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Life Sci 2D03 > Chapter 12 > Flashcards

Chapter 12 Flashcards

1
Q

Mate Competition vs Mate Choice

A

Mate Competition (intra-sexual selection): when members of one sex compete with one another for mating opportunities
Mate Choice (inter-sexual selection): when members of one sex exhibit distinct mating preferences

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2
Q

Anisogamy VS Isogamy

A

ANISOGAMY: the existence of differently sized gametes (small and large) in different sexes
ISOGAMY: the production of gametes of the same size by all individuals (algae, fungi)

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3
Q

How did Anisogamy evolve from Isogamy? Explain using the Parker Model

A

3 Assumptions:
a) In the ancestral marine environment, individuals in a population that retain reproductive compatibility produce different sized gametes
b) Each parent has a fixed amount of energy to allocate to gamete production, resulting in a size-number trade-off: as the number of gametes produced increases, their size decreases
c) Zygote viability is related to its size, larger zygotes have higher viability since they contain more resources for survival
Explanation: Parker’s model suggests that producing small gametes is advantageous since many gametes are produced and large gametes are advantageous since they have high survival. However, intermediate-sized gametes have the lowest fitness. meaning the highest fitness individuals are “proto-males” or “proto-females” (two different reproductive strategies)

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4
Q

Bateman’s Hypothesis VS Triver’s Parental Investment Theory

A

Bateman’s Hypothesis: female reproductive success is most strongly limited by the number and success of eggs that a female can produce, whereas male reproductive success is limited by the number of mates a male contains (meaning greater variation in male reproductive success and more intense sexual selection on males)
Triver’s Parental Investment Theory: predicts that the sex that pays the higher cost of parental investment should be choosier when it comes to mates, the other sex will then experience more intense sexual selection

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5
Q

T or F: when one sex has greater parental investment, they are are not as sexually receptive as the other sex since they are caring for current offspring, which results in a difference between sexually receptive females and males (operational sex ratio), a large skew in this ratio leads to greater intensity of sexual selection on the non-caring sex, meaning choosy females and a higher variation in male reproductive success

A

True

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6
Q

Weapons vs Ornaments

A

Weapons: exaggerated morphological traits used in competition with individuals of the same sex
Ornaments: exaggerated morphological traits used to attract mates

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7
Q

Research 12.1: Weapon Size & Mating Success in Dung Beetles

A

a) Male dung beetles fight with each other to defend dung piles, where females dig subterranean tunnels to mate and raise their offspring

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8
Q

DUNG BEETLES & HORN SIZE: Research Question

A

Do large horns provide an advantage in male to male fights?

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9
Q

DUNG BEETLES & HORN SIZE: Methods

A

a) Staged fights between males in artificial nesting arenas (two panes of glass placed 5mm apart and filled with soil and dung)
b) They placed a single female in the arena, which quickly dug a tunnel
c) Two males, closely matched for body size but not horn length were introduced with the females
d) The winner was deemed to be the males that successfully entered and remained in the tunnel after 24 hours; most winners mated with the female

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10
Q

DUNG BEETLES & HORN SIZE: Conclusion

A

a) Males tried to hook their horns under their opponent’s head, also using their horns to push opponents out of the tunnel
b) In contests between small beetles, the larger males or the male with the longer horn won most contests
c) In contests between larger beetles, large horn size along was the most important predictor of success
d) Conclusion: the maintenance of long horns in male dung beetles can be explained by sexual selection driven by male-male competition

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11
Q

Research 12.1: Ornaments & Mate Choice in Peafowl

A

a) Male peacocks possess extremely large tails whose feathers contain brightly coloured ocelli (eyespots)
b) Since males fan out their tail when displaying to females, it seemed likely that female mate choice involves tail morphology
c) Early work showed the females prefer to mate with males that have the most ocelli, males with the most ornamented tails
d) Before peahens select a peacock mate, males must compete to establish and defend a display site, a LEK
e) Many males aggregate on a lek, a location that LACKS resources where they display to females using behaviours like vocalizations and fanning of the tail

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12
Q

PEACOCKS & ORNAMENTS: Methods

A

a) Captured and colour-banded males and females in early spring
b) They measured each male’s tail length and body size, and counted number of ocelli
c) Recorded male-male interactions during the breeding season, along with number and duration of male tail displays to females (number of vocalizations, copulations)

