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advanced higher biology > 2.4 > Flashcards

2.4 Flashcards

1
Q

Explain sexual dimorphism in vertebrate gametes…

A

in female gametes, large nutrient filled energy store, expensive to produce, limited number, produced infrequently, if fertilised leads to high cost for female
in male gametes, small, non nutrients, cheap production, constantly made throughout life

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2
Q

What is internal fertilisation?

A

process by which sperm and egg nuclei fuse inside the female

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3
Q

What is external fertilisation?

A

when fusion occurs outside the female

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4
Q

How does external fertilisation work?

A

large number of eggs/sperm released into water and fertilise in absence of parents, external water essential to prevent gametes drying and to provide medium for sperm

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5
Q

Why is courtship behaviour important in external fertilisation?

A

as timing is crucial to ensure mature sperm/ripe eggs meet

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6
Q

Why is environmental stimuli important in external fertilisation?

A

i.e. temperature or day length may cause individuals to release gametes at the same time

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7
Q

How can chemical signs be used in external fertilisation?

A

chemical signs from one individual releasing gametes may trigger gamete release in others

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8
Q

Explain internal fertilisation…

A

necessary where no external moisture is available
cooperative behaviour ultimately leads to sexual intercourse
requires highly advanced reproductive systems

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9
Q

What are the costs/benefits of internal fertilisation?

A

benefits
- increased chance of success
- fewer eggs needed
- offspring retained internally for protection/development
- higher offspring survival rate

costs
- mate must be located, requires energy
- requires direct transfer of gametes from one partner to another

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10
Q

What are the costs/benefits of external fertilisation?

A

benefits
- large number of offspring can be produced

costs
- many gametes predated or not fertilised
- no or limited parental care
- few offspring survive

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11
Q

Explain parental investment benefit and female costs…

A
  • parental investment costly by increase probability of production and survival of young
  • most animals, female give more parental investment than just an egg
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12
Q

What are female costs in mammals and non-mammals?

A

mammals
- uterus prolonged internal gestation
-lactation

non-mammals
- egg structure with food store

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13
Q

What is the r/k selection theory?

A

relates to selection of combinations of traits in an organism that depend on quantity and quality of offspring

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14
Q

What is r-selection?

A

the species focuses on increased quantity of offspring at expense of parental investment individually

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15
Q

What is k-selection?

A

reduced quantity of offspring corresponding with increased parental investment

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16
Q

When does r-selection tend to occur?

A

when environments are unstable where species not reached reproductive capacity

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17
Q

When does k-selection tend to occur?

A

in stable environments

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18
Q

What are characteristics of r species?

A
  • smaller
  • shorter generation time
  • rapid maturing
  • reproduce earlier in lifetime
  • limited parental care
  • most offspring do not reach adulthood
  • e.g. mice, rabbits, insects, cane toads, octopus, mass spawning organisms
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19
Q

What are characteristics of k species?

A
  • larger
  • live longer
  • mature more slowly
  • reproduce many times
  • relatively few larger offspring
  • high level of parental care
  • high probability of reaching adulthood
  • e.g. humans, humpback whale, elephants, some birds
20
Q

What are mating systems based on?

A

how many mates an individual has during one breeding season

21
Q

What is monogamy?

A

mating of a pair of animals in exclusion of all others

22
Q

What is polygamy?

A

individuals of one sex have more than one mate

23
Q

What is polygyny?

A

one male with multiple females

24
Q

What is polyandry?

A

one female with a number of males in the same season

25
Q

Give an example of monogamy…

A

most birds due to high parental care in feeding chicks, unlikely one parent could handle feeding and protecting alone

26
Q

Give an example of polygamy…

A

In mammals, female is often only food source fore young (milk), males role is to protect, therefore polygamy common with one male mating with multiple females in harem

27
Q

Why is the female reproductive strategy important?

A

there is much to lose if they choose the wrong male so they are selective with who they mate with

28
Q

What are certain criteria for females in mating?

A

physical features
- e.g. size, strength confer to dominance so better resources
behavioural features
- e.g. indicates willingness to invest, good parenting

29
Q

What do females do get alpha males?

A

they compete with other females

30
Q

What do females look for when searching for a male?

A

they gain little from multiple matings so search for quality not quantity, almost every reproductively capable female will find a mate

31
Q

What is the male reproductive strategy?

A

far less choosy, little to lose, everything to gain, get as many mating opportunities as possible, seek quantity and prefer superior female but are not choosy

32
Q

What is male reproductive success?

A

males compete vigorously with other males for access to fertile females, but success is very variable and a small number of males achieve many mating with many never mating at all

33
Q

Describe sexual dimorphism…

A

females generally have inconspicuous markings
males have more conspicuous markings, structures and behaviours resulting in males with:
- larger body size
- evolution of weapons in males for fighting other males for mate
- evolution of dramatic colours
- displays for courtship
can be reversed for some species

34
Q

When are males often smaller?

A

in species that travel long distances to find mates, smaller size advantage for speed and stealth

35
Q

Describe sexual dimorphism in angler fish…

A
  • display extreme dimorphism as males live an almost parasitic existence with and underdeveloped digestive system
  • upon finding mate, male fuses to female as a parasitic existence, taking more than just giving sperm
36
Q

What is male-male rivalry?

A

competition/rivalry sometimes determines which animals mate; fight for dominance, female access often using elaborate weapons; success through conflict (real or ritualised) increases access to females

37
Q

What are sneaker males? (satellite males)

A

some males successful as ‘sneakers’, strategy in which smaller males can access female partners avoiding altercations with dominant males
- e.g. cuttlefish males

38
Q

What does female choice involve?

A

involves females assessing ‘honest’ signals of male fitness, signals which don’t mislead a female into thinking he’s fitter than he actually is

39
Q

What do honest signals indicate?

A

favourable alleles to increase offspring fitness or low parasitic burden

40
Q

What do dishonest signals do?

A

they can be disruptive for population, reducing sexual signalling system effectiveness

41
Q

Explain the measuring of fitness?

A

measured or describe in terms of good genes and low parasite burden
fewer parasites suggest overall fitter population, less susceptible to infection

42
Q

What is lekking?

A

exhibited in some bird species
- males gather to display a lek where female choice occurs, there are both dominant and satellite males

43
Q

How are dominant males spotted in a lek?

A

dominant males occupy the centre, others around the edges
dominant males may be larger, have more vivid colouration or more elaborate displays

44
Q

What can successful courtship behaviour be a result of?

A

in birds and fish, could be due to species specific stimuli and fixed action pattern responses

45
Q

What are species specific stimuli?

A

may include giving off chemicals or making sounds or certain displays to stimulate mating

46
Q

What is a fixed action pattern?

A

instinctive behaviour occurring across majority of species, often seen during mating rituals

47
Q

Describe specific sign stimulus and FAPs in stickleback fish…

A
  1. female presents swollen belly to male (SS)
  2. male performs ‘zig zag’ dance (FAP and SS)
  3. female follows male (FAP and SS)
  4. male indicates nest to female (FAP and SS)
  5. female lays eggs (response)

advanced higher biology (17 decks)

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