Evolution of Sex Flashcards

1
Q

Whiptail Lizards’ Reproduction

A

Some whiptail lizard species reproduce through parthenogenesis, where females clone themselves without male fertilization. Offspring are genetically identical to the mother, maintaining population continuity without sexual reproduction

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2
Q

Prevalence of Sexual Reproduction

A

Sexual reproduction promotes genetic diversity, improving populations’ adaptability to changing environments and resilience against parasites, diseases, and environmental pressures

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3
Q

Disadvantage of Asexual Reproduction

A

Asexual reproduction limits genetic diversity, making populations more vulnerable to environmental changes, diseases, and evolutionary stagnation

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4
Q

Red Queen Hypothesis

A

This hypothesis suggests that organisms must constantly evolve to maintain their fitness relative to co-evolving species like parasites, predators, or competitors

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5
Q

Robert Vrijenhoek’s Topminnow Experiment

A

Initially, sexual topminnows in a third pond were highly susceptible to parasitic flukes due to low genetic diversity from the founder effect. Vrijenhoek introduced genetically diverse sexual fish, increasing resilience against parasites

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6
Q

Differences Between Eggs and Sperm

A

(1) size: eggs are large and nutrient-rich; sperm are small and mobile, (2) production: few eggs vs. millions of sperm, (3) motility: sperm are motile; eggs are stationary, and (4) energy investment: eggs require more energy to produce; sperm are energetically cheap

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7
Q

Evolution of Peacocks’ Tails

A

Magnificent tails evolved through intersexual selection, as females prefer larger, more colorful tails, signaling health and genetic fitness

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8
Q

Darwin and Peacock Tails

A

Darwin was initially puzzled by peacocks’ tails because their extravagant features seemed to hinder survival, contradicting natural selection

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9
Q

Intersexual Selection

A

Female mate choice for traits like plumage or songs

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10
Q

Intrasexual Selection

A

Male competition for mates through dominance or territory control

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11
Q

Peacock Tail Experiment

A

Peacocks with fewer eyespots on their tails had reduced mating success, highlighting the importance of tail display in sexual selection

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12
Q

Female Caution in Mate Choice

A

(1) High reproductive investment (e.g., pregnancy, offspring care), (2) limited reproductive opportunities, and (3) desire for high-quality genes or resources from mates

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13
Q

Purpose of a Rooster’s Comb

A

The comb signals health and vitality, attracting hens by indicating strong genetics and overall fitness

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14
Q

Hen’s Response to Subdominant Roosters

A

Hens can eject sperm from subdominant roosters post-mating, favoring dominant males’ genetic contribution

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15
Q

Male Damselfly Behavior

A

Before insemination, male damselflies use specialized anatomy to remove sperm from previous mates, increasing their reproductive success

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16
Q

Australian Redback Spiders’ Mating Ritual

A

Males perform somersaults into the females’ jaws during mating, often sacrificing themselves to ensure successful fertilization

17
Q

Advantages of Redback Spiders’ Behavior

A

(1) Extended copulation increases paternity likelihood and (2) consumed males provide nourishment, enhancing females’ reproductive success

18
Q

Male Fruit Fly Semen Effects

A

(1) Reduces female receptivity to future mating, (2) enhances egg production, and (3) shortens females’ lifespan, reducing competition for offspring

19
Q

IGF2 Protein in Mice

A

Insulin-like Growth Factor 2 (IGF2) promotes fetal growth and is paternally inherited, enhancing offspring survival

20
Q

Seychelles Warbler Mothers

A

Females can manipulate offspring sex ratios, producing daughters in high-quality territories where survival likelihood is higher

21
Q

Infanticide by Male Lions

A

New males kill existing cubs to induce estrus in females, allowing them to pass on their genes more quickly

22
Q

Worker Bees’ Sacrifice

A

Worker bees forgo reproduction to support the hive, promoting shared genetic success through kin selection

23
Q

Social Insect Colony Ratios

A

A 3:1 female-to-male ratio results from haplodiploid reproduction, maximizing colony efficiency and genetic output

24
Q

Marion Petrie’s Peacock Research

A

Marion Petrie removed peacocks from their leks and raised their offspring in isolation. When the offspring were later introduced to a lek, they naturally associated with their brothers and half-brothers, demonstrating a genetic basis for lek behavior and social cohesion

25
Q

Chimpanzee vs. Bonobo Societies

A

Chimpanzees: male-dominated, hierarchical, aggressive, with frequent infanticide
Bonobos: female-led, peaceful, cooperative, with no infanticide

26
Q

Ecological Factors in Bonobo Behavior

A

Dense, resource-rich jungles with minimal competition allowed females to form alliances and prioritize non-aggressive males

27
Q

Intersexual Selection in Bonobos

A

Female choice for cooperative, peaceful males shaped bonobo behavior, reducing male aggression over generations

28
Q

Ecological Factors in Chimpanzee Behavior

A

Resource scarcity and competition with gorillas promoted male dominance and aggression in chimpanzees

29
Q

Intrasexual Selection in Chimpanzees

A

Aggressive male competition for dominance and mates reinforced traits like strength and hierarchical control