterious mutations
Faster evolution (bringing beneficial mutations together) |
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Explain the cost of males
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In sexual reproduction, in a carrying capacity, on average, the female will produce one male and one female offspring, assuming a 1:1 sex ratio..
But in asexual she will reproduce clonally and only produce daughters: two daughters on average. Assuming that there is no investment by males in the production of progeny, these two daughters will also produce two daughters. Hence, after only two generations, the clone has produced four times as many daughters as the average sexual female. This advantage in daughter production by clones comes as a direct result of the fact that sexual females produce males, which don't make any progeny on their own. Hence, there is a cost of males. It simply means that there is a cost to the sexual population for having 50% on their members not bear their own offspring. |
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What is the cost of meiosis?
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There is 50%elimination of any gene coding for sexuality.
the sexually reproducing female contributes only 50% of her genes to the egg, and this contribution is "diluted" in its influence by the male contribution to the offspring. sexual females are only half as related to their offspring as are asexual females. |
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What is the cost of sexual reproduction for females?
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Females have chance of mixing unmutated genes with mutated male genes
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Describe what Muller was describing in the Ratchet theory?
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This is showing the advantage of having sexual reproduction.
If we were to have asexual reproduction there will be a continual increase in populations that are fit with 0 mutations, then 1, then 2 and so on. While with sexual reproduction, recombination can reconstitute the least-mutated genotype. An asexual population has no way to re-generate the 0-mutation class, while a sexual population can regenerate this class through meiosis, recombination, and syngamy (fertilization). |
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Explain what sex facilitates faster evolution?
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Lets say, there is a mutation that is beneficial to two different families in a population.
Then in sexual, the two different mutations can end up in the same organism through meiosis and syngamy. And of course there is faster evolution in larger populations. In an asexual population, the only way the mutations can end up in the same organism is if the same lineage experiences both mutations. |
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What set up the stage for sexual selection?
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Gene exchange through zygote formation
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What is anisogamy?
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Production of small and large gametes
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In the two gametic system, anisogamy has a tradeoff, explain
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Females-High reproductive effort
-High zygote survival -High parental investment Males-High matting effort -High mobility -High rate of locating over games -Low parental investment |
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What are the limits for fitness in females?
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Females are limited because they put more resources for offspring
Males are limited because they have to have find mate |
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What is the result of the fact males are limited by access to mates? And females having to put more resources into offspring?
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Males will undergo intra sexual selection (male-male competition)
Females will be more choosy with mate selection |
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What is size dimorphism?
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Males and females morphologically, physiologically and behaviorally different
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In great majority of these species, the males are the more "elaborate sex" and this does what to their survival?
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Reduces
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Fill in:
Elaborate traits are _______ to one sex Traits are often ___ expressed until sexual maturity Traits are usually used ____ during breeding season Some traits are ____ only during the breeding season |
limited
not only expressed |
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What is sexual selection?
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Differential reproduction due to variation in the ability to obtain mates
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What is natural selection?
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Differential survival/reproduction due to variation in heritable trait
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Describe the various components of fitness?
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Gametes that are compatible will form zygotes.
The zygotes that are viable will then form adults. The adults will then undergo sexual selection and become parents. |
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What is intra-sexual selection?
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Male-Male competition
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What is inter-sexual selection?
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Female Choice
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Give some of the examples of Male-Male competition (Intra-sexual selection)
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Direct Combat
-Red deer Sperm competition -Damselflies (more sperm, different types of sperm all to produce offspring) This is like a lottery, more tickets (sperm) more change for win (offspring) Infanticide -Lions will go and kill male cubs and make sure that there genes are the only ones in the pride |
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Describe both direct/indirect selection for female preference?
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Direct
Female preference affects female survival or fecundity Indirect female preference doesn't affect female survival/fecundity but preference is genetically correlated with the male trait under sexual selection -Think about this as peacock |
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What is fecundity?
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Parental ability to produce offspring
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Under indirect selection for female preference, the population will be?
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Unstable
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Under direct selection for female preference, the population will be?
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Stable
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Describe the Fisherian runaway process?
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Fisher's explanation is that selection of such traits is a result of sexual preference; that members of the opposite sex find a trait desirable. This preference makes the trait advantageous, which in a circular fashion makes having a preference for the trait advantageous.
The process is termed "runaway" because over time, it would facilitate the development of greater preference and more pronounced traits, until the costs of producing the trait balance the reproductive benefit of possessing it.---Until natural selection on male trait stops this process |
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Describe the genetic correlation between a male trait and a female preference.
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Example:
Long is selected for and short is selected against Long becomes genetically associated with p -Because p and long co-occur together -Because p and short don't co-occur together P increases in frequency -because it is associated with long (long will drag P along to fixation even though there is no direct selection for P) |
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What are the hypotheses for the good gene model?
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Bright Coloration
-indicator of parasite/disease resistance Bilateral symmetry -indicator of developmental genes that generate perfect symmetry Handicap -Straightforward Genetic Complementarity -Male genes that match best the genes of the female expressing the preference |
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What hypotheses of Good Genes are individualistic female choice and which predict female choice is unanimous across entire population?
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Genetic Complementarity-Indivdualistic
Handicap, Bright Coloration, Bilateral Symmetry-all say female choice is unanimous across entire population |
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What is the definition for adaptation?
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Adaptation is meant that a feature/trait that has become prevalent because of a selective advantage due to an improvement of some function.
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Having good fit also is the state of ____ _________
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State of being adaptated
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Selective reason for the ________ of a trait can be different from the selective reason at the ______ of the trait
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maintenance
origin |
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To analyze adaptation you need to what:
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Understand single vs. multiple functions of a trait
Distinguish between original vs. current functions -Origin of a trait - Original Function -Maintenance of a trait -current function Distinguish adaptations from byproducts |
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What is always assumed when going over adaptation?
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Prequisites of Natural selection apply
-Heredity -Variation in heritable traits -Variation in fitness Natural Selection operated in past or is currently operating And to get evidence for natural selection we can do -Engineering functional analysis and optimality analysis |
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What does the leg angle suggest in skeletons?
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That the animal was bipedal
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What is unique about carnivore teeth?
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Anterior teeth are for holding and tearing prey
Molars are for shearing |
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What is unique about herbivore teeth?
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Molars are for grinding
Incisors are for cropping |
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What can functional/engineering analyses and optimality analyses be used for?
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Show details for adaptation
Distinguish adaptation from byproducts |
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What is the definition for Darwinian Fitness?
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The most fit types survive/reproduce best because of recognizable inherent properties
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Fitness is measured a priori not post hoc
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Meaning that fitness is determined before
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What are some of the limitations of adaptions?
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Phenotypes are compromises
-Giraffe neck reaching high or low Constraints cannot be modified/eliminated -The loop in a the recurrent laryngeal nerve Evolutionary time lags prevent adaptation -The thing that made the adaptation has now changed |
