Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

3s1: Evolution of health and disease > Week 2 > Flashcards

Week 2 Flashcards

1
Q

What things are investigated in life history traits?

A

Size at birth, growth rate, age and size at sexual maturity, number offspring, size and sex ratio, age- and size-specific reproductive investment and mortality schedule, lifespan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is R0?

A

Lifetime expectation of female offspring; net reproductive rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you calculate R0?

A

sum of lxmx
lx = survival to age x
mx = birth rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does life history maximise?

A

maximises r, intrinsic rate of increase, or Malthusian parameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does Euler-Lotka equation calculate?

A

r (fitness) related to history parameters (survival probability and fertility)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is an example of an event history diagram showing how lifespan and fecindity are related?

A

Wildtype - 0.75 dead by day 18 but producing 100 + eggs for 3 days
Daf-2 - 0.25 dead by day 18 but only 1 day are 100+ eggs produced
Trade off both produce same amount of eggs but wt are earlier but dont live as long

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why do trade offs occur in nature?

A

Constraints prevent life history variables leading to high r from being simultaneously maximised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are hypothetical examples of trade offs?

A

Traits that increase r might make the organism more vulnerable to ecological hazards (predation, parasitism)

May be constraints that put limits on what can be achieved (reproduction vs lifespan)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What important trade offs in nature?

A

Current reproduction and survival
Current and future reproduction
Number, size and sex of offspring
Reproduction and immune status

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a trade off between nursing and mortality rate?

A

Nursing roe deer have increased mortality rate per year, increasing with age
Non nursing mothers dont have an increase in mortality rate except at 14 years old

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an example of human familes and the data used for life to child impact?

A

Finland lutherans n = 22,000 people
Strict Lutherans - Required to submit accurate censuses,
1700s-1900; low paternity outside marriage
2200 families average family size ~6; 60% surviving to adulthood, ~80-90% followed until death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What was the link between maternal longevity with child in the Lutherans Fins?

A

Mothers life expectancy decreases with more sons
Negligable change in life expectancy with more daughters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How are physiological trade offs measured?

A

Phenotypic manipulations
Genetic manipulations
Phenotypic correlations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an example of phenotypic manipulations?

A

Manipulations that extend lifespan also reduce reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is an example phenotypic manipulation in primates?

A

Macaques > 27 years old (old)
Calorie restricted diet - CR is adequate nutrition on 30 percent fewer calories

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What was the outcome of calorie resticted diet in Macaques?

A

CR diet - lower levels of cancer, diabetes, heart disease, brain atrophy and lean-muscle loss

5/38 CR monkeys died from age-related causes 14/38 controls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is an example of genetic manipulations for measuring trade offs?

A

Genetic manipulation of reproductive pathways (e.g. removal of germ line & nutrient sensing) leading to extended lifespan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What was an experiment genetic manipulation for measuring impacts of lifespan?

A

Drosophilia melanogaster - remived germ line cells
Both male and female flies that have germ line cells removed lived longer than wildtype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is an example of phenotypic correlations for measuring trade offs?

A

Measurements on un-manipulated individuals e.g negative associations between offspring and lifespan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is an example of phenotypic correlations for impact on lifespan?

A

The Lutharan finnish women (more sons lower maternal longevity, dughter had a minor impact)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the problems with phenotypic correlations?

A

This approach cannot directly demonstrate causality
Most / all work on humans is correlational

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How can you measure evolutionary trade offs?

A

Direct and correlated responses to artificial selection

23
Q

How did they place an artificial selection on Drosophila lifespans?

A

Select flies that bred either young or old across 6 generations

24
Q

What where the results for the artifical selection on drosophila?

A

Direct response: short and long lived flies
Correlated response long lived females produced fewer progeny (potentially shows trade off between lifespan and fertility)

