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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
Who came up with the Parental Investment Theory?
Robert Trivers (1972)
26
What did Trivers come up with?
PIT (Parental Investment Theory)
27
Parental Investment Theory
- 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
Fitness of males is limited by...
Access to fertilizable gametes (female eggs)
29
Fitness of females limited by...
Access to resources to produce eggs
30
Limiting factor for males leads to...
competition among males for mates (male-male competition)...intrasexual
31
Limiting factor for females leads to...
Choosing best mate out of all males (female choice)...intersexual
32
2 selection pressures of sexual selection?
1. Male-male competition | 2. Female choice
33
Limitations of the Parental Investment Theory
Based only on investment into gametes, not post-fertilization investment
34
Strong sexual selection on... | Week sexual selection on...
Males (# mates correlates with reproductive success) | Females (# mates do not directly correlate w/ reproductive success)
35
Is reproductive potential higher in men or women?
Men; women are limited by resources
36
What are the 2 forms of intrasexual selection?
1. Pre-copulatory | 2. Post-copulary
37
Pre-copulatory competition
Number of copulations
38
Post-copulatory competition
Sperm competition; this male's sperm actually fertilizes the egg
39
Examples of pre-copulatory competition
- Fights - Territory claims - Social status (dominance in herds)
40
Examples of post-copulatory competition
Sperm competition
41
Social status in walrus
Male herds establish dominance. Most dominant one gets to woo females first.
42
Elephant seals compete via...
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
Examples of sperm competition
- Mate guarding - Sperm removal - Copulation duration - Sperm plugs - Traumatic insemination - Anti-aphrodisiacs
44
Mate guarding
Stay with female until she uses your sperm to fertilize her egg
45
Sperm removal
Remove other sperm in female before inserting yours
46
Copulation duration
Increase amount of sperm transferred
47
Sperm plugs
After 1 insemination, secretions in sperm form plug to block female reproductive tract (other males can't access)
48
Traumatic insemination
Male pierce through female abdomen & inject sperm into hemolymph -> travels to ovaries and fertilize there
49
Anti-aphrodisiacs
Scent the females to signal to other males she has already been mated (others stay away)
50
Mate guarding in shrimp thingy (celus?)
Guard female pre-mold, mate with her as she begins to mold. Once female molds/hardens, she can't be inseminated again.
51
Mate guarding in damselflies
- 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
Mate guarding in birds
Male guard female from other males that may try to get with her
53
Examples of organisms that use copulation duration
- Dung flies | - Water striders
54
Purpose of copulation duration
- Guard from other matings | - More sperm transfer
55
Examples of organisms that use sperm removal
Damselflies
56
Features of sperm removal orgain
Inflated horn Whip Barbs
57
Frequency dependent selection
fitness of a phenotype depends on others in the population
58
What alternative reproductive strategy does bluegill sunfish use?
Satellite (male) pretends to be female, and fertilizes female without parental male noticing. Sneaker (male) hides until female lays eggs, fertilizes, then runs.
59
What are the strains of bluegill sunfish?
Parental male Cuckolder male (sneaker -> satellite) Female
60
Examples of species that use alternative reproductive strategies
- Bluegill sunfish
61
Example of frequency dependent selection
Side-blotched lizards (orange, blue, yellow)
62
Why is there not one best strategy for male selection strategies?
Frequency selection: "best" phenotype depends on frequency of other phenotypes in the population e.g. side-blotched lizards
63
Orange lizards
- Defend large territories (lots of females) - Aggressive towards all males - Can't tell difference b/t yellow and females
64
Blue lizards
- Defend smaller territories (focus on 1-2 females) | - Can tell difference b/t yellow and females
65
Yellow lizards
- Pretends to be females in orange territory
66
Side-blotched lizards relationship
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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