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13
Q

PEACOCKS & ORNAMENTS: Results

A

a) They found intense competition for display sites, as only 45 of 61 males successfully defended a site, meaning 25% had little chance to reproduce
b) Found significant positive correlations between the likelihood of defending a display site and both body size and tail length
c) Only 12 males obtained copulations, and over one third of all copulations were obtained by a single male
d) In general, males that had high display rates and the most ocelli obtained the most copulations, although not the largest males

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14
Q

PEACOCKS & ORNAMENTS: Conclusion

A

a) Both mate competition and mate choice have played a role in the evolution of the peacock tail
b) First, only a subset of males successfully defended a display site, all of which were large individuals (tarsus) with long tails (train)
c) Second, females strongly preferred males with high display rates and tails with many ocelli
d) Together, male competition and female choice have favoured the evolution of males with long, elaborately ornamented tails and high display rates

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15
Q

Research 12.1: Male Mate Choice in Pipefish

A

a) Males can also be choosy, favouring the evolution of female secondary sexual traits in some species
b) In pipefish, females compete for males that invest heavily in parental care
c) Females transfer their eggs to the males’ egg-brooding structure, the male then fertilizes the eggs and cares for them as they develop, the males become pregnant
d) Males should be the more choosy sex and female-female competition for mates may be intense, also may expect females to display secondary sexual ornaments
e) Female pipefish possess a secondary sexual ornament: a temporary striped pattern on the side of the body that is displayed only during competition between females and when courting males, a courtship dance
f) Normal pipefish body colouration is quite cryptic but the ornament makes the female stand out and so is likely to increase predation risk, making it costly

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16
Q

PIPEFISH & MALE MATE CHOICE: Hypothesis

A

Males use a sexually selected trait in their mate choice

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17
Q

PIPEFISH & MALE MATE CHOICE: Prediction

A

Males should spend more time and mate more often with those females that display their temporary striped pattern (ornament) the most

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18
Q

PIPEFISH & MALE MATE CHOICE: Methods

A

a) Day 1, no interactions were allowed
b) Conducted a simultaneous-choice test with a single male and two enclosed females that were matched for size
c) Recorded the amount of time the male spent in front of each female, how often a female displayed her ornament, and how often the male engaged in a courtship dance with each female
d) Day 2, interactions were allowed
e) Conducted the same experiment but with all dividers removed so that individuals could interact
f) Recorded total time dancing, latency to dance, and copulations with each female
g) Removed and counted all eggs from the male’s brood pouch

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19
Q

PIPEFISH & MALE MATE CHOICE: Results

A

a) Males spent more total time and time dancing, and had a shorter latency to dance with the female that displayed her ornament more
b) The more ornamented female contained more copulations

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20
Q

Research 12.1: The Sensory Bias Hypothesis in Guppies

A

a) How does a male trait become a focus of female mate preference?
b) One explanation is the Sensory Bias Hypothesis: female mating preferences are a byproduct of preexisting biases in a female’s sensory system
c) These biases are presumed to have evolved in a non-mating context, with males evolving traits to match those biases
d) Female guppies prefer to mate with males that display the greatest amount of orange colouration, derived from carotenoids obtained in their diet (which play a key role in immune system function), but colourful guppies are also easier for predator to spot
e) In stream populations where predation risk is high, female preference for orange is reduced, and males display less orange body colour than do males in other populations with low predation risk
f) Guppies in the wild are attracted to and consume orange coloured fruits that fall into the water

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21
Q

GUPPIES & SENSORY BIAS HYPOTHESIS: Hypothesis

A

Guppies have an innate preference for orange food items because they contain carotenoids, and this preexisting bias favours males that display orange colour

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22
Q

GUPPIES & SENSORY BIAS HYPOTHESIS: Prediction

A

Both male and female guppies should be attracted to orange-coloured objects since their colour is associated with the presence of carotenoids

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23
Q

GUPPIES & SENSORY BIAS HYPOTHESIS: Methods

A

a) In one set of studies, they placed small discs on a leaf in the water, discs could be red, orange, green, purple, blue, white, yellow, or black
b) They noted all guppy approaches, pecks at objects, and the sex of the individual
c) They also conducted a similar experiment in the laboratory where discs were placed in an aquarium

