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From Organisms to Ecosystems - Lectures > Lecture 13. Evolution of Sex and Sexual Selection > Flashcards

Lecture 13. Evolution of Sex and Sexual Selection Flashcards

1
Q

What were Darwins two worries about natural selection ?

A
  1. Altruism

2. Sexual selection

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2
Q

What are the two problems with sex ?

A
  1. How could sexual reproduction evolve in the first place

2. How such mal-adaptively showy males could evolve

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3
Q

Does asexual or sexual reproduction get the most genes into the next generation ?

A

Asexual

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4
Q

Does asexual or sexual species populate a new environment more quickly ?

A

Asexual - sexual needs a mate

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5
Q

What was John Maynards Smiths idea called ?

A

The two fold cost of sex

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6
Q

What is the two fold cost of sex ?

A

Sexual reproduction is less efficient as

  1. only half the individuals genes are present in each offspring
  2. males dont produce offspring directly
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7
Q

What are some other negatives to sexual reproduction mentioned by John Maynard Smith ?

A
  1. Courtship and mating takes times, energy and is dangerous
  2. Finding a mate of the right age, species, sexual state can be difficult
  3. Courtship is showy which attracts predators and takes time
  4. Letting another individual that close carries danger or parasites and disease as well an injury
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8
Q

What are the advantages of sexual reproduction at an individual level ?

A

More variation in offspring leads to:

  1. Sibling competition reduced
  2. Better protection against predators
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9
Q

What are the advantages of sexual reproduction at a population level ?

A
  1. Mullers ratchet
  2. Hill Robertson Effect
  3. Sexual species survive longer
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10
Q

What is sexual reproduction at an individual level necessary for ?

A

Evolution of sex

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11
Q

What is sexual reproduction at a population level necessary for ?

A

Help with maintenance but not original evolution of sex

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12
Q

Why do we need to consider individual benefits not population ones when explaining the evolution of sex ?

A
  1. Evolution depends on selection between individuals
  2. The first mutant from asexual to sexual had to outcompete the asexuals in the population
  3. Benefits only obtained by the population wouldn’t spread a new allele for sex at the expense of the asexual alleles
  4. Its not for the good of the population that traits evolve
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13
Q

Why do aphids switch from being asexual to sexual just before winter ?

A

Future conditions are uncertain so variable offspring are a good bet

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14
Q

When do asexual produced offspring do well ?

A

When environment is stable

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15
Q

What does increase variation mean for siblings ?

A

Reduced competition meaning offspring survive in many different habitats and offspring compete less as fewer in any one patch

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16
Q

What was better protection against parasites also called ?

A

Red Queen Hypothesis

17
Q

What is the red queen hypothesis ?

A

Evolutionary arms race between hosts and parasites which sexual reproduction can help the hosts win

18
Q

What is the benefit to the individual parent concerning red queen hypothesis ?

A

Relief from parasites for some offspring, at least briefly

19
Q

What is Miller’s Ratchet ?

A

Gradual accumulation of deleterious mutation

20
Q

What does Mullers Ratchet effect

A

Asexual reproduction

21
Q

What is the Hill Robertson effect ?

A

Getting multiple mutation into one individual is easier in sexuals

22
Q

What species survive longer ?

A

Sexual

23
Q

What are the two types of sexual selection ?

A
  1. Intersexual

2. Intrasexual

24
Q

What is inter sexual selection ?

A

Female choice

25
Q

What is intra sexual selection

A

Male - male competition

26
Q

What is the result of inter sexual selection ?

A

Ardent males and reluctant females

27
Q

What does honest mean ?

A

Anything difficult for poor quality, sickly males to maintain

28
Q

What does female choice create ?

A

A directional selection pressure towards even bigger and more costly displays in males

29
Q

What are the two theories to explain extreme males ?

A
  1. Fishers Run Away Process

2. Zahavis’ Handicap Principle

30
Q

What is fishers run away process ?

A

The trait will continue until the detrimental effect is so strong that the extra chance of breeding is not enough to make it up

31
Q

Why dont females stop preferring extreme males ?

A

Sexy sons hypothesis

32
Q

What is Zahavi’s handicap principle ?

A

Male is displaying uncheatable signal of good genes as he survived despite handicap of excessive tail

33
Q

What does evolution not produce ?

A

What is best for the species

34
Q

What does selection favour ?

A

Whoever breeds best and this does lead to mal-adaptively extreme results

From Organisms to Ecosystems - Lectures (37 decks)

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