What is Comparative Animal Central Themes of Comparative ...€¦ · actually or potentially...
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PSLY 4210/5210 Comparative Animal Physiology Spring 2010 What is ‘Comparative Animal Physiology’? Topic 1 – 1 What is “Comparative Animal Physiology”? Comparing physiologies of animals: “What does it mean?” Comparing physiological mechanisms? Comparing physiologically adaptive strategies? Comparative molecular biology? Much the same as for biology in general: Relationship between animal form and function Relationship between maintenance of complexity and homeostasis Acquiring and using energy Environmental constraints Evolution and adaptation Biodiversity and uniformity Central Themes of Comparative Animal Physiology Insights into the Relationships Between Organisms and Their Environment: Animals are adapted to their environments through past evolution. The organism is a compromise. The result of natural selection is adequacy (“Just good enough”), not perfection. Energy availability and utilization are important constraints on animal function. Body temperature regulation is expensive in time and energy. Its alternative (temperature conformity), results in variability in all physiological processes. Body size affects nearly every biological variable. Behavior is an important component of functional adjustment to the environment. Environmental cues help determine behaviors. Hierarchical Organization of Life Biomolecules and macromolecules Cells and subcellular components (e.g., organelles, membranes, and cytoplasmic elements) Cells/Organisms – individual ‘living things’ Populations –freely-interbreeding organisms inhabiting the same place at the same time Species – all organisms that can actually or potentially interbreed and produce fertile offspring Communities – collections of populations of different species inhabiting the same place at the same time Ecosystems – living organisms (communities) and their non-living environments Biosphere – all of Earth’s ecosystems: every part of Earth where life exists Most commonly studied by physiologists These two individuals share more than 98% of their genomes (perhaps less than 500 of their genes differ) Emergent Properties of Life Organisms are living systems . Systems are organized collections of parts. When energy is applied to systems, then new emergent properties appear that are more complex than the system’s collective properties (“the whole is greater than the sum of its parts”) Cells: perform synthesis of large molecules and chromosomal replication Populations: exhibit age structure, genetic diversity, natural selection Species: have reproductive isolating mechanisms (behaviors, chromosomal or germ cell incompatibilities) Communities: have coevolutionary relationships between species (e.g., competition, predation), and undergo predictable changes with time (succession) Ecosystems: recycle nutrients between living organisms and the non- living environment Biosphere: living things affect, and are affected by, the Earth’s biogeochemistry and climatic conditions Figure 1.1 The study of physiology integrates knowledge at all levels of organization
Transcript of What is Comparative Animal Central Themes of Comparative ...€¦ · actually or potentially...
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PSLY 4210/5210 !Comparative Animal Physiology !Spring 2010!What is ‘Comparative Animal Physiology’?!
Topic 1 – 1!
What is “Comparative Animal Physiology”?!
!Comparing physiologies of animals: “What does it mean?”!
Comparing physiological mechanisms?!
Comparing physiologically adaptive strategies?!
Comparative molecular biology? !
Much the same as for biology in general:! Relationship between animal form and
function! Relationship between maintenance of
complexity and homeostasis! Acquiring and using energy! Environmental constraints! Evolution and adaptation! Biodiversity and uniformity!
Central Themes of Comparative Animal Physiology!
Insights into the Relationships Between "Organisms and Their Environment:!
Animals are adapted to their environments through past evolution.!
The organism is a compromise. The result of natural selection is adequacy (“Just good enough”), not perfection.!
Energy availability and utilization are important constraints on animal function.!
Body temperature regulation is expensive in time and energy. Its alternative (temperature conformity), results in variability in all physiological processes.!
Body size affects nearly every biological variable.! Behavior is an important component of functional
adjustment to the environment. Environmental cues help determine behaviors.!
Hierarchical Organization of Life! Biomolecules and macromolecules! Cells and subcellular components (e.g., organelles, membranes,
and cytoplasmic elements)! Cells/Organisms – individual ‘living things’! Populations –freely-interbreeding "
organisms inhabiting the same place at the"same time!
Species – all organisms that can"actually or potentially interbreed"and produce fertile offspring!
Communities – collections of populations"of different species inhabiting the same place at the same time!
Ecosystems – living organisms (communities) and their non-living environments!
Biosphere – all of Earth’s ecosystems: every part of Earth where life exists!
Most commonly studied by physiologists!
These two individuals share more than 98% of their genomes (perhaps less than 500 of their genes differ)!
Emergent Properties of Life!!Organisms are living systems. Systems are"organized collections of parts. When energy is"applied to systems, then new emergent properties"appear that are more complex than the system’s"collective properties (“the whole is greater than the"sum of its parts”) ! Cells: perform synthesis of large molecules and"
chromosomal replication! Populations: exhibit age structure, genetic diversity,"
natural selection! Species: have reproductive isolating mechanisms (behaviors,
chromosomal or germ cell incompatibilities)! Communities: have coevolutionary relationships between species (e.g.,
competition, predation), and undergo predictable changes with time (succession)!
Ecosystems: recycle nutrients between living organisms and the non-living environment!
Biosphere: living things affect, and are affected by, the Earth’s biogeochemistry and climatic conditions!