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24
Q

GUPPIES & SENSORY BIAS HYPOTHESIS: Results

A

a) Both male and female guppies exhibited a strong attraction to the orange and red discs, and the strength of the preference for orange was correlated with female mating preference for the colour orange
b) In populations with the strongest female preference for orange males, both sexes displayed the strongest attraction to the orange discs

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25
Q

Research 12.6: Mate Copying in Guppies

A

a)

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26
Q

Research 12.2: Female Choice & Nuptial Gift in Butterflies

A

a) Nuptial Gift: a physical resource like a food item that an individual provides to a potential mate to enhance mating success
b) Many arthropods provide nuptial gifts before or during mating
c) In some species, females prefer to mate with larger males since they offer larger nuptial gifts
d) Green-veined white butterflies provide a SPERMATOPHORE: sperm packaged within a protein-rich structure produced by male accessory glands, as a nuptial gift
e) Once inside a female, the spermatophore disintegrates, releasing nutrients, which the female can use to reproduce
f) Since adults feed mainly on nectar, the spermatophore can represent an important source of protein
g) The spermatophore can be directly inserted, placed as a capsule, transferred by a spermatophore structure, or placed within a sperm web or sperm packet

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27
Q

BUTTERFLIES & NUPTIAL GIFTS: Research Question

A

Does female egg production vary positively with the size of the nuptial gift received from a male?

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28
Q

BUTTERFLIES & NUPTIAL GIFTS: Methods

A

a) Quantified how much resource transferred from the male to the female’s egg production by radioactively labelling leaves that they’d feed males with
b) Calculated the rate the spermatophore disintegrated in the female’s abdomen to calculate the amount of spermatophore the female received
c) Allowed a female to mate with a single mate and lay eggs, which were then collected and dried
d) Female’s eggs, abdomen, and thorax were tested for radioactivity to quantify the amount of male nutrients transferred from the male to the female in the spermatophore

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29
Q

BUTTERFLIES & NUPTIAL GIFTS: Conclusion

A

a) Females receiving larger spermatophores produced more eggs, showing a direct benefit of male nuptial gift on female fitness
b) Females can benefit directly by mating with males that offer large nuptial gifts

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30
Q

Research 12.2: Female Choice & Territory Quality in Lizards

A

a) Another direct benefit of mate choice for females is access to high-quality resources defended by a territorial male
b) Males defend territories where they display to females from rock perches, the quality of a territory is based on rockiness, rocks provide perches not only to display to females but also to spot predators
c) Rocks also increase the range of “microclimates” available for thermoregulation, which is important for lizards
d) Previous work demonstrated that offspring growth and survival are greater when females lay eggs within male territories that have many rocks, the highest quality territories

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31
Q

LIZARDS & TERRITORY QUALITY: Research Question

A

How does territory quality affect female choice and fitness?

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32
Q

LIZARDS & TERRITORY QUALITY: Methods

A

a) They manipulated territory quality after males had established territories but before females became receptive and selected males
b) Dominant males settled on territories with the most rocks (highest quality)
c) They moved 10-40 rocks from territories of large, dominant males to the territories of small neighbouring males
d) This separated high-quality males from high-quality territories
e) After breeding season, they measured egg mass of each female

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33
Q

LIZARDS & TERRITORY QUALITY: Conclusion

A

a) Females strongly preferred the improved territories, even though they were occupied by small males
b) Of 51 females in the population, 37 settled on the improved plots
c) Females on improved territories laid eggs sooner and producer larger egg masses, demonstrating a direct fitness benefit for females that select high-quality territories
d) Females appear to select mating partners based on male territory quality

34
Q

Fisher’s Runaway Selection

A

a) Ronald Fisher proposed a genetic explanation for the evolution of exaggerated secondary sexual traits
b) Assumed that females select mates based on a particular trait that varies among males
c) This trait could evolve because of (1) fitness advantage and (2) female preference for it.
d) The trait indicates male quality, if female preference for a trait and the trait itself have a genetic basis, female offspring will prefer the trait and male offspring will express it
e) In sum, the male trait should co-evolve with the female preference and become increasingly exaggerated, RUNWAY PROCESS
f) This would continue until the benefit it provided through sexual selection was outweighed by the disadvantage entailed through natural selection (increased predation risk)
g) Runway selection may help to explain the evolution of a variety of sexual trait and mating preferences in diverse taxa

