Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genetics and Evolution > Lecture 18 - Sexual Selection > Flashcards

Lecture 18 - Sexual Selection Flashcards

1
Q

What is reproduction?

A

The production of offspring.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is sex in biological terms?

A

The combining and mixing of genes, often through gamete fusion from different individuals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the primitive state of reproduction?

A

Asexual reproduction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How often has sexual reproduction evolved, and what example exists of its loss?

A

It may have evolved once but has been lost many times, such as in Bdelloid rotifers, which have not had sex for 80 million years.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the “two-fold cost of sex”?

A

In sexually reproducing species, the population does not double each generation due to shared genetic information and unequal contribution by sexes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Do sexual reproduction and sexes always coexist?

A

No, organisms like Chlamydomonas produce equal-sized gametes and do not have distinct sexes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is required for sexual selection to occur?

A

Distinct sexes within the population.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why do males and females often look and behave differently?

A

Due to sexual selection.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is sexual selection?

A

A subset of natural selection acting on traits that provide a mating advantage rather than direct survival benefits.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is sexual selection predominantly seen in males?

A

Males often experience strong selective pressure to increase mating success, while females invest more in offspring and are choosier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does differential parental investment affect sexual selection?

A

The sex investing less in offspring is subject to strong sexual selection and competes more, while the other is choosier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the characteristics of species with equal parental investment?

A

There is no sexual selection as both parents contribute equally.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens in species with unequal parental investment?

A

Sexual selection occurs, favouring traits that enhance mating success in the less investing sex.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why might any mutation in males conferring a mating advantage spread faster?

A

Males are often under stronger sexual selection pressure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the physical traits selected in intra-sexual selection?

A

Size and weaponry.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What physiological trait is selected in intra-sexual selection?

A

Sperm production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the behavioural outcome of intra-sexual selection?

A

More competitive individuals (usually males) have increased fitness.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens during pre-copulation intra-sexual selection?

A

Males compete, with larger size discrepancies leading to more mating opportunities (e.g., Northern elephant seals).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the costs of antlers in red deer?

A

Antlers are re-grown each year, which is energetically costly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens in post-copulation intra-sexual selection?

A

Sperm competition, mate guarding, mate manipulation, and infanticide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does sperm competition involve?

A

Producing more sperm to outcompete others (e.g., Soay sheep).

22
Q

What unique sperm competition strategy is used by damselflies?

A

Damselfly males use spikes to remove sperm from other males.

23
Q

What is mate guarding?

A

Physically guarding the female, extending copulation, or using copulatory plugs.

24
Q

How do male fruit flies manipulate females during mating?

A

They pass proteins that increase oviposition, reduce re-mating, and remove sperm from other males.

25
Q

What are the traits selected in inter-sexual selection?

A

Epigamic characters like behaviour and ornamentation.

26
Q

How did Malte Andersson study mate choice in widowbirds?

Why don’t all males have long tails?

A

By manipulating tail lengths and observing female preferences.

Longer tails may increase attraction but come with fitness costs.

27
Q

What evidence supports mate choice in stalk-eyed flies?

A

Females prefer males with longer eye stalks, which also helps in competitions.

28
Q

Why does mate choice happen?

A

Due to direct benefits (e.g., food, protection) and honest signalling (e.g., better genes).

29
Q

What is Fisher’s runaway sexual selection?

A

A process where a trait and preference for it co-evolve, leading to exaggerated traits (e.g., “sexy sons”).

30
Q

What challenge does sensory bias pose in Tungara frogs?

A

Male calls attract both females and predators (e.g., white-lipped bats).

31
Q

What role are flatworms fighting to carry out in Pseudoceros bifurcus?

A

The male role, as sperm is cheap to produce.

32
Q

In Mormon crickets, which sex competes and which is choosy?

A

Males compete; females are choosy.

33
Q

How does sexual selection operate with unequal parental investment?

A

The sex investing less experiences stronger selective pressure to maximise mating success.

34
Q

Why are there small-testes males?

A

Physiological limits mean smaller-testes males eventually get mating opportunities.

35
Q

What does frequency-dependent selection explain in side-blotched lizards?

A

The most competitive male morph changes depending on its frequency in the population.

36
Q

Why don’t all individuals have attractive traits?

A

Due to costs (e.g., energy, predation) and different hormone levels.

37
Q

How do guppies adapt in the presence of predators?

A

With high predation, they have fewer, smaller, iridescent spots; without predators, they develop larger, brighter spots.

38
Q

Do humans experience sexual selection?

A

Possibly, with traits like dancing ability being indicators of mate quality.

39
Q

Why does sexual selection occur more strongly in one sex than the other?

A

Sexual selection occurs more strongly in the sex with lower parental investment because they have more to gain by increasing mating opportunities, while the other sex is more selective due to higher investment in offspring.

40
Q

How does Fisher’s runaway selection differ from direct and honest signalling?

A

Fisher’s runaway selection can become self-perpetuating without direct or indirect fitness benefits, whereas direct benefits provide tangible advantages (e.g., food or protection) and honest signalling indicates genetic quality.

41
Q

Why might males with exaggerated traits like long tails or bright colours not always be favoured in a population?

A

These traits are often costly to maintain and can increase predation risk, creating a balance between sexual attractiveness and survival.

42
Q

What is the significance of sensory bias in sexual selection? Provide an example.

A

Sensory bias occurs when preferences for certain traits evolve due to pre-existing sensory sensitivities. For example, male túngara frogs produce calls that attract females but also predators like white-lipped bats.

43
Q

How does sperm competition drive post-copulation sexual selection?

A

Sperm competition favours traits like increased sperm production, mate guarding, and mechanisms to remove or outcompete rival sperm, as seen in damselflies with specialized structures.

44
Q

How do mate guarding and mate manipulation differ as strategies in post-copulation sexual selection?

A

Mate guarding involves physical or behavioural strategies to prevent other males from mating, while mate manipulation alters female behaviour or physiology (e.g., proteins in male fruit flies).

45
Q

Why do small-testis males still exist despite the advantage of larger testes in sperm competition?

A

Physiological limitations and trade-offs in energy allocation ensure that not all males can maximize testis size.

46
Q

Why is there a balance between the size and number of gametes produced in sexually reproducing species?

A

Larger gametes provide more resources for offspring survival but are costly to produce, while smaller gametes can be produced in greater numbers to increase fertilization chances.

47
Q

Why is sexual selection described as a subset of natural selection?

A

It focuses specifically on traits that increase mating success rather than overall survival, driven by competition and mate choice.

48
Q

How do honest signals benefit offspring in sexual selection?

A

Honest signals, like the size of a peacock’s eye spots, indicate genetic quality, improving offspring viability and fitness.

49
Q

How do environmental factors influence sexual selection traits, such as guppy spots or deer antlers?

A

Traits evolve based on environmental pressures like predation (guppy spots) or competition (antler size), balancing attractiveness and survival.

50
Q

Why might inter-sexual selection lead to “sexy sons” but not always better survival traits?

A

Traits favoured in mate choice may increase mating success without directly improving survival, as seen in Fisher’s runaway selection.

Genetics and Evolution (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions