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BIO220 > BIO220 Lecture 2 > Flashcards

BIO220 Lecture 2 Flashcards

Why are the sexes different?

1
Q

What % of genes are shared b/t male and female?

A

90%

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2
Q

Despite sharing a large % of genes, why are male and females so different?

A

Difference in gene expression; transcribed differently (gonads, liver, brain…etc.)

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3
Q

What % of genes in fly are expressed differently between sexes?

A

50-90%

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4
Q

How many genes in fly genome?

A

13000

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5
Q

Dimorphism

A

Sexual differences - males and females act differently

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6
Q

Sexual dimorphism lead to the evolution of…

A

conspicuous ornaments and armaments

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7
Q

Conspicuous ornaments

A

Less obvious differences between males & females

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8
Q

Why do we care about conspicuous ornaments?

A

Evolutionary biologists interested in diversity b/t species; differences b/t male & female make up large portion of that difference.
(Difference b/t male-male & female-female small but male-female difference big.)

Same forces might be driving diversity between species.

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9
Q

Examples of species w/ conspicuous ornaments

A
  • Frigate bird

- Greater sage-grouse

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10
Q

Armaments

A

Features used in male-male competitions (mate competition)

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11
Q

Example of armaments

A
  • Stalk-eye flies
  • Elephant seals
  • Beetles
  • Deer antlers
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12
Q

How did Darwin explain some features of dimorphism?

A

(-) survival (due to increased predation)
(+) mating success

Natural selection AND sexual selection

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13
Q

Sexual selection

A

Advantage of certain individuals over other individuals in the same species & sex relative to reproduction.

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14
Q

Natural selection is made up of…

A
  • Survival

- Reproductive rate

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15
Q

Sexual selection is made up of…

A

Number of mates

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16
Q

Sexual selection is a subset of…

A

natural selection

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17
Q

Fitness in females

A
  • Reproductive rate (number of eggs produced over a period of time)
  • Survival (amount of time you produce eggs at that rate)
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18
Q

Fitness in males

A
  • Mating success (getting access to female eggs)

- Survivial

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19
Q

Fundamental difference between sexes?

A

Female produce few, huge gametes while males produce many, small ones
= anisogamy

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20
Q

Why are 2 sexes at all?

A

(FOUND IN READING)

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21
Q

Anisogamy

A

Unequal-sized gametes (between males and females)

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22
Q

How to determine if something was male / female?

A

Examine gametes.

  • Smaller gamete = male
  • Bigger gamete = female
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23
Q

Features of the egg

A
  • Resource rich
  • Few
  • Large
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24
Q

Features of the sperm

A
  • Inexpensive
  • Many
  • Small
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25
Q

Who came up with the Parental Investment Theory?

A

Robert Trivers (1972)

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26
Q

What did Trivers come up with?

A

PIT (Parental Investment Theory)

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27
Q

Parental Investment Theory

A
  • Sexes differ in their reproductive investment (females invest more)
  • Sex that invest less in offspring will compete intra-sex for the other sex
  • Other sex is the limiting factor
28
Q

Fitness of males is limited by…

A

Access to fertilizable gametes (female eggs)

29
Q

Fitness of females limited by…

A

Access to resources to produce eggs

30
Q

Limiting factor for males leads to…

A

competition among males for mates (male-male competition)…intrasexual

31
Q

Limiting factor for females leads to…

A

Choosing best mate out of all males (female choice)…intersexual

32
Q

2 selection pressures of sexual selection?

A
  1. Male-male competition

2. Female choice

33
Q

Limitations of the Parental Investment Theory

A

Based only on investment into gametes, not post-fertilization investment

34
Q

Strong sexual selection on…

Week sexual selection on…

A

Males (# mates correlates with reproductive success)

Females (# mates do not directly correlate w/ reproductive success)

35
Q

Is reproductive potential higher in men or women?

A

Men; women are limited by resources

36
Q

What are the 2 forms of intrasexual selection?

A
  1. Pre-copulatory

2. Post-copulary

37
Q

Pre-copulatory competition

A

Number of copulations

38
Q

Post-copulatory competition

A

Sperm competition; this male’s sperm actually fertilizes the egg

39
Q

Examples of pre-copulatory competition

A
  • Fights
  • Territory claims
  • Social status (dominance in herds)
40
Q

Examples of post-copulatory competition

A

Sperm competition

41
Q

Social status in walrus

A

Male herds establish dominance. Most dominant one gets to woo females first.

42
Q

Elephant seals compete via…

A

Territory; dominant male controls a beach that the females want to reproduce

Male that have access to beach protect & inseminate all females on that beach

43
Q

Examples of sperm competition

A
  • Mate guarding
  • Sperm removal
  • Copulation duration
  • Sperm plugs
  • Traumatic insemination
  • Anti-aphrodisiacs
44
Q

Mate guarding

A

Stay with female until she uses your sperm to fertilize her egg

45
Q

Sperm removal

A

Remove other sperm in female before inserting yours

46
Q

Copulation duration

A

Increase amount of sperm transferred

47
Q

Sperm plugs

A

After 1 insemination, secretions in sperm form plug to block female reproductive tract (other males can’t access)

48
Q

Traumatic insemination

A

Male pierce through female abdomen & inject sperm into hemolymph -> travels to ovaries and fertilize there

49
Q

Anti-aphrodisiacs

A

Scent the females to signal to other males she has already been mated (others stay away)

50
Q

Mate guarding in shrimp thingy (celus?)

A

Guard female pre-mold, mate with her as she begins to mold. Once female molds/hardens, she can’t be inseminated again.

51
Q

Mate guarding in damselflies

A
  • Male clasp females behind the neck until she lays eggs with his sperm (ovapositing)
  • Fly around to guard
  • Force her onto water, which expels eggs out of her
52
Q

Mate guarding in birds

A

Male guard female from other males that may try to get with her

53
Q

Examples of organisms that use copulation duration

A
  • Dung flies

- Water striders

54
Q

Purpose of copulation duration

A
  • Guard from other matings

- More sperm transfer

55
Q

Examples of organisms that use sperm removal

A

Damselflies

56
Q

Features of sperm removal orgain

A

Inflated horn
Whip
Barbs

57
Q

Frequency dependent selection

A

fitness of a phenotype depends on others in the population

58
Q

What alternative reproductive strategy does bluegill sunfish use?

A

Satellite (male) pretends to be female, and fertilizes female without parental male noticing.

Sneaker (male) hides until female lays eggs, fertilizes, then runs.

59
Q

What are the strains of bluegill sunfish?

A

Parental male
Cuckolder male (sneaker -> satellite)
Female

60
Q

Examples of species that use alternative reproductive strategies

A
  • Bluegill sunfish
61
Q

Example of frequency dependent selection

A

Side-blotched lizards (orange, blue, yellow)

62
Q

Why is there not one best strategy for male selection strategies?

A

Frequency selection: “best” phenotype depends on frequency of other phenotypes in the population

e.g. side-blotched lizards

63
Q

Orange lizards

A
  • Defend large territories (lots of females)
  • Aggressive towards all males
  • Can’t tell difference b/t yellow and females
64
Q

Blue lizards

A
  • Defend smaller territories (focus on 1-2 females)

- Can tell difference b/t yellow and females

65
Q

Yellow lizards

A
  • Pretends to be females in orange territory
66
Q

Side-blotched lizards relationship

A

Orange beat blue
Blue beat yellow
Yellow beat orange

Increase of blue -> increase orange
Increase yellow -> increase blue
Increase orange -> increase yellow

CYCLES

BIO220 (24 decks)

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