25
Why are trade offs important?
human health suggests that we ‘can’t have it all’ many constraints on what can be achieved
26
What determines the timing of reproductive maturity?
Balance between mortality risk against fertility
27
What determines survival to reproductive age?
Risk (‘danger’, disease, stress) Nutrition
28
What is a summery of fertility as a function of size?
Growth / nutrition
29
What is a prediction if survival to maturity is low?
Early sexual maturation is favoured by natural selection
30
What is a prediction when subsequent annual survivial is low?
‘One shot’ reproduction favoured by natural selection
31
What are prediciotn of fertility related to growth/food?
Earlier sexual maturation when food abundant Later sexual maturation when food limiting
32
Why is expected age at reproduction plastic?
Depending on mortality risk versus fertility (food / growth)
33
What experimental evidence for plasticity in timing of reproductive maturity?
Group of daphnia put in tank which had contained a fish predator (fish treatment) and then measured the reproductive response
34
What were the results for the daphnia in fish treatment tank vs control?
Treatment group: Reached sexual maturity earlier Were smaller at sexual maturity Had larger broods at earlier age This showed that they can read conditions and adjust growth and reproductive accordingly
35
What is evidence of reproductive maturity in humans?
22 groups of non-industrialised humans: Age at menarche positively related to survival and life expectancy to age 15 Age at first female reproduction positively related to survival to age 15 All show negative relationship with body size
36
What is the relationship between body size and survivorship?
Sexual maturity related to body size and survivorship – but opposing forces Balance of these two opposing forces determines optimum age at first reproduction
37
What is an example if age of sexual maturity modelled?
Modeled optimal age at sexual maturity in Ache hunter-gatherers Used mortality data, growth rate and body size
38
What is the relationship between body size and fertility for ache hunter gatherers?
Females - positive relationship between fertility and weight Males - positve relationship between fertility and weight until 65kg where it then decreases
39
What is the probability of death with age for ache hunter gatherers?
Both start high, quickily drop stabilising ay a low level before increasing with age. Males slightly higher than females particually arounf middle to early old age
40
What is Hill and Hurtado's model of optimal age of sexual maturity?
Optimal age at maturity at bottom axis With survival to maturity and potential fertility at maturity (due to body size) overlayed Optimum = bold solid line (where the 2 lower lines cross)
41
What happens to Hill and Hurtado's model when survival is lower?
If survival is lower (you drop the la line lower), then the lines cross earlier, meaning optimal age at maturity will be lower and vice versa
42
How well does Hill and Hurtado's model work?
Pretty well. Model 1 was 1.5 years off, model 2 was better (models 1 and 2 adopt different ways of calculating expected fertility as a function of age and weight)
43
In what other case studies did Hill and Hurtado model work?
spot on for !kung hunter-gatherers Successfully predicts earlier menarche for white women from the US (controversal use for prediciting women in USA)
44
Why have animals evolved reactionairy reproduction?
Enables expression of optimal age at sexual maturity according to specific aspects of environment, e.g. mortality risk
45
What evidence is there for perceived mortality risk associated with age at first reproduction?
Wilson & Daly 1997 - US neighbourhoods with the lowest life-expectancy have the highest teenage pregnancy rates. Suggests: Women who perceive themselves to be in a risky environment may reproduce earlier
46
What is the link between reproduction and risk?
Optimal age at reproduction can be predicted - From size / fertility and mortality risk data Risk, perceived or actual varies between individuals and groups - Associated with age at sexual maturity
47
What are the found levels of testosterone?
Found at higher levels than ‘required’ for spermatogenesis and sexual functioning
48
What are the trade offs with elevated testosterone?
Immunosuppressive Behaviour - higher ‘future discounting’ Higher risk of prostate and testicular cancer Males more costly or ‘difficult’ to produce? Higher mortality; female > male lifespan
49
Why do males express higher levels of testosterone?
Males that ‘display’ high testosterone show they can thrive despite its costs Cannot be ‘faked’ by lower quality individuals
50
What are the predicitions if the handicap hypothesis is correct?
Males who display high testosterone should: be more attractive to females? have higher mating success? possess other traits that signal high quality?
51
How is testosterone displayed?
At sexual maturity: The chin becomes longer The vertical ramus becomes flared Eye socket height decreases, brow ridges develop
52
Is there a preference for masculine/ high testosterone faces?
No clear preference for facial testosterone, from several studies Except, perhaps, when associated with specific sexual strategy (SOI) score
53
Why is there no clear preference for facil testosterone?
Sometimes preferences associated with phase of the menstrual cycle Women in modern societies have different hormonal profiles across the menstrual cycle cf women in anthropological studies, or in our evolutionary past
54
What is the testosterone and male quality?
Phenotypic correlation Men with higher facial testosterone report fewer illnesses

3s1: Evolution of health and disease (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions