Comparative physiology

Comparative physiologyis asubdisciplineofphysiologythat studies and exploits the diversity of functional characteristics of various kinds oforganisms.It is closely related toevolutionary physiologyandenvironmental physiology.Many universities offer undergraduate courses that cover comparative aspects of animal physiology. According toClifford Ladd Prosser,"Comparative Physiology is not so much a defined discipline as a viewpoint, a philosophy."

History

Originally, as narrated in a recent history of the field,physiologyfocused primarily on human beings, in large part from a desire to improvemedicalpractices. When physiologists first began comparing differentspeciesit was sometimes out of simple curiosity to understand how organisms work but also stemmed from a desire to discover basic physiological principles. This use of specific organisms convenient to study specific questions is known as theKrogh Principle.

Methodology

C. Ladd Prosser,a founder of modern comparative physiology, outlined a broad agenda for comparative physiology in his 1950 edited volume (see summary and discussion inGarlandand Carter):

1. To describe how different kinds of animals meet their needs.

This amounts to cataloging functional aspects of biological diversity, and has recently been criticized as "stamp collecting" with the suggestion that the field should move beyond that initial, exploratory phase.

2. The use of physiological information to reconstructphylogeneticrelationships of organisms.

In principle physiological information could be used just as morphological information orDNAsequence is used to measure evolutionary divergence of organisms. In practice, this has rarely been done, for at least four reasons:

• physiology doesn't leave manyfossilcues,
• it can't be measured onmuseumspecimens,
• it is difficult to quantify as compared with morphology or DNA sequences, and
• physiology is more likely to be adaptive than DNA, and so subject to parallel andconvergent evolution,which confuses phylogenetic reconstruction.

3. To elucidate how physiology mediates interactions between organisms and their environments.

This is essentiallyphysiological ecologyor ecological physiology.

4. To identify "model systems" for studying particular physiological functions.

Examples of this include using squid giant axons to understand general principles of nerve transmission, using rattlesnake tail shaker muscles for measurement of in vivo changes in metabolites (because the whole animal can be put in an NMR machine),and the use of ectothermic poikilotherms to study effects of temperature on physiology.

5. To use the "kind of animal" as an experimental variable.

"While other branches of physiology use such variables as light, temperature, oxygen tension, and hormone balance, comparative physiology uses, in addition, species or animal type as a variable for each function."

25 years later, Prosser put things this way: "I like to think of it as that method in physiology which uses kind of organism as one experimental variable."

Comparative physiologists often study organisms that live in "extreme"environments(e.g., deserts) because they expect to find especially clear examples of evolutionary adaptation.One example is the study of water balance in desert-inhabiting mammals, which have been found to exhibit kidney specializations.

Similarly, comparative physiologists have been attracted to "unusual" organisms, such as very large or small ones. As an example, of the latter,hummingbirdshave been studied. As another example,giraffehave been studied because of their long necks and the expectation that this would lead to specializations related to the regulation ofblood pressure.More generally,ectothermicvertebrateshave been studied to determine howbloodacid-base balanceandpHchange asbody temperaturechanges.

Funding

In the United States, research in comparative physiology is funded by both theNational Institutes of Healthand theNational Science Foundation.

Societies

A number of scientific societies feature sections on comparative physiology, including:

• American Physiological Society
• Australian & New Zealand Society for Comparative Physiology & Biochemistry
• Canadian Society of Zoologists
• Japanese Society for Comparative Physiology and Biochemistry
• Society for Integrative and Comparative Biology
• Society for Experimental Biology

Biographies

Knut Schmidt-Nielsen(1915–2007) was a major figure in vertebrate comparative physiology, serving on the faculty atDuke Universityfor many years and training a large number of students(obituary).He also authored several books, including an influential text, all known for their accessible writing style.

Grover C. Stephens(1925–2003) was a well-known invertebrate comparative physiologist, serving on the faculty of theUniversity of Minnesotauntil becoming the founding chairman of the Department of Organismic Biology at theUniversity of California at Irvinein 1964. He was the mentor for numerous graduate students, many of whom have gone on to further build the field(obituary).He authored several books and in addition to being an accomplished biologist was also an accomplished pianist and philosopher.

Some journals that publish articles in comparative animal physiology

• American Journal of Physiology - Regulatory, Integrative and Comparative Physiology
• Annual Review of Physiology
• Comparative Biochemistry and Physiology
• Ecological and Evolutionary Physiology(formerly Physiological and Biochemical Zoology)
• Integrative and Comparative Biology
• Journal of Comparative Physiology
• Journal of Experimental Biology

See also

• August Krogh
• Claude Bernard
• Comparative anatomy
• Ecophysiology
• Evolutionary physiology
• Human physiology
• John Speakman
• Knut Schmidt-Nielsen
• Krogh Principle
• Lancelot Hogben
• Peter Hochachka
• Phylogenetic comparative methods
• Physiology
• Raymond B. Huey
• Theodore Garland Jr.

Further reading

• Anctil, M. 2022. Animal as machine - The quest to understand how animals work and adapt. McGill-Queen's University Press, Montreal & Kingston, London, Chicago.
• Barrington, E. J. W. 1975. Comparative physiology and the challenge of design. Journal of Experimental Zoology 194:271-286.
• Clark, A. J. 1927. Comparative physiology of the heart. Cambridge University Press, London.
• Dantzler, W. H., ed. 1997. Handbook of physiology. Section 13: comparative physiology. Vol. I. Oxford Univ. Press, New York.
• Dantzler, W. H., ed. 1997. Handbook of physiology. Section 13: comparative physiology. Vol. II. Oxford Univ. Press, New York. viii + 751-1824 pp.
• Feder, M. E., A. F. Bennett, W. W. Burggren, and R. B. Huey, eds. 1987. New directions in ecological physiology. Cambridge Univ. Press, New York. 364 pp.
• Garland, T. Jr.,and P. A. Carter. 1994. Evolutionary physiology. Annual Review of Physiology 56:579-621.PDFArchived2021-04-12 at theWayback Machine
• Gibbs, A. G. (1999). "Laboratory selection for the comparative physiologist".Journal of Experimental Biology.202(Pt 20): 2709–2718.doi:10.1242/jeb.202.20.2709.PMID10504307.
• Gilmour, K. M.; Wilson, R. W.; Sloman, K. A. (2005). "The integration of behaviour into comparative physiology".Physiological and Biochemical Zoology.78(5): 669–678.doi:10.1086/432144.PMID16047293.S2CID586358.
• Gordon, M. S., G. A. Bartholomew, A. D. Grinnell, C. B. Jorgensen, and F. N. White. 1982. Animal physiology: principles and adaptations. 4th ed. MacMillan, New York. 635 pages.
• Greenberg, M. J., P. W. Hochachka, and C. P. Mangum, eds. 1975. New directions in comparative physiology and biochemistry. Journal of Experimental Zoology 194:1-347.
• Hochachka, P. W., and G. N. Somero. 2002. Biochemical adaptation — mechanism and process in physiological evolution. Oxford University Press. 478 pp.
• Mangum, C. P., and P. W. Hochachka. 1998. New directions in comparative physiology and biochemistry: mechanisms, adaptations, and evolution. Physiological Zoology 71:471-484.
• Moyes, C. D., and P. M. Schulte. 2006. Principles of animal physiology. Pearson Benjamin Cummings, San Francisco. 734 pp.
• Prosser, C. L., ed. 1950. Comparative animal physiology. W. B. Saunders Co., Philadelphia. ix + 888 pp.
• Randall, D., W. Burggren, and K. French. 2002. Eckert animal physiology: mechanisms and adaptations. 5th ed. W. H. Freeman and Co., New York. 736 pp. + glossary, appendices, index.
• Ross, D. M. (1981). "Illusion and reality in comparative physiology".Canadian Journal of Zoology.59(11): 2151–2158.doi:10.1139/z81-291.
• Schmidt-Nielsen, K. 1972. How animals work. Cambridge University Press, Cambridge.
• Schmidt-Nielsen, K. 1984. Scaling: why is animal size so important? Cambridge University Press, Cambridge. 241 pp.
• Schmidt-Nielsen, K. 1997. Animal physiology: adaptation and environment. 5th ed. Cambridge University Press, Cambridge. ix + 607 pp.
• Schmidt-Nielsen, K. 1998. The camel's nose: memoirs of a curious scientist. 352 pp. The Island Press.Review
• Somero, G. N. 2000. Unity in Diversity: A perspective on the methods, contributions, and future of comparative physiology. Annual Review of Physiology 62:927-937.
• Stephens, G.C.; Schinske, R.A. (1961). "Uptake of amino acids by marine invertebrates".Limnology and Oceanography.6(2): 175–181.Bibcode:1961LimOc...6..175S.doi:10.4319/lo.1961.6.2.0175.
• Stephens, G.C. (1982)."Recent progress in the study of" Die Ernährung der Wassertiere und der Stoffhaushalt der Gewasser "".American Zoologist.22(3): 611–619.doi:10.1093/icb/22.3.611.
• Manahan, D.T.;Wright, S.H.;Stephens, G.C.;Rice, M.A.(1982)."Transport of dissolved amino acids by the mussel,Mytilus edulis:Demonstration of net uptake from seawater by HPLC analysis ".Science.215(4537): 1253–1255.doi:10.1126/science.215.4537.1253.PMID17757542.S2CID36756710.
• Swallow, J. G.;Garland, T. Jr.(2005)."Selection experiments as a tool in evolutionary and comparative physiology: insights into complex traits - An introduction to the symposium".Integrative and Comparative Biology.45(3): 387–390.doi:10.1093/icb/45.3.387.PMID21676784.
• Willmer, P., G. Stone, and I. Johnston. 2005. Environmental physiology of animals. Second edition. Blackwell Science, Oxford, U.K. xiii + 754 pp.