Physiology 1: Adaptation, acclimation and plasticity

Question 1

What is an adaptation?

Answer 1

Any trait that increases the fitness of an organism in its environ = result of natural selection

Question 2

Describe the features of an adaptation (e.g how they occur, time scale etc.)

Answer 2

• Organism that has this trait survives better and leaves more offspring in the next gen
• Trait is selected for
• Genetically determined, heritable
• Evolutionary time scales (very long)
• Behavioural adaptations → E.g bears hibernating over winter

Question 3

What is acclimation?

Answer 3

Physiological compensatory response to environ change

Question 4

Describe the features of an acclimation

Answer 4

• Short-term response
• Not heritable
• May be immediate, or build up over time
• Mostly experimental/ artificial

Question 5

What is plasticity?

Answer 5

Ability of living organisms to change their ‘state’ in response to any stimuli

Question 6

Describe the features of plasticity + examples

Answer 6

Occurs at any level of complexity: molecular, cellular, systemic and behavioural
Limited (can be adaptive and evolve)
E.g rockhopper penguins live in a variety of climates (subtropics to subartics)
E.g homeostasis in humans

Question 7

What is acclimatisation?

Answer 7

Physiological compensatory response to environmental change

Question 8

Describe the features of acclimatisation + example

Answer 8

Short term response to environ
Not heritable
May be immediate, or build up over time
Natural/ slightly longer
E.g adjustment of sheep to hotter temps by shedding wool

Question 9

At high altitudes there’s low atmospheric O2, what does this mean for pO2 and Hb affinity?

Answer 9

High altitude: low atmospheric oxygen
High pO2, Hb high affinity, O2 binds readily

Question 10

At low altitudes there’s low atmospheric O2, what does this mean for pO2 and Hb affinity?

Answer 10

Low altitude: Low pO2, Hb low affinity, O2 released

Question 11

In the altitude case study, what were the results of measuring physiological stress (Hb) in both pop.s?

Answer 11

Andean pop. higher Hb conc than their lowland ancestors
Tibetan pop. no sig diff between ancestors
= diff in response to living at high altitudes

Question 12

In the altitude case study, what were the results of measuring physiological stress (O2 saturation) in both pop.s?

Answer 12

Andean pop. lower O2 saturation than lowland ancestors
Tibetan pop. lower than Andeans
= suggests Andeans less stressed by hypoxia

Question 13

What is the trade off of having higher Hb levels to deal with high alitiudes?

Answer 13

Higher Hb → more viscous blood → strains heart → whilst increased hB deals with hypoxia = trade off

Question 14

What is adaptive plasticity?

Answer 14

Genetically controlled diff that confers an adaptive change in the extent or direction of a plastic response

Question 15

What is heritability?

Answer 15

Proportion of total phenotypic variance attributable to genetic relationships among individuals

Question 16

What do the results of the altitude case study suggest?

Answer 16

• Population genetic diffs
• Higher O2 saturation allele might be favoured by natural selection

Question 17

How does the presence of the O2 saturation gene in Tibetan pop. influence fitness?

Answer 17

No association between presence of O2 saturation gene and the number of pregnancies / live births
Homozygous recessive mothers = lower no. of surviving children compared with the O2 saturation gene
Increased infant mortality rates in homozygous recessive mothers
= Life stage that the O2 gene is acting upon is the infant / child stage