Natural Selection (2) Flashcards
What will we be reviewing: 5
1) Parental Investment (PI)
2) Different level of PI for males/females
3) Differences in potential reproductive output in XX & XY
4) The difference in Variances in fitness XX & XY
5) Difference factors limiting fitness for XX & XY
Note) Kin selection and reciprocal altruism explain
Altruism
Parental Investment explains?
Sex differences in behaviour (Morphology)
Parental Investment is NOT a reformation of Darwins Theory of Sexual Selection T or F?
FALSE - Parental Investment IS a reformation of Darwins Theory of Sexual Selection
Sexual Selection (3)
1) Proposed by Darwin
2) Explain Secondary Sexual Characteristics
3) Sexual Dimorphism
Sexual Selection - Darwin - Attributes secondary sexual characteristics to …..
sexual selection
What are secondary sexual characteristics? (2)
- Male / Female distinctions that appear at puberty.
- The distinction between men and female that go beyond reproductive differences
- ex) larger teeth, difference size, coloration
Why was another mechanism needed to explain these features - Secondary Sexual Characteristics
ARE NOT easily explained by NATURAL SELECTION
1) Not beneficial to survival
2) Are sometimes detrimental to the survival
3) Don’t appear until puberty - can’t be part of the competition for survival to adulthood
According to Darwin, Secondary Sexual Characteristics evolved due to (3)
1) Male- Male Competition (intracompetition)
2) Female Choice (Introcompetition)
3) Fall under the umbrella of sexual selection
According to Darwin, Secondary Sexual Characteristics evolved due to …. Male - Male Competition (3)
1) Intra - On the inside (within)
2) Members of ones sex (usually males) compete with other members in a process called intrasexual competition
3) Secondary sexual characteristics give males fitness advantage via intra competition
According to Darwin, Secondary Sexual Characteristics evolved due to …. Male - Male Competition should lead to the appearance of..
1) Traits associated with winning battles
2) Traits for advertising a male’s competitive ability
3) Think about the GELADA’S LONG CANINES
What is so special about the Geladas (2)
1) Long canine
2) Eat grass and teeth are not for hunting!
According to Darwin, Secondary Sexual Characteristics evolved due to …. Female Choice ( intersexual Selection_
1) Darwin hypotheisized that some traits (women mainly) evolved not for survival but BECAUSE women preferred them
2) Make females more attracted to males (male secondary sexual characteristics)
Sexually Selected Traits due to Female Choice Examples (4)
1) Skin colouration
2) Ornaments
3) Behaviour / Acoustic courtship
4) Pelage (fur)
Sexually Selected Traits due to Female Choice Examples -Why might a female be attracted to these traits?
Wasting energy shows possession of energy
Sexually Selected Traits due to Female Choice Examples of wasting energy to show possession of energy
Indian Peafowl
Sexually Selected Traits due to Female Choice Examples of wasting energy to show possession of energy - Indian Peafowl (2)
1) Longtails require energy
2) Long tells shows you have expendable energy therefore expensive trait / sexy
Natural Selection & Sexual Selection - What’s the bottom line?
Biological fitness
Natural Selection & Sexual Selection - What’s the difference? ***** (4)
1) NS operates on survival, SS operates on fitness
2) NS emphasizes getting to adulthood and staying alive as long as possible
3) Once an adult - SS kicks in whereas NS kicks in since day one
4) SS operates more on men
5) SS is a social environment rather than the traditional environment of survival of the fitess
Who is Triver? (2)
- Applied the principles of sexual selection to male-female behaviour as well as morphology
- That parental investment is a key variable controlling Sexual Selection
What is Parental Investment?
