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58 Cards in this Set
- Front
- Back
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Define: Natural Selection |
The average difference between survival or fecundity of individuals with certain phenotypes, compared to individuals with other phenotypes. |
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T/F: Gender can be a component of the phenotype |
True |
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Define: Sexual Selection |
Difference, among members of the same sex, between the average mating success of individuals with a particular phenotype versus individuals with other phenotypes |
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Can sexual selection occur across phenotypes? |
Yes |
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What are the two meanings of sexual slection? |
1. Intrasexual selection: Variance in mating due to traits that affect contests between males for access to females (within a sex) 2. Intersexual selection: Variance in mating due to female choice or "preference" (=mate choice) for some male phenotype (across sex) |
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Define sexual dimorphism |
When phenotypic traits differ between the sexes of a species |
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T/F: All sexual dimorphisms can be explained by natural selection |
False. Some sexual dimorphisms are difficult to explain by natural selection |
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When a trait can't be explained by natural selection, what other form of selection is usually used to explain this trait? |
Sexual selection |
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Define: Anisogamy |
The fusion of two dissimilar gametes from two sexes of the same species. (i.e. when the human female egg fuses with a human male sperm) |
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Define: Isogamy |
The fusion of two gametes with similar shape and size. |
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T/F: Human reproduction is the result of isogamy |
False. Isogamy is defined as the fusion of two gametes with similar shape and size. Human reproduction is the result of Anisogamy, the fusion of two dissimilar gametes. The human male sperm is several times smaller than the human female egg. |
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T/F: Most females spend as much as 3x their basal metabolic rate in producing eggs |
True |
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What is the amount of energy spent by males in producing sperm? |
10^-3 BMR |
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What is the amount of energy spent by females in producing eggs? |
3x BMR |
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T/F: Females always make a larger parental investment than males |
False. While females typically make larger parental investments than males they do not ALWAYS. There are many species in which the males make larger parental investments than the females. |
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Which of the following is incorrect A. Typically, female's reproductive success is relatively small and is likely to be limited by the number of eggs that she can carry B. Typically, males reproductive success is very high. C. Sexual reproduction inevitably leads to different variance in reproduction and therefore sexual selection. D. Females always practice sexual selection against males as females have a small reproductive success. |
D.Females always practice sexual selection against males as females have a small reproductive success. |
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Female reproduction is limited by ________________ while male reproduction is limited by _________________ |
The number of eggs possible ; the number of mates possible. |
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T/F: In hermaphroditic species such as Bladder snails, sexual reproduction is favored over selfing |
True |
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Describe the experiment |
200 snails approximately 100 had greater than or equal to one offspring as either male or female. 2/3 alternated in male or female roles and most individuals are biologically equivalent, independent of reproduction. Compulatory success (# of matings) were not equal to the mating success. Mating success as males did not correlated with success as females therefroe as indiivduals, making eggs didn't diminish capacity to make sperm and vise versa. The point of the experiment was to determin if male mating success correlated with male reproductive success and if female mating success correlated with female mating success. |
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Describe the results shown |
Males have a linear relationship so it seems that the number of times mated is strong and correlates with the males reproductive success. Females however do not correlate. This supports the hypothesis that males' reproductive success will correlate with their mating success because they're energy is more invested in finding mates while female's reproductive success will not correlate to mating success as they're energies are primarily invested in the offspring and not in finding a mate. |
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Describe the results |
These reflect the offsprings resulting from different numbered matings between male and female rough-skinned newts. The males who have mated with greater numbers of offspring have shown to have a steep linear relationship to an increased number of offspring. Females however does not show such a steep curve. Females who mated with multiple mates only show a slight increase. This is due to the limitation in gametes that females have. With a limited number of eggs produced there leaves a limited number of offspring born to females. Those who mate with multiple mates only have a slight increase as they are likely not to have a gap between pregnancies.
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Describe Bateman's Principle |
Greater variance in reproductive success among males than females. |
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Explain Bateman's Principle |
Bateman's Principle states "Greater variance in reproductive success among males than females" This is because male gametes are not as limiting and a male's reproductive success increases linearly with increasing number of mates. As a result, sexul selection is higher on males. |
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Describe a scenario in which sexual selection is stronger for males. |
This would happen if the females have high quality eggs, provisions, pregnancy. This results in choosy females. Males will compete with one another in order to gain the attention of the female. |
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In situations where females are choosy and males are not, females will exhibit _______________ while males exhibit ________________. A. Inter-sexual selection; Intra-sexual selection B. Inter-sexual selection; Inter-sexual selection C. Intra-sexual selection; Inter-sexual selection D. Intra-sexual selection; Intra-sexual selection |
A. Inter-sexual selection; Intra-sexual selection |
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What are the three methods in which males compete with other males? |
1. Combat (contest) 2. Sperm competition 3. Infanticide |
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Combat was a method of intra-sexual selection between males. What specific combat methods are there |
1. Actual combat 2. Visual signals (Color, displays) 3. Vocal signals (songs) |
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T/F: Sexual selection can be very strong and often opposes natural selection |
True |
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T/F: Sexual selection can lead to exaggerated and sometimes maladaptive developments of males |
True |
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How do male Galapagos marine iguanas compete and how can that be seen as maladaptive |
Larger iguanas are able to compete for better rocks to warm body temperatures. These rocks help to attract females which leads to breeding. The size of the males however become difficult to maintain. The larger the iguana's size, the greater algae they must consume. This causes them to have to go into the cold ocean more frequently. |
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In what ways can males exhibit sperm competition? |
1. Large ejaculates 2. Mate guarding 3. Prolonged copulation 4. Copulatory plugs 5. Sperm "scoops" 6 Post copulation pheromone changes |
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The male dragon fly exhibits which type of sperm competition? A. Large ejaculations B. Prolonged copulation C. Sperm "Scoops" D. Mate guarding |
C. Sperm "Scoops" |
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Explain why male lions practice infanticide |
When offspring are present, females are not likely to be willing to reproduce. When an incoming male lion kills the leader of the pride, they also kill the offspring causing the females to be open to reproduction. |
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Explain how female red-collared widowbirds practice female choice through intersexual selection on males. Explain why this is costly for the males |
Male red-collared widowbirds have long tails. Females choose potential mates based on the length of their tails. Although the longer tails provide a reproductive advantage to males, it is extremely energetically costly. The energetic costs are compensated for by higher nesting activity and higher reproductive rates. |
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Explain how female frogs practice female choice through intersexual selection on males |
Females prefer males with longer croak calls. |
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Why do some females practice intersexual selection? |
1. Better genes for their offspring 2. Direct benefit through acquisition of resources 3. Preexisting sensory biases |
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T/F: Assortive mating within a population between males with the most exaggerated trait and females with the strongest preference can lead toa genetic correlation between trait genes and preference genes. |
True |
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Explain how male display and female preference can lead o genetic correlation. |
Increased reproductive success of males with preferred display will increase the frequency of that display and preference genes exhibited by females. This reinforces assortative mating since offspring carry genes for both exaggerated tail length (male) and strong preference (female). This causes the male and female traits to be self-reinforcing and causes the trait to evolve way beyond the point where it indicates overall genetic quality. Runaway of the male trait can proceed to a point of exaggeration where it actually decreases male fitness. This creates a situation where the only benefit to female choice is that her sons inherit the most attractive state of the trait. This is in direct contrast to the "Good Genes" hypothesis and has been referred to as the "sexy son" hypothesis |
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Explain how genetic correlation between male display and female preference can lead to runaway |
If males exhibit a trait that is preferred by females, they are likely to reproduce at a higher rate. This causes the male and female traits frequency to increase. Eventually the male trait will evolve beyond the point where it indicates overall genetic quality at which point the male trait runs away and actually decrease male fitness |
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Describe how Stalk-eyed flies exhibit preference due to genetic correlation between male display and female preferene |
Stalk-eyed flies have heritable variations for the distance between eyes in males and for female preference for stalk length. Courtship in stalk-eyed flies involves displays by males in a lek. Females tend to choose males with the largest stalks and leks tend to form on the root hairs of plants. It was seen that female preferences correlate with male display. Females of short eye stalk preferred males with short eye stalks while females with long eyestalks preferred males with long eye stalks. |
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Describe the "Good genes hypothesis" |
Females risk substantial loss of fitness following an unsuitable mating. Therefore, females should evolve to choose males with high genetic quality, causig their offspring to inherit "good genes". Thus any male trait that is correlated with genetic quality (good genes) could be used by females as a cue indicating beneficial matin partners. |
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What is a "condition indicator" model and how does it fit into the good genes hypothesis |
