Summary
Summary Adaptation Physiology of Animals (NWI-BM010C)
- Course
- Institution
Extensive summary of all lectures of adaptation physiology of animals (NWI-BM010C).
[Show more]
Seller
Follow
roos1397
Reviews received
Content preview
Adaptation Physiology of AnimalsHomeostasis and allostasis
Adaptation → should be genetic and inheritable to the next generation
Animal Adaptation Physiology
- Adaptation → a heritable physical or behavioral trait that serves a specific purpose function
and improves an organism’s fitness or survival
Time frames in which physiology changes
Physiological responses to the environment
- Adaptation sensu stricto usually takes a long time, occurs over generations, and is non-
reversible
o Adaptation: evolutionarily, genomically-fixed responses
- Acclimatization (‘fast’, i.e. within the life span of an organism)
- Acclimation: the response to experimental conditions; it tells us about the capacity of an
organism to handle disturbances, within the bandwidth of the genotype and thus its
evolutionary capacity (and success)
- Example: a camel is adapted to desert life, a human being can acclimatize to desert
conditions, or we can force a mouse model to acclimate to desert conditions (called
acclimation)
Evolutionary concepts are related to processes or patterns
- Process, natural selection, which drives adaptation
- Pattern, e.g. the homology of the human arm and a bird wing, structures with similar
underlying bones, modified in shape but not in basic layout
o The tails of say a fish and a dolphin are analogous structures
- Adaptation
o A dolphin is wonderfully adapted to move in water (is adapted to an environmental
factor)
o Biston betularia, melanism in a moth providing camouflage in soot-blackened birch
trees (adaptation in the making)
, o Darwin finches on Galapagos islands: lineages branching out from a common
ancestor, due to different environmental conditions prevailing in the different
geographic locations (adaptation, adaptive radiation); beak form adapted to
available food resources
Adaptation
- Consider the degree of environment-specificity of adaptations
o The nature of selection favoring and adaptation may change over time (exaptation)
o New features that evolve must integrate well with the rest of the bodily structure
and organization (co-adaptation)
- Examples
o The origin of jaws is not environmental-specific, they are very useful under a wide
range of environmental conditions and never got lost. Jaws arose from the skeletal
supports of the first pair of gill supports; gills were enlarged for improved breathing
and then underwent changes for improved eating (an exaptation)
o The cranium and vertebral column are a design improvement in all environments,
never lost in vertebrates; walking legs (tetrapods) and wings (birds) are more
environment-specific. The latter have been lost or reversed (cataceans and penguins,
respectively)
Evolution and adaptation – Darwinism in a nutshell
- Natural selection (for adaptations) is the driving force for evolution
- At least some of the differences between individuals, which impact
their survival and fertility, are inheritable
- During the ‘struggle for resources’, the fittest individuals will survive
(i.e. the frequency of the beneficial gene in the population
increased) and reproduce
Evolution and homeostasis
- Homeostasis and allostasis are the mechanisms/processes required to adapt to a dynamically
changing environment
Concept of homeostasis
- Claude Bernard developed the physiological concept of homeostasis, a fundamental concept
in modern physiology/biology; he noted constancy of chemical composition and physical
properties of body fluids, despite changes in the environment
- He claimed that this ‘fixity of the milieu intérieur’ (mainly blood in his case) compared to the
milieu exterieur was essential to the life of higher organisms
Homeostasis
- A relatively stable state of equilibrium or a tendency toward such a state between the
different but interdependent elements or groups of elements of an organism, population, or
group
- In other words: homeostasis is the property of an open system, especially living organisms
(or parts/organs thereof), to regulate its internal environment so as to maintain a stable
condition, by means of multiple dynamic equilibrium adjustments controlled by interrelated
regulation mechanisms
,Homeostatic control mechanisms
- Key words: stimulus → receptor (sensor) → control center → effector
Examples of homeostasis in the animal body: states of balance in the body
Negative feedback
Positive feedback
- Oxytocin (only known hormone that provides positive feedback)
, Homeostasis
- Homeostasis has survival (i.e. adaptive) value because it means an animal can adapt to a
changing environment, by becoming (partly) independent
- E.g., you can deal with the temperature difference you face when you step out the front door
- The body will attempt to maintain a norm, the desired level of a factor to achieve
homeostasis (setpoint)
- However, it can only work withing tolerable limits; extreme conditions will disable the
negative feedback mechanism, and pathologies may develop
Homeodynamics
- A more recent term that ‘updates’ homeostasis, defined in a dictionary as:
o ‘the pysiologycial process by which the internal systems of the body (e.g. blood
pressure, body temperature, acid-base balance) are actively maintained at
equilibrium, despite variations in the external conditions’
- Homeodynamics attempts to add emphasis to the dynamic, active, ever-adjusting
physiological nature of these processes
There was growing awareness that strict homeostatic control is not always the explanation for
physiological processes: an example…
- Arterial blood pressure (continuous registration) fluctuates to meet predicted demand
o No defense of a setpoint
o Rather responsiveness to rising and falling demand
o
- Arterial pressure fluctuates, even in a subject with established hypertension
o No defense of a fixed setpoint
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller roos1397. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.56. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
80364 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now