Animal Physiology chapter 1

What is the mechanism by which a function is
accomplished?
Origin: How did that mechanism come to be?

 Natural Selection: the increase in frequency of genes that produce phenotypes that
raise the likelihood that animals will survive and reproduce
 Adaptation: a physiological mechanism or other trait that is a product of evolution
by natural selection
 Adaptive Significance: Why the trait is an asset – why natural selection favored the
evolution of a trait

Mechanisms and adaptive significance are distinct concepts that do not imply each
other

The mechanisms by which animals perform their life
sustaining functions.
The evolution and adaptive significance of physiological
traits
The ways in which diverse phylogenetic groups of animals
both resemble each other and differ
The ways in which physiology and ecology interact, in the
present and during evolutionary time
The importance of all levels of organization – from genes to
proteins, and tissues to organs-for the full understanding of
physiological systems

Animals
Environments
Evolutionary Processes

1. Structurally dynamic
2. Organized systems that
require energy to maintain
organization
3. Both time and body size are
fundamental significance in
the lives of all animals

The atoms of their bodies
are in dynamic exchange
with the atoms in their
environments (isotope
studies)

Although the particular
atoms change the overall
structure stays the same-
energy required

Changes in response to the external environment:
1. Acute Changes – short term, reversible, in individuals
2. Chronic Changes – long term, reversible, in individuals
3. Evolutionary Changes – alteration of gene frequencies (genotypes) over
the course of multiple generations in population exposed to new
environments
Changes in response to the internal environment:
4. Developmental changes – programmed changes from conception to
senescence
5. Changes controlled by periodic biological clocks-changes that occur in
repeating patterns

Acclimation – chronic response to a laboratory
environment – controlled environment with just a few
changes
Acclimatization – chronic response to a natural
environment (winter/summer, high/low elevation)
Norm of Reaction – Correspondences between
phenotypes and environments (high melanin & high sun),
can be adaptations

Developmental changes – programmed changes
from conception to senescence
Changes controlled by periodic biological clocks-
changes that occur in repeating patterns

Body Size – Many traits vary in regular ways with
their body size among related species – brain size,
heart rate, energy use etc. Scaling – the study of
these relationships

Are Mountain Reedbuck and Bushbucks Specialized or Ordinary?

1. Animals
2. Environments
3. Evolutionary Processes

1. Temperature
2. Oxygen
3. Water

A measure of intensity of the random
motions that the atoms and molecules in
the material undergo (high temps=lots of
movement)

Decline in Diversity Towards the Poles

Need for oxygen due to need for
metabolic energy.
Releasing energy from organic
compounds (food) release hydrogen.
This is combined with oxygen to form
water.
The suitability of an environment
depends on availability of O2.

 High elevations
have less
oxygen in them
due to air
pressure being
low

Universal solvent in biological systems
Required for blood and all other body
fluids to have their proper compositions
Water bound to proteins and other
macromolecules as water of hydration
required for proper chemical and
functional properties

At head height air temps approach
50°C in summer and 7°C in winter
In the burrow
of a kangaroo
rat at 1 m
beneath the
soil surface,
temperatures
remain
between 15°C
and 32°C

A change in gene frequencies over time
in a population of organisms
Not necessarily due to adaptation which
occurs due to natural selection
Nonadaptive evolution occurs when
gene frequencies change but does not
confer a survival or reproductive
advantage.

Processes in which chance assumes a
preeminent role in altering gene
frequencies.
-Random deaths
-Founder effects

The control of an allele of a single gene of
two or more distinct and seemingly
unrelated traits- can lead to nonadaptive
outcomes

Direct observation
The comparative method – how a function is carried
out by related and unrelated species

Study lab populations over many generations – fruit
flies
Single-generation studies of individual variation

Creation of variation for study – knock out animals,
RNA interference, allometric engineering
Studies of the genetic structures of natural
populations - clines
Phylogenetic reconstruction-making family trees
from molecular data

There must be genetic diversity of
a trait for it to evolve

Animal Physiology chapter 1

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Animal Physiology chapter 1

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