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Chapter 1
Animal Physiology
Physiology helps us understand:-The fundamental biology of all animals-Human health and disease-The health and disease of nonhuman animals of importance in human affairs
Figure 1.1 Pacific salmon
migrating upriver to their
spawning grounds
Figure 1.2 The study of
physiology integrates
knowledge at all levels of
organization
Figure 1.2 The study of
physiology integrates
knowledge at all levels of
organization (Part 1)
Figure 1.2 The study of
physiology integrates
knowledge at all levels of
organization (Part 3)
Physiology’s Two Central Questions About How Animals Work
What is the mechanism by which a function is accomplished?
Origin: How did that mechanism come to be?
The mechanism of light production
by fireflies (Photinus)
Figure 1.3 The mechanism of
light production by fireflies
(Photinus) (Part 2)
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
Terms to Know
Male fireflies employ their
mechanism of light production for an
adaptive function: mate
attraction
Structures that are similar in gross appearance,
functional performance, and adaptive significance can differ dramatically in details of how they are assembled and work
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 traitsThe ways in which diverse phylogenetic groups of animals
both resemble each other and differThe ways in which physiology and ecology interact, in the
present and during evolutionary timeThe importance of all levels of organization – from genes to
proteins, and tissues to organs-for the full understanding of physiological systems
Topics this Semester
AnimalsEnvironmentsEvolutionary Processes
Three Major Topics
1. Structurally dynamic2. Organized systems that
require energy to maintain organization
3. Both time and body size are fundamental significance in the lives of all animals
Animals
The atoms of their bodies are in dynamic exchange with the atoms in their environments (isotope
studies)
Structurally Dynamic
Although the particular atoms change the overall structure stays the same-
energy required
Animal Organization
Figure 1.6 Conformity and
regulation
Figure 1.7 Mixed
conformity and regulation in a
single species
Regulation demands more energy than conformity because regulation represents a
form of organization
Homeostatsis – the existence of regulatory systems that automatically make
adjustments to maintain internal constancy
Example: negative feedback – controlled variable brought back to its set point
Changes in response to the external environment:1. Acute Changes – short term, reversible, in individuals2. Chronic Changes – long term, reversible, in individuals3. 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
senescence5. Changes controlled by periodic biological clocks-changes that occur in
repeating patterns
Five Time Frames in Which Physiology Changes
Figure 1.8 Heat acclimation in
humans as measured by
exercise endurance
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
Phenotypic Plasticity – the ability of an animal to express two or more genetically controlled phenotypes,
can evolve
Developmental changes – programmed changes from conception to senescence
Changes controlled by periodic biological clocks-changes that occur in repeating patterns
Changes in response to the internal environment
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
Changes in response to the internal environment
Figure 1.9 Length of
gestation scales as a regular
function of body size in
mammals
Are Mountain Reedbuck and Bushbucks Specialized or Ordinary?
1. Animals2. Environments3. Evolutionary Processes
Three Major Topics
1. Temperature2. Oxygen3. Water
Environments
A measure of intensity of the random motions that the atoms and molecules in the material undergo (high temps=lots of movement)
Temperature
Conformers: Fish in the sea around Antarctica spend their entire lives at body temperatures near –1.9°C
Figure 1.11 Butterfly
biogeography
Decline in Diversity Towards the Poles
Figure 1.12 A thermophilic
(“heat-loving”) lizard common
in North American deserts
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.
Oxygen
Figure 1.13 Performance in
an O2-poor environment
High elevations have less oxygen in them due to air pressure being low
Density layering can cut off the O2 supply to the deep waters of a lake
Universal solvent in biological systemsRequired 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
Water
Figure 1.16 Microenvironme
nts in the Arizona desert near Tucson
The Environment an Animal Occupies is Often a
Microenvironment or Microclimate
Microenvironments in the Arizona desert near Tucson
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
Figure 1.17 Microenvironme
nts in deep snow in the far
north
1. Animals2. Environments3. Evolutionary Processes
Three Major Topics
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.
Evolution
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
Terms to Know
Processes in which chance assumes a preeminent role in altering gene frequencies.
-Random deaths-Founder effects
Genetic Drift
The control of an allele of a single gene of two or more distinct and seemingly unrelated traits- can lead to nonadaptive outcomes
Pleiotropy
Direct observation
The comparative method – how a function is carried out by related and unrelated species
Studying Adaptation
Figure 1.18 The comparative
method
Study lab populations over many generations – fruit flies
Single-generation studies of individual variation
Studying Adaptation Cont.
Figure 1.19 Physiological
variation among individuals of a
species
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
Studying Adaptation
There must be genetic diversity of a trait for it to evolve
Evolutionary Potential
Figure 1.20 The effects of
genetic diversity on evolutionary
potential