Evolutionary Biology 8

Question 1

What does an animals life history include

Answer 1

1) age and size of maturing
2) number and size of offspring
3) energy allocation to reproduction
4) timing of growth
5) dispersal patterns
6) number of reproductive events
7) lifespan and ageing

• varies in individuals and species

Question 2

what is lifetime reproductive success

Answer 2

an individual’s production of offspring during its lifetime

• selection = maximisation of LRS

Question 3

what is involved in lifetime reproductive success

Answer 3

• fast development
• rapid maturity
• high parental investment
• high reproductive rate
• long life
• reproduction is costly, species have to trade-off these factors to reach their maximum LRS (example compare elephants to mice)

Question 4

what intrinsic factors affect a species strategy of trade-off of life-history traits

Answer 4

Intrinsic

• energy/resource constraints
• genetic constraints
• phylogenetic constaints
• mechanical constraints
• physiological constraints

Question 5

what extrinsic factors affect a species strategy of trade-off of life-history traits

Answer 5

Extrinsic

• ecological factors (predation)
• climate constraints
• note all traits are under a continuum with all states being possible

Question 6

senescence

Answer 6

age-related deterioration of an organism leading to a decline in reproduction and probability of survival

Question 7

What are the 3 main theories for why we age ?

Answer 7

1) Mutation accumalation
2) antagonistic pleiotropy
3) disposable soma

Question 8

Mutation accumalation

Answer 8

Mutation that are deleterious later in life are more likely to be maintained in the population

• selection acts more strongly against genes that act negatively during reproducing age

E.g. huntingtons diesease , cause by a dominant allele expressed at 30-40 yrs of age (individual already reproduced )

Question 9

Antagonistic pleiotropy

Answer 9

Where 1 gene effects more than one phenotypic trait, good be good for one/now and bad for another/later.

E.g. Gene that causes overproduction of sex hormones - good during reproductive stage but can cause cancer later on.

Question 10

Disposable soma

Answer 10

Resources are finite – energy put towards one function (growth,
maintenance, reproduction) is unavailable for others. - trade offs

• limit towards maintenance causes somatic dmg
• high allocation towards reproduction = less energy for maintenance and growth

Question 11

Which theory of “why we age” is correct

Answer 11

it is likely all of them working together

Question 12

how does predation affect “when to mature” for species, give an example

Answer 12

E.g. guppys

in a population when all guppy’s are predated on the time of maturation is different to a population in which only baby guppy’s are predated on.

Question 13

what happens when just baby guppy’s are being predated

Answer 13

• Female maturation at smaller size
• more smaller offspring
• male maturation at a smaller size (weaker effect than in females)

Question 14

what happens when all guppys are being predated ,

Answer 14

• Female maturation at larger size
• fewer, larger offspring
• male maturation at a larger size (weaker effect than in females)

Question 15

Intrinsic factors affecting how many baby’s a species will have

Answer 15

• trade off between number and size of offspring
• offspring: better chance of surviving if larger
• Parents : smaller (but more) offspring are better

parent-offspring conflict

Question 16

Extrinsic factors affecting how many baby’s a species will have

Answer 16

e.g. songbirds - tropical and temperate bird species have diverse life histories

Tropical -> smaller clutches, fewer chicks, slower growth

Temperate -> larger clutches, more chicks , faster growth rate

*pattern against what you would expect (tropical environment more rich)

Question 17

How does the growth rate differ between tropical and temperate clutches of birds

Answer 17

• tropical slower but catch up by time of fledgling
• tropical nestings have higher growth rate for wings
• higher wing growth an advantage against high predation in tropics
• in tropics parent need to visit nest less (to keep safe) so tropical birds have smaller clutches to allow enough provision for increased wing growth.