The good genes hypothesis states that females will choose males with high genetic quality to ensure that their offspring inherit "good genes". In order for females to recognize males with good genes there must then be some kind of physical indication of quality genetic material. The "condition indicator" model is a way that females can determine which males have quality genes and which males do not. For example, males with allele T can develop the indicator trait (i.e. long tail feathers) only if they are in good physiological condition owing to also carrying allele B (beneficial) at another locus. Basically, its a way that females can tell if males have quality genes and those genes must be beneficial enough in order to persist in the male population. |
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Scientists observed a collection of frogs during mating season. He found that different males exhibited different calls at different lengths in order to attract females. If call length is a sign of good genes, what can you determine will happen in second generation of offspring during mating season based on the good gene hypothesis? A. Female frogs will likely choose males who exhibit short mating calls B. Female frogs will likely choose males who exhibit long mating calls C. There will be an equal distribution of females who prefer to mate with males who exhibit short mating calls and males who exhibit long mating calls. D. Females choose mates arbitrarily and randomly |
B. Female frogs will likely choose males who exhibit long mating calls. |
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Explain how hanger flies obtain direct benefits through acquisition of resources during reproduction |
When males approach females, they present the females with insect food items in order to mate. While the female feeds, the male can fertilize. |
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Which of the following animals have females which benefit directly througho acquisition of resources? A. Frogs B. Stalk-eyed flies C. Red-collared widow birds D. Hanging flies |
D. Hanging flies |
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The graph depicts hangingflies and the size of the gift in relation to the duration of copulation. Which of the following can be true based on the data? A. The size of the gift correlates with the duration of copulation. B. Larger gifts allow a longer fertilization time and thus more sperm transferred. C. Larger gifts are directly beneficial to the female by providing more nutrients to produce more eggs. D. All of the above |
D. All of the above |
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Which of the following can be true based on the graph regarding stalk-eyed flies? A. Longer stalk-eyed flies are preferred over all other stalk-eyed lengths B. Short stalk-eyed flies are preferred over all other stalk-eyed lengths C. Runaway selection will result as a result of assortative mating D. All of the above |
C. Runaway selection will result as a result of arbitrary selection. *Remember that in this experiment we found that small stalk-eyed females preferred small stalk-eyed males while long stalk-eyed females preferred long stalk-eyed males. |
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A group of scientists observed frogs mating and saw that females preferred males who exhibited longer calls. The scientists believed that this may be a way that frogs can exhibit superior genetic quality. In order to test their hypothesis they separated the tadpoles into 4 groups: long call + high food diet, Long call + low food diet, Short call + high food diet, short call + low food diet. Which of the following best describes their results? A. The tadpoles who were put on a high food diet had a greater chance of survival. B. The addition of the high food diet provided tadpoles with shorter calls to survive better than those with low food diets C. Despite the high food diet, all of the long called tadpoles survived better than the short called tadpoles. D. None of the above |
C. Despite the high food diet, all of the long called tadpoles survived better than the short called tadpoles. |
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How do female house finches choose a mate? |
Females choose a mate through the use of a direct indicator model. By selecting males who are bright red they associate these males as being able to bring food to nestlings at a higher rate. |
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Which of the following animals exhibit female who select mates through a preexisting sensory bias? A. House Finch B. Water Mites C. Hanging flies D. Frogs |
B. Water mites |
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Explain the courtship ritual of the watermite |
The courtship behaviors of the water mite is believed to have evolved to exploit the predatory behavior (net stance) of females. Female preferences for male traits may evolve before the male traits. |
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T/F: The courtship behavior of the watermite evolved to exploit the predatory behavior of females |
True |
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T/F: All sexual selection are those in which females select on males |
False. There are instances in which males select on females |
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In what instance would males sexual selection on females occur? |
When there is bigger offspring investment by males |
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Explain why prairie dogs have males who infer sexual selection on females?
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Female prairie dogs are only fertile once a year. When this time comes males select which females to mate. As a result, the females who can mate with the most males will have the largest number of offspring. |
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Explain why broad-nosed pipefish have males who infer sexual selection on females |
Males provide parental care, brood, and versatile eggs/embryos and nutrients. The males have equal to or greater than investment than females. Also, the females spend less time producing the eggs than do the males who raise them. |
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Determine if the graph represents males choosing females or females choosing males. Support your answer
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The graph shows males choosing females because based on the last graphs there is a steeper correlation regarding the number of mates for females and the number of offspring. Also based on the first graph you can see that a large number of females do not mate indicating that males are the choosing sex in this case. |
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These graph likely represents a species in which
A. males take care of babies B. There is a sexual selection on females C. Most males get to mate D. Females are the choosy sex E. There is no intersexual selection |
D. Females are the choosy sex. |