35
Q

Zahavi’s Handicap Principle

A

a) Zahavi proposed an alternative hypothesis to explain how female choice could affect the evolution of male traits
b) Suggested that exaggerated sexual characteristics allow the choosing sex to assess mate quality
c) The exaggerated trait is a “test imposed on the individual” by natural selection
d) Only high-quality males should thus be able to display the most exaggerated form of the trait, a handicap
e) Handicap Principle Hypothesis: well developed secondary sexual characteristics are costly because they handicap a male’s survival
f) Females should prefer such males since they must have excellent genotypes to overcome the handicap
g) More work demonstrated that exaggerated secondary sexual traits must be costly in order for them to be a reliable indicator of male genetic quality, or good genes
h) Traits being costly are reliable indicators of male genetic quality if only the healthiest and most vigorous males can produce them

36
Q

Research 12.3: Mate Choice for Good Genes in Tree Frogs

A

a) The Good Genes Hypothesis predicts that females should base their mating decisions on costly male traits to obtain indirect genetic benefits
b) Many males call to attract females in a chorus but calling is costly since its energetically expensive and can make an individual more susceptible to predators
c) European Tree Frogs are ideal to examine the genetic benefits of female choice since females initiate all matings and males do not interrupt mating pairs, male-male competition is assumed to be weak

37
Q

TREE FROGS & GOOD GENES: Research Question

A

Do females assess male quality on the basis of their vocalizations?

38
Q

TREE FROGS & GOOD GENES: Methods

A

a) They visited four neighbouring ponds in western Switzerland to determine which males were calling in the chorus
b) A total of 15 calling males were captured and identified from a photographic data bank (individuals’ black lateral line has unique colour patterns) and a buccal sample was taken for genetic analysis
c) To determine male mating success and the fitness of the offspring, the team visited the ponds every four days in daylight to collect egg masses
d) All clutches were reared in the laboratory until hatching, ten offspring from each clutch were reared and each tadpole was weighed twice to record its growth rate
d) Tadpole survival was determined at 28 days and all individuals were then genotyped
e) From this data, researchers could determine attractiveness of each male, defined as the number of females he mated with divide by the number of nights he called during the breeding season

39
Q

TREE FROGS & GOOD GENES: Results

A

a) Only ten of fifteen males sired any clutches, indicating that males varied in their attractiveness to females and that females were selective
b) Offspring growth rate was positively correlated with the father’s attractiveness, meaning males that sired more offspring produced tadpoles with higher growth rates
c) Offspring growth rate is positively related to fitness so they concluded that females do indeed select males for genetic benefits that result in higher fitness for offspring

40
Q

Research 12.3: Good Genes and The Hamilton-Zuk Hypothesis

A

a) William Hamilton and Marlene Zuk proposed that parasites and pathogens play an important role in sexual selection when secondary sexual traits are costly and condition dependent
b) For example, males may vary in their immune response: some males will have alleles that confer greater resistance to pathogens than will others
c) If pathogens reduce male vigour, only males with superior disease resistance will be able to display exaggerated secondary sexual traits, females that mate with such males will benefit by passing these alleles to their offspring
d) Hamilton-Zuk Hypothesis predicts that females should prefer to mate with males that have the greatest expression of secondary sexual traits since such males have the highest levels of immunocompetence, if male immune system function is heritable

41
Q

FIELD CRICKETS & GOOD GENES: Hypothesis

A

The Hamilton-Zuk Hypothesis predicts that females should prefer to mate with males that have the greatest expression of secondary sexual traits since such males have the highest levels of immunocompetence, if male immune system function is heritable

42
Q

FIELD CRICKETS & GOOD GENES: Methods

A

a) Males produce energetically expensive courtship songs that contain high and low frequency ticks and this secondary sexual trait is used by females to select a mate
b) They quantified variation in male courtship song and immunocompetence, and then examined female choice for different males
c) Juveniles were raised in isolation to ensure that all individuals tested were virgins
d) At maturity, the courtship song of each male was recorded and analyzed to quantify the rate of production and duration of HF and LF ticks
e) Immunocompetence was assayed by measuring cellular encapsulation rate, an immune system response in which a foreign antigen like a pathogen is surrounded with a capsule to kill it
f) The implant was removed and viewed under a microscope to quantify the degree of encapsulation: higher rates indicate higher immune system function
g) Placed a single female in a test chamber equidistant from two speakers that simultaneously played the courtship songs of two size-matched males, whose encapsulation rate (immunocompetence level) was known

