Week 9: Individuals: Metabolism, Life history, Ageing, Dispersal

Question 1

Define metabolic rate and understand how it is measured

Answer 1

The rate of energy consumption

Basal Metabolic Rate: organ function, cellular repair, body heat

Measure (Basal): O2 consumption (respirometer), CO2 output

Measure (Field): inject water labelled with uncommon isotopes

Question 2

Explain the relationship between body size and metabolic rate

Answer 2

Increases with size: heavier, more energy for basic functions, more air/ water resistance

Mass specific metabolic rate = decreases with size: SA: volume limits metabolism in big animals

Question 3

Differentiate between endothermy and ectothermy, and give examples of each

Answer 3

Endothermy (warm blooded): internal body temp regulation, hibernation, adaptive heterothermy (e.g. camels can’t sweat)

Ectothermy (cold-blooded): rely on external env for temp regulation, e.g. sun basking lizards

Question 4

Describe how metabolic rate and thermoregulation strategies relate to an organism’s life history

Answer 4

Selection determines life history (reproduction + lifespan) which determines metabolism.

Question 5

Advantages and limitations of ecto vs endo

Answer 5

ENDO:
+ active when cold/night,
- cost of high metabolism, high food and insulation need
ECTO:
+ no metabolic cost of temp reg, more E for growth in warmer temps
- no optimal temp so slow growth, movement, digest

Question 6

Variation in life histories

Answer 6

Life history: age specific schedule of reproduction and mortality of a population of individuals
-size: small= high met = faster maturation + reproduction = young death
VS large = opposite
- distantly related organisms can be similar
-speed of ageing/ maturation/ gestation

Question 7

Key trade-offs that shape life history strategies

Answer 7

-between energy put towards reproduction, survival and reproduction
-offspring size/ quality vs number
-However variation in RESOURCES can obfuscate trade-offs

Question 8

Lack’s optimal clutch size theory

Answer 8

largest number of young for which the parents can, on average, provide enough food
-selection wants to favour the max amount of offspring surviving to reproduce

Question 9

Semelparity (one-off reproduction) and iteroparity (multiple)

Answer 9

Semelparity: cost of reproduction is so costly, death is immediate, favoured when juvenile survival is much higher than adult
Iteroparity: breeds multiple time either seasonal or continuous, favoured when low juvenile survival compared to high adult survival

Question 10

Selection on reproductive timing

Answer 10

favours EARLY repro:
- more likely to survive to reproduce
-shorter generation time so higher fitness in growing populations

Question 11

Precocial and altricial species

Answer 11

Precocial: (born advanced), no need for parental care, BUT long gestation, less post-birth brain development, needs lots of resources to produce mature egg
Altricial (born helpless): lower resource investments in egg, larger potential brain, BUT parental cost is high

Question 12

Unique aspects of long-lived mammals, including the menopause (theories)

Answer 12

• Extended care: allow offspring to develop large brains, learn skills and sociality
• Menopause (female lifespan longer than reproductive period)
  ? Mother Hypothesis: increasing risk of death through childbirth with age
  ?Grandmother: help raise grandchildren rather than risk death by having more
  ?Reproductive conflict: avoids conflicts with daughters for offspring

Question 13

Ageing definition

Answer 13

a decline in biological function over time leading to death
increasing mortality and decreasing reproductivity

Question 14

Extrinsic and intrinsic drivers of ageing

Answer 14

Ex: hazards can cause death without ageing (e.g. Predation, disease) some factors such as environmental pollutants, diet and temp can accelerate ageing
In: can accelerate/slow ageing genes that determine patterns of body maintenance

Question 15

The diversity of ageing patterns across taxa

Answer 15

Humans (most mammals): Mortality low till 80s then suddenly spikes, reproduction peaks early then nothing
-unitary organisms = classic ageing VS modular = often very slow

Question 16

The main evolutionary theories of ageing

Answer 16

• Mutation Accumulation (Medawar): force of selection declines with age so late acting deleterious mutations accumulate in populations
• Antagonistic Pleiotropy (Williams): genes that are beneficial in early life but harmful in late, selection doesn’t remove as initially beneficial
  Disposable Soma: based on trade-offs, the body is disposable without the ability to reproduce

Question 17

Hyperfunction theory of ageing

Answer 17

-not to do with declining function, rather excess of growth
-evidence: inflammation, hypertension, cancer
-potential to reduce growth pathways to reduce ageing

Question 18

Peto’s Paradox: cancer rates across animals of different sizes

Answer 18

T: Big animals should have more cancer because of increased cell divisions
VS
R: contain cancer suppressor mechanisms

Question 19

Evolutionary conserved genetic regulators of ageing

Question 20

The potential for anti-ageing interventions in humans

Answer 20

+ anti-disease, tumour suppressor
- reduce fertility

Question 21

Dietary restriction

Answer 21

Reduction in food intake avoids overconsumption of toxic nutrients as well as reallocation of resources to survival from reproduction = slower ageing

Question 22

Define Dispersal and Migration and differentiate between these

Answer 22

• Dispersal: Movement away from the place of birth
  Natal: at point of birth
  Adult: On reaching sexual maturity
• Migration: regular pattern of movement between two places with INTENT to return

Question 23

Given an example, state if dispersal is active or passive and relate diversity of means of dispersal.

Answer 23

Actively: under own power study by marking, proximity, detectors, GPS trackers. E costly, requires adaptation
Passively: moved by environment or other animals and studied by genetic markers and genotype trees. E cheap and provides lower assurance of suitable destination

Question 24

Relate the main theories as to why organisms disperse.

Answer 24

Costs:
- E: active directly uses energy, passive in terms of resources
- Risk: active means increased predation in unfamiliar territory, lack of group protection
Benefits:
- don’t compete with parents/siblings
-escape extinction in temporary habitats
- reduces inbreeding

Question 25

When given an example mammal biology, predict if it will show male or female biased dispersal.

Answer 25

-male: if sisters remain -female: if dominant male is father when sexually mature

Question 26

From exampled providing mean and variance in dispersal distance, state which species will colonise a landscape most quickly.

Answer 26

movement depends on furthest dispersing individuals: advance then back fill Variance means more than mean

Question 27

Relate the ecological forces favouring migration, and the sensory systems and cues used by migrating animals.

Answer 27

Diurnal- depth for zooplankton. avoid low O2 region and damaging impact of high light Seasonal: winter/summer habitats in animals. high productivity in summer or driven by wet seasons HOW: -migration corridors - Telling the time by length of days/ circadian clock - Navigation: following landmarks, coasts, sunset, polarisation of lights, stars, magnetic compass

Question 28

Outline costs and benefits of group living.

Answer 28

+ reduction in predation (dilution, vigilance, confusion, group defence), improved predation success (hunting in groups, information exchange), co-operative activities. - Attraction of predators (may attract more predators by smell/sounds easier), increased parasite/pathogen burden (increased transmission), competition of resources (share food source)

Question 29

Outline the consequences of group living for mammalian mating systems; social evolution and cognitive evolution

Answer 29

- Monogamy: solidarity. -Unimale Polygyny: one male and small group of females -Multimale Polygyny: large groups of males and females -social brain: group living means need to track individuals, memory and network -Cognitive Consequences: need to track relationships with others