Any investment by the parent in an individual offspring increases the offspring chances of survival ( and hence fitness) at the cost of the parent investing time in another offspring
Parental Investment (3)
1) Investment by the parent in an individual offspring
2) hence increases offspring fitness
3) Cost = investment to other offspring
- Limited investment budget
What are the three conflicts in parental investment? (3)
1) Successive offspring issue - limited budgets
2) Parents and new offspring balance
3) Different parental roles and cost
What are the three conflicts in parental investment? - Different parental roles and cost - What is the difference between males and female cost
Females have high-cost whereas males have low cost
What are the three conflicts in parental investment? - Different parental roles and cost - Name four parental investment cost to females (4)
1) (Anisogamy) Large nutrient eggs
2) A limited number of eggs
3) Gestation cost is high
4) Lactation (Lactational Amenorrhea)
What are the three conflicts in parental investment? - Different parental roles and cost - Name four parental investment cost to males (4)
1) Tiny sperm eggs
2) An infinite number of sperm eggs
3) No Gestation
4) No Lactation
What are the three conflicts in parental investment? - Different parental roles and cost - Name four parental investment costs to females - What is Anisogamy?
Sexual reproduction by the fusion of dissimilar gametes (conception) Female Gamete is BIG and contains cytoplasm organelles needed for reproduction. Very expensive
What are the three conflicts in parental investment? - Different parental roles and cost - Name four parental investment costs to females - What is Gestation?
The period where the mother is pregnant very high in time / energy
What are the three conflicts in parental investment? - Different parental roles and cost - Name four parental investment costs to females - What is Lactation?
Secretion of milk from mammary gland (titties) provides nutrients to the infant. VERY expensive
What are the three conflicts in parental investment? - Different parental roles and cost - Name four parental investment costs to females - What is Lactational Amenorrhea
Temporary fertility that occurs after a female gives birth when she is BREASTFEEDING (hormones)
What are the consequences of sex differences in parental investment? Females
Sexually mature females spend most of their times either pregnant or lactation period
do most females reach menopause?
No, menopause is when your period stops = not sexually viable
What are the consequences of sex differences in parental investment? Males 3
1) Very competitive and rare because
2) Sexual mature women spend most of their time either pregnant or in a state of lactational amenorrhea
3) Cost to reproduce is trivial for men
Sex and Optimal Strategies for each party - Trivers MAIN claim - Males strategy
Go for as many fertilization as possible and move on - little or nothing to lose energy-wise - Be a playa / dead beat
Sex and Optimal Strategies for each party - Trivers MAIN claim - Female strategy
Be very choosy
-Males must provide assistance, territory, good genes
Sex and Optimal Strategies for each party - Trivers MAIN claim - Female strategy - What must male provide (30
1) Assistance
2) Territory
3) Genes
Important point - it not about being __ & __ per say, but about the level of Pi this is what determines ____ & ____
Male & Female
Sex differences!
The more similar the level of parental investment between the sexes, the more similar the sexes will be in (2)
1) Behaviour
2) Morphology
The Different level of parental investment corresponds with many
behaviour and morphology
Three VERY important parental investment between male * females (3)
1) Potential Reproductive Output
2) Variation in reproductive success
3) Limiting factors
Three VERY important parental investment between male * females - Potential Reproductive Output - Total reproductive output for females primates is limited (3)
1) Have a reproductive lifespan
2) Their interbirth interval
- gestation
- Lactation
- Lactational Amenorrhea
3) Low reproductive potential relative to males
Three VERY important parental investment between male * females - Potential Reproductive Output - Total reproductive output for males primates is high (3)
1) Males reproductive output is correlated with their ability to find conceptive females
2) If he has high access to conceptive females - he can have high reproductive success
3) Males have higher reproductive success
Females have a higher reproductive output than males - t or f
FALSE
Three VERY important parental investment between male * females - Variance in reproductive success - Females
1) Females tend to have the same variance in the number of babies they have. Even in hierarchies structures. = Low variance
2) Females compete but not over males USUALLY
Three VERY important parental investment between male * females - Variance in reproductive success - Males (2)
1) Males high levels of reproductive variance. Some dudes ball while other flops
2) Higher competition for females
Three VERY important parental investment between male * females - Limiting factors - Females
Limited by access to energetic resources
Three VERY important parental investment between male * females - Limiting factors - Males
Limited by access to reproductive opportunities
Summary: Parental Investment - Men Vs women
Low vs high
Summary: Potential Reproductive Output - Men VS women
High vs low
Summary: Variance in reproductive success - Men VS women
HIgh vs low
Summary: actor Limiting reproductive success - Men VS women
Access to fertile females - Access to energetic food