Figure 1.1 The study of physiology integrates knowledge at all levels of organization
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PSLY 4210/5210 !Comparative Animal Physiology !Spring 2010!What is ‘Comparative Animal Physiology’?!
Topic 1 – 2!
Environmental Challenges to Organisms’ Survival and Reproduction (Fitness)!
Temperature extremes! Osmotic pressure extremes! Lack of free water! Low partial pressures of oxygen! Trace element deficiencies! Atmospheric/hydrostatic pressure extremes! Radiation! pH!Organisms must adapt to these challenges.!
Figure 1.6 Mixed conformity and regulation in a single species
Body Size is Important in Many Physiological Processes!
Larger animals:! Have fewer predators! Compete more successfully for mates! Produce more offspring! Retain heat better! Resist starvation better!
Use energy at a lower rate per unit mass! Can store more energy!!Many anatomical structures and physiological functions scale with size.!
Figure 1.8 Length of gestation scales as a regular function of body size in mammals
Types of Comparisons Between Species!1)!Convergence/divergence! Animals belonging to distantly related taxa
often evolve adaptations that allow them to have similar modes of life!
Analogous structures and physiological functions:! Form and prior evolutionary history constrains
function! Different embryonic derivation and structural
organization)! Physiological machinery and morphological
structures are totally different!
High degree of "convergence, e.g.,"hummingbirds"and sphinx moths!
Overlapping body sizes, similar body/wing shapes and aerodynamics (both beat their wings in the same “figure-eight”"pattern!
Both hover in front of flowers"to drink nectar!
Example: Flapping Flight "in Birds and Insects!
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PSLY 4210/5210 !Comparative Animal Physiology !Spring 2010!What is ‘Comparative Animal Physiology’?!
Topic 1 – 3!
Hovering is"the most"energetically "expensive"form of flight!
Hummingbirds"and sphinx"moths have"similar energy "consumption"rates!
Example: Flapping Flight "in Birds and Insects!
Bartholomew and Casey (1978); Bartholomew and Lighton (1986)
Figure 1.4 Structures that are similar in gross appearance, functional performance, and adaptive significance can differ dramatically in details of how they are assembled and work
Figure 1.4 Structures that are similar in gross appearance, functional performance, and adaptive significance can differ dramatically in details of how they are assembled and work
No ‘blind spot’
‘Blind spot’
Types of Comparisons Between Species!2) !Adjustments that permit closely related
species to live in dissimilar environments!!Example: sea lions and fur sea lions in equatorial, temperate and Arctic climates!
Pinnipeds are extremely well-adapted to cold: insulated from cold water by combinations of size, subcutaneous fat, and fur, but!
Easily overheated on land! Can die if forced to walk a few hundred meters, even when
overcast and
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PSLY 4210/5210 !Comparative Animal Physiology !Spring 2010!What is ‘Comparative Animal Physiology’?!
Topic 1 – 4!
3) Do related species living in the same difficult environment have similar responses to that environment? Example: desert lizards of the family Iguanidae:"""""!
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!chuckwalla !desert iguana !! Both can feed on dried vegetation and extract water from it.! High temperature tolerances allow longer daily activity: longer
time interval to acquire and digest this low-quality diet.! Similar adaptations for fermentative digestion.! Nasal salt glands to deal with excess Na+/ K+ in diet!
Types of Comparisons Between Species! Types of Comparisons Between Species!4)!How do distantly-related taxa adapt to the
same or similar difficult environment?!Example: flying insects that breed during the winter! Normally, insects at < 0 °C are immobilized.! However, a few unrelated species (a scarab beetle
and several geometrid moths) carry out breeding flights at < 0 °C (presumably to avoid predation).!
Beetles have low wing loading: rapid wing beats raise body temperature to performance levels.!
Moths have high wing loading: can fly with slow wing beats and low energy expenditure.!
Specific Questions Arising from Comparisons Between Species!
Do species comparisons produce merely a series of “adaptive stories”?!
Do species comparisons simply demonstrate that animals can live where they do?!
Does the approach based on species comparisons have adequate analytical paradigms?!
Specific Questions Arising from Comparisons Between Species!
Do species comparisons produce merely a series of “adaptive stories”?! Yes, but these need not be the only
(“trivial”) results! Do species comparisons simply
demonstrate that animals can live where they do?!
Does the approach based on species comparisons have adequate analytical paradigms?!
Specific Questions Arising from Comparisons Between Species!
Do species comparisons produce merely a series of “adaptive stories”?!
Do species comparisons simply demonstrate that animals can live where they do?! Yes, the species comparative approach necessarily
shows this, but again, this need not be a self-answering (“trivial”) question!
The question is more attractive when rephrased as: “What physiological mechanisms allow animals to live where and how they do?”!
Does the approach based on species comparisons have adequate analytical paradigms?!
Specific Questions Arising from Comparisons Between Species!
Do species comparisons produce merely a series of “adaptive stories”?!
Do species comparisons simply demonstrate that animals can live where they do?!
Does the approach based on species comparisons have adequate analytical paradigms?! All scientists need paradigms! As knowledge increases, paradigms change
(essential part of the success of science is that it is self-correcting)!