43
Q

FIELD CRICKETS & GOOD GENES: Results

A

a) Females preferred males that produced a higher frequency and duration of HF ticks, these males also had higher encapsulation rates
b) Females preferred males producing the greatest expression of a costly secondary trait (HF tick production) and these males also had high immune system function
c) Encapsulation ability is heritable in insects, suggesting that by preferring males with high HF tick rates and durations, females can obtain indirect genetic benefits for their offspring

44
Q

Research 12.3: Mate Choice Fitness Benefits in Spiders

A

a) In many invertebrates, chemical signals or pheromones are commonly used in species recognition but less is known about their role in mate choice, however, pheromone production is costly and so may be a sexually selected trait that advertises quality
b) Sitting spiders expel a sticky substance when catching prey
c) Males provide no resources to females and are ideal for investigating the indirect fitness benefits of mate choice

45
Q

SPIDERS & MATE CHOICE BENEFITS: Research Question

A

What is the importance of pheromones as signals of male quality in mate choice?

46
Q

SPIDERS & MATE CHOICE BENEFITS: Methods

A

a) They collected juveniles from two sites in Singapore and raised them individually until they matured
b) They used virgins
c) Conducted a two-phase mate choice experiment using a Y-shaped apparatus to test female choice for both live males and male pheromones alone
d) First phase; two males were placed behind mesh screens, the screen prevented visual contact but allowed chemical communication
e) Females were given one hour to select a mate; selection was determined by the female making contact with a screen for a minute
f) Second phase; collected silk draglines and chemicals and placed these filter papers behind the mesh screens

47
Q

SPIDERS & MATE CHOICE BENEFITS: Results

A

a) Of the 44 females that selected a male in the first phase, 42 selected the same male’s filter paper in the second phase, meaning females can use male pheromones to select a mate
b) The 42 females that chose a mate in phase 2 were divided into two treatments, so mean weight of females in either group was similar
c) One set was allowed to mate with their preferred male but the other was restricted to mating with their non-preferred male
d) Females mated to their preferred male produced significantly larger eggs sacs with more and heavier eggs, and recorded a higher hatch rate
e) This suggests that male pheromones may function as if they convey information about male size, nutritional status, immune function, fertility, or other attributes

48
Q

Research 12.4: Mate Guarding in Warblers

A

a) Mate Guarding: a behaviour in which a male remains close to his mate to prevent her from mating with rivals
b) However, the time and energy spent guarding one mate can prevent a male from mating with other females or acquiring other food and resources
c) A single pair of Warblers will mate and raise offspring together, but females will often mate with other males so males risk raising another male’s offspring, called extra-pair young: offspring of a pair-bonded female produced outside the pair bond by a third-party male

49
Q

WARBLERS & MATE GUARDING: Research Question

A

How effective is mate guarding?

50
Q

WARBLERS & MATE GUARDING: Methods

A

a) Followed focal males and their mates for up to an hour on days just before egg laying
b) Every 2 minutes, they recorded distance between individuals and noted how often males followed females or vice versa
c) Evidence of effective mate guarding would be short inter-individual distances and a lot of of male rather than female follows
d) Collected blood samples from all nestlings for genetic analysis to determine parentage

51
Q

WARBLERS & MATE GUARDING: Results

A

a) Males that spent more time mate guarding had fewer extra-pair young than those that spent less time mate guarding (as measured by male follows and time spent within 20m of the female)
b) The paternity of treatment and control birds, birds who spent no time mate guarding and those that could, were compared
c) The nests of males that had been away from their mate for one hour contained extra pair-young, while only 50% of control nests contained pair-young
d) Conclusion: mate guarding can be an effective strategy for increasing paternity assurance and thus fitness for males BUT mate guarding does not prevent females from mating with other males

52
Q

Research 12.4: Sperm Competition in Tree Swallows

A

a) Another way a male can reduce mate competition to enhance his likelihood of success when sperm competition occurs is to swamp a rival male’s sperm by mating frequently with a female

53
Q

TREE SWALLOWS & SPERM COMPETITION: Hypothesis

A

Frequent copulation with a female mate will enhance male fitness in tree swallows

