Lecture 23-25: Mallon Flashcards Preview

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Flashcards in Lecture 23-25: Mallon Deck (50)
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1
Q

Define intrasexual selection:

A

Fighting between one sex (generally male) in order to drive off or kill others. - The other sex remains passive

2
Q

Define intersexual selection:

A

One sex attempts to entice to other sex which then selects their mate.

3
Q

Why is it usually males which undergo competition?

A

Isogamy has evolved into anisogamy. Smaller gametes need larger gametes to survive, however there is less selective pressure on big gametes to mate with big gametes (decreased cost) Smaller gametes evolve faster due to greater variation

4
Q

Define isogamy and anisogamy

A

Isogamy: One type of gamete with continuous variation Ansiogamy: different sized gametes - male and females

5
Q

Why is parental care female dominated?

A

Male fitness / success increases most with increased mating. Males do not want to care for offspring which may not be theirs (multiple paternity) Female success increases more with conversion of resources (eggs) to offspring –> invest more into one egg –> male competition

6
Q

Why does male competition lead to decreased parental care?

A

Successful males will be those which mate the most. Mate more = decreased chance of parental care

7
Q

Why do females choose over?

A

Good resources or good genes

8
Q

What resources do females pick over?

A

Male frogs fight over ponds to posses those of the best quality. The best ponds will attract the most mates.

9
Q

What do bower birds show about gene selection?

A

Build nests to attract female before then performing. Better displays –> increased mating - females want sons who are better at displays.

10
Q

Please describe fisherian runaway?

A

Females select male trait due to it indicating a pre-exisiting bias, which will be passed onto sons if it is heritable. Sons have an advantage –> increased chance of mating. Leads to a cycle / positive multiplier effect.

11
Q

Please explain the handicap principle?

A

Still survive with an exaggerated trait due to other physical advantages. Long tailed widow birds: - Females select for birds with longest tails due to possible fitness advantage. This has been proven by manipulation experiments, cutting off and increasing tail sized.

12
Q

How does sperm compete?

A

Different ejaculates compete for fertilisation. Females may mate multiply because ‘it is more effort to resist’, and may gain material benefits and or genetic benefits (spermatophore).

13
Q

What is female sperm choice and why is it important?

A

Females may secretly mate with ‘superior’ males but then use the inferior males for parental care. - In contrast males often advertise themselves to potential mistresses.

14
Q

When does sexual conflict occur?

A

When optimal outcome differs for males and females - mating conflict, fertilisation of ova, parental investment

15
Q

How can sexual conflict lead to an arms race?

A

Female water striders evolve to be spiny to force males off, in reply males evolve to be more ‘grippy’ –> exaggerated traits.

16
Q

How can males affect the success of other males?

A

Techniques or morphology to decrease success - Odonata males have hooks on penis to extract previous males sperm.

17
Q

Define parental care:

A

any form of parental care that is likely to increase the fitness of offspring

18
Q

Define parental expenditure:

A

expenditure of resources on the care of offspring by a parent

19
Q

Define: parental investment

A

parental behaviour that increases the fitness of offspring at the cost of decreased ability for parent to produce further offspring.

20
Q

What is pre-birth parental care?

A

Investment in gamete production - feeding to increase egg size. Preparation of natal environment- nests, burrows, territories Care and nutrition of embryos- placenta, incubation, guarding, carrying

21
Q

What is after-birth parental care?

A

Provisioning or protecting young - Supplying with food, lactation, moutbrooding Care following nutritional independence - support in conflict or feeding

22
Q

What sort of parental care is observed in terrestrial arthropods?

A

Uncommon but female > male (spiders and scorpions)

23
Q

What sort of parental care is observed in fish?

A

>25% of fish, Male > female (egg guarding, oral brooding, cleaning, fanning)

24
Q

What sort of parental care is observed in amphibians

A

18% of salamanders 6% frogs and toads Male or female (egg / tadpole attendance and transport, feeding).

25
Q

What sort of parental care is observed in reptiles

A

Uncommon but female > male Male and female crocs respond to hatchlings call, dig them up and bring them to water in their mouth.

26
Q

What sort of parental care is observed in birds?

A

Most species use both parents Male provisions female (egg laying and incubation, nest building and feeding)

27
Q

What sort of parental care is observed in mammals?

A

100% of parents - 100% females, 5% direct males Female- gestation, lactation Male - generally only cares in monogamous relationships (naked mole rat), feeding, transport, protection.

28
Q

Why is female care more common - investment hypothesis?

A

Females heavily invest in eggs Abandoning offspring is risky (depends on species)

29
Q

Why is female care more common - uncertain paternity hypothesis?

A

Female knows its theirs, male cant be sure. Male wouldnt gain anything from caring for other males offspring.

30
Q

Why is female care more common - order of gametes release hypothesis?

A

Internal fertilisation - females forced to invest, males can leave External fertilisation - female has an ability to desert Simultaneous release (fish) –> male care

31
Q

Why is female care more common- association hypothesis?

A

Females more likely to be present during critical times- egg laying, birth. Males are physically separated and may not be there.

32
Q

What are the proximate constraints on parental care- birds?

A

Internal fertilisation, egg incubation Main caring activity is feeding- two parents can provide twice as much food, and only one parent halves the reproductive output

33
Q

What are the proximate constraints on parental care - mammals?

A

Females cannot desert due to gestation and lactation Males cannot care directly, but can care for females Best option of increased reproduction would be desertion.

34
Q

What are the proximate constraints on parental care- fish?

A

-External fertilisation so females are not obliged to care -Non-telost fish –> internal fertilisation –> female care -Benefits of care for female and male the same but more costly for female as sperm are easier to produce (female needs to go and recover size to increase fecundity). - Male care leads to increased reproductive success (egg guarding –> other females laying eggs, but females lose more reproductive success) - Only one parent is needed: egg fanning and gaurding is divisible, doesnt matter if its 10 or 100 eggs).

35
Q

What are the benefits of parental care?

A

Having a mother may lead to less aggression and increased defence (ververt monkey). Leads to increased pregnancies and increased offspring survival.

36
Q

How costly is parental care and when should it be stopped?

A

Offspring wants as much as it can get from a parent but there comes a point where parents reproductive success will increase more by having further offspring. Balance of benefit and cost changes over time - when cost > benefits it should be stopped. -When the age of a parent increases, success of mating decreases and therefore more resources should be placed upon care.

37
Q

Define an ESS

A

An evolutionary sustainable strategy: a strategy which cannot be improved / beaten or cheated, within the current parameters.

38
Q

What factors affect an ESS?

A

-Probability of a brood suriving depends on parents Two parents > One parents > No parents (P2 > P1 > P0) - Probability of a male mating again = p - Deserting female lays W eggs, caring female lays w eggs. Would expect W>w

39
Q

What are the 4 ESS’s for parental care?

A

1- neither parent cares 2- male cares 3- female cares 4- both parents care

40
Q

What are the requirements for each ESS?

A

1- WP0 > wP1 AND P0(1+p) > P1 2- WP1 > wP2 AND P1 > P0(1+p) favoured when P2= P1 3- wP1 > WP0 AND P1(1+p) > P2 4- wP2 > WP1 AND P2 > P1(1+p) favoured if P2 >> P1

41
Q

Define: monogamy?

A

One male: one female (either for one breeding season or longer) - Both partners may forego extra mating or one of the pair may enforce monogamy - Generally leads to bi-parental care

42
Q

Define: polygyny?

A

One male: several females Defending females or resources they require. Attract females to a display site (like a lek) or by male searching –> maternal care.

43
Q

Define: polyandry?

A

Several males: one female, by defending them continously or in succession - often leads to paternal care

44
Q

Define promiscuity?

A

Both males and females have multiple partners

45
Q

Define polygamy?

A

When an individual has more than one mate

46
Q

Explain mating systems without male paternal care…

A
47
Q

What is the limit on female reproductive success?

A

Resources- females distribute themselves according to the resources

48
Q

What is the limit on male reproductive success?

A

Limited by the distribution of females –>go and search for females –> defend areas of resources

49
Q

Why does mating depending on resource distribution.

A

If area defended by a single male contains lots of females (resources are clumped) it is easier for him to monopolise an area in terms of females.

50
Q

How can you describe mating systems with male parental care?

A

Males are resources There may be a dominant male who is the father to the majority of offspring due to unfaithful females, despite the population appearing monogamous.