54
Q

TREE SWALLOWS & SPERM COMPETITION: Methods

A

a) In tree swallows, copulations occur mainly at the nest site and so are relatively easy to observe, males hover over females and make cloacal contact
b) Previous work has shown that most fertilizations results from copulations that occur during the three days before egg laying
c) Beginning 9 days before egg laying, 43 focal pairs were observed for three hours a day over two weeks, starting at dawn when most copulations occur

55
Q

TREE SWALLOWS & SPERM COMPETITION: Results

A

a) Copulation rate varied among pairs and peaked in the three days prior to egg laying, averaging five copulations per hour
b) 52% of young were sired through extra-pair copulations
c) However, an increase in the frequency of copulations by a male increased the percentage of young he sired, as predicted
d) Conclusion: males can reduce the likelihood of paternity loss from sperm competition by increasing their copulation frequency

56
Q

Cryptic Female Choice

A

a) A situation that occurs when a female influences the fertilization success of sperm from one male over that from others
b) Can females affect the fertilization probability of sperm from males that differ in degrees of relatedness?

57
Q

Research 12.4: Inbreeding Avoidance via Cryptic Female Choice in Spiders

A

a) Females occupy webs that are visited by roving males and commonly mate with two males
b) Each female contains two independent sperm storage organs, and these SPERMATHECAE, are filled as a result of two separate matings, either by the same male or two different males
c) They inseminate females using their paired pedipalps which are filled with sperm but use only one pedipalp per mating attempt
d) The right pedipalp of a male is always inserted into the right spermathecae of a female, and vice versa

58
Q

SPIDERS & INBREEDING AVOIDANCE: Research Question

A

Do female orb spiders avoid inbreeding depression by cryptic female choice?

59
Q

SPIDERS & INBREEDING AVOIDANCE: Methods

A

a) Conducted double mating trials: females were mated with either (1) two sibling males (SS), (2) two non-sibling males (NN), or (3) a sibling and non-sibling male (SN or NS)
b) They removed one pedipalp of each pair so they had complementary pairs
c) Males and females were separated until adulthood, females were placed in individual containers where they built a web and males were kept in separate containers
d) Males were introduced one at a time, allowed up to one hour of copulation, and then removed
e) After both copulated, they estimated the number of sperm transferred to each spermathecae by counting the spermatozoa under a microscope after sacrificing the female spiders
f) They counted the proportion of eggs fertilized by each of the two males

60
Q

SPIDERS & INBREEDING AVOIDANCE: Results

A

a) Females mated readily with both siblings and non-siblings
b) Females stored more sperm from the non-sibling than they did from the sibling
c) The proportion of eggs fertilized by the non-sibling second male was higher as well (75% vs 48%)

61
Q

Research 12.5: Conditional Satellite Males in Tree Frogs

A

a) Females prefer to mate with males that produce the most energetic calls (loudest and at the highest rate) and calls of the lowest frequency (typically only large males can produce the lowest-frequency sounds)
b) Male tree frogs exhibit both a bourgeois calling tactic and a parasitic satellite tactic

62
Q

TREE FROGS & SATELLITE MALES: Predictions

A

(1) Males differ in attractiveness to females and those that produce unattractive calls are more likely to be satellites
(2) Satellite males should exhibit the same call preference as females, both should be attracted to males that exhibit the lowest-frequency calls

63
Q

TREE FROGS & SATELLITE MALES: Methods

A

a) Recorded 20 consecutive calls and then captured, measured, and marked each male
b) To obtain calls from satellite males, they removed the nearest caller, which induced the satellite to begin calling
c) Found that bourgeois calling males were larger, in better condition, and produced lower-frequency calls than satellites
d) Created a pair of synthesized calls, one of which has a lower bottom frequency
e) Both females and satellites both strongly prefer male calls with the lowest frequencies

64
Q

Research 12.5: ESS & Sunfish Sneaker Males

A

a) Some male sunfish, called parentals (those who adopt a bourgeois tactic), defend nests in breeding territories and provide parental care for eggs there
b) Females approach these males and spawn at a nest site within the territory
c) Parasitic sneaker males do not defend territories but instead intrude while a parental male is spawning with a female in an attempt to fertilize eggs as they are laid

65
Q

SUNFISH SNEAKER MALES & ESS: Research Question

A

What is the reproductive success of parental and sneaker male pumpkinseed sunfish?

66
Q

SUNFISH SNEAKER MALES & ESS: Methods

A

a) When a spawning event occurred, they captured nesting males, females, any sneakers involved in the spawning attempt, and all subsequent developing eggs

67
Q

SUNFISH SNEAKER MALES & ESS: Results

A

a) Found that sneaker males were younger and smaller than parentals; most sneaker males were about two years old while parental males were at least four years old
b) On average, parental males sired about 85% of the offspring in their nest, and sneakers sired 15%
c) Estimated that sneaker males represent only about 15% of the population
d) Since the reproductive success of sneakers is in proportion to their abundance in the population, the two strategies actually have equal reproductive fitness

68
Q

SUNFISH SNEAKER MALES & ESS: Conclusion

A

a) The two strategies are in an ESS (Evolutionary Stable Strategy)
b) They found that parental and parasitic males exhibited different hormone profiles
c) Parasitic sneaker males had higher testosterone and cortisol and lower 11-keto-testosterone levels, suggesting that hormones may regulate the adoption of different reproductive tactics in sunfish

69
Q
A
70
Q

GUPPIES & MATE COPYING: Research Question

A

Do females copy the mate choice of other females?

71
Q

GUPPIES & MATE COPYING: Methods

A

a) Placed a focal female in a clear Plexiglas container in the centre of the aquarium
b) Placed malls, matched for size and colouration, into chambers on either side of the aquarium
c) Allowed a focal female to choose a male
d) The amount of time the female spends near the male is a good indicator of mate preference
e) Then, he arranged the aquarium so that a different female was now near the non-chosen male, this was done to stimulate her “choosing” this male as a mate
f) The model female and male interacted with typical courtship behaviours, which the focal female could view
g) Then, the model was removed and the focal female was released and allowed to swim freely for ten minutes

72
Q

GUPPIES & MATE COPYING: Results

A

a) Of 20 focal females, 17 spent significantly more time next to the male that had been near the model female
b) These females switched their mate choice preference to copy the mate choice of the model female
c) Mate choice is not always independent, instead, females will copy the mate choice of others they observe

73
Q

Research 12.6: Mate Copying in Fruit Flies

A

a)

74
Q

FRUIT FLIES & MATE COPYING: Research Question

A

What factors affect the mating behaviour of female fruit flies?

75
Q

FRUIT FLIES & MATE COPYING: Hypothesis

A

Observations of the mating decisions of others will affect the mating decisions of female fruit flies

76
Q

FRUIT FLIES & MATE COPYING: Methods

A

a) Created groups of high-quality males (fed nutrient-rich food) and low-quality males (fed nutrient-poor food)
b) Conducted a female mate choice trial with one high and one low quality male
c) Allowed half the females to observe a model female next to the high quality male while the other half observed a female next to the low-quality male
d) Repeated the mate choice trials

77
Q

FRUIT FLIES & MATE COPYING: Results

A

a) In the pre-test, females spent significantly more time near the high-quality male
b) In the post-test, females that observed a model female with the low-quality male now spent more time near the low-quality male

78
Q

T or F: in guppies, females prefer males with the most orange colouration and females mate copy when males are closely matched for colour, when it’s hard to distinguish differences. However, when males are very different in colour, female copying is rarely observed, also, young females should mate copy more often than older females

A

True

79
Q

Research 12.6: Non-independent Mate Choice by Male Mosquitofish

A

a)

80
Q

MOSQUITOFISH & MATE CHOICE: Research Question

A

Does the risk of sperm competition affect mate choice in male eastern mosquitofish?

81
Q

MOSQUITOFISH & MATE CHOICE: Methods

A

a) Three-stage experiment
b) 1st Stage: examined preference of focal males for two randomly selected females
c) 2nd Stage: focal male was constrained and a rival male was placed next to each female, half the focal males saw a rival near the female he preferred in the first phase but others saw a rival only next to the un-preferred female
d) 3rd Stage: rivals were removed and the focal male was allowed to associate with both females again

82
Q

MOSQUITOFISH & MATE CHOICE: Results

A

a) Males consistently preferred the same, larger female in stages 1 and 3 after observing a rival near their un-preferred female
b) Males that observed a rival near their preferred female in stage 2 tended to spend less time near that female in stage 3
c) Males have a mating preference for larger females and their preference of mates is influenced by observing the choice of other males
d) They spend less time near a preferred female if they have just seen her associate with another male

Life Sci 2D03 (7 decks)

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