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Topic: Endothermy

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	Fish - Wikipedia, the free encyclopedia
		All sharks in the family Lamnidae – shortfin mako, long fin mako, white, porbeagle, and salmon shark – are known to have the capacity for endothermy, and evidence suggests the trait exists in family Alopiidae (thresher sharks).
		The degree of endothermy varies from the billfish, which warm only their eyes and brain, to bluefin tuna and porbeagle sharks who maintain body temperatures elevated in excess of 20 °C above ambient water temperatures.
		Endothermy, though metabolically costly, is thought to provide advantages such as increased contractile force of muscles, higher rates of central nervous system processing, and higher rates of digestion.
	en.wikipedia.org /wiki/Fish (1867 words)

	ANNOTATIONS 20(1)
		Endothermy, the ability to warm the body through metabolic activity, is absent in most fish, but is present in two families of sharks and three families of bony fish.
		The authors compare the distribution of endothermy with a molecular phylogeny based on the DNA sequence of the mitochondrial gene for cytochrome b.
		Their comparison indicates that endothermy occurs independently in each of the three groups of fish, and is not inherited from a common ancestor.
	www.grisda.org /origins/20022.htm (5998 words)

	Warm-blooded dinosaurs?
		At the end of this period and at the beginning of Triassic the climate grew still dryer with very warm day-hours and very cold nights which was due to minimising of carbon dioxide (CO2) in the atmosphere and consequently a decrease of the greenhouse-effect.
		Therefore it was an evolutionary benefit for these animals to evolve the power of endothermy, as this made it possible for them to stay inactive in the heat of the cycad-top and to be active in the coolness on the ground.
		As endothermy is not present, neither in the tuatara and lizards, which descend from the group of diapside reptiles from which the archosaurs originated, nor in crocodiles, the only recent archosaur, it seems little likely that the archosaur-ancestors of the dinosaurs possessed this quality.
	home13.inet.tele.dk /palm/warmweb.htm (2161 words)

	Esa Hohtola: Research
		Endothermy is a novel phenomenon in the evolution of vertebrates (Ruben, 1995).
		This is the basis of endothermy in thermoneutral conditions (Hayes and Garland, 1995).
		Ruben, J. The evolution of endothermy in mammals and birds: From physiology to fossils.
	cc.oulu.fi /~ehohtola/resdata.htm (2572 words)

	Discussions by Yann Oliver
		endothermy opposed to mass homoiothermy) occurred somewhere between thecodonts (the dinosaurs' ancestors) and birds.
		Endothermy could then have emerged three times (in pterosaurs, in some non-birdlike dinosaurs and in birds), or much more probably only once, before the differentiation of pterosaurs and dinosaurs, in which case all dinosaurs (not only the birdlike ones) would be endothermic, as well as pterosaurs.
		It might be that the improved stance go together with endothermy due to a high level of activity, and that a running animal have a need for endothermy, but the causal relationship is not clear.
	www.dinodata.org /Discussions/dino/metabolism.html (2171 words)

	Comments to " Warm-blooded Dinosaurs
		The view of the dinosaurs’ endothermy or ectothermy has been subject to what might be called a "paradigm shift", that is that the general idea of the dinosaurs as cold-blooded reptiles was changed into a general idea of them as warm-blooded, highly active non-reptiles.
		Endothermy in any kind of dinosaur has yet not been proven.
		Later on have many palaeontologists tried to prove the endothermy of dinosaurs in general and the theropods in particular, but - in my opinion - none convincingly.
	home13.inet.tele.dk /palm/warmcom.htm (517 words)

	ePrintsUQ - The Evolution of Endothermy and Its Diversity in Mammals and Birds
		Thus, unlike current models for the evolution of endothermy which assume that hibernation and torpor are specialisations arising from homeothermic ancestry, and therefore irrelevant, we consider that they are central.
		Echdinas have the advantages of endothermy, including the capacity for homeothermic endothermy during incubation, but are very relaxed in their thermoregulatory precision and minimise energetic costs by using ectothermy facultatively when entering short or long term torpor.
		We favor theories about the evolution of endothermy which invoke direct selection for the benefits conferred by warmth, such as expanding daily activity into the night, higher capacities for sustained activity, higher digestion rates, climatic range expansion and, not unrelated, control over incubation temperature and the benefits for parental care.
	eprint.uq.edu.au /archive/00002395 (475 words)

	Evidence for Endothermy?
		Having evolved endothermy and such a heart, the dinosaurs could evolve to larger size and upright posture.
		Only one dinosaur was the ancestor to all birds, and we don't know which one that was for sure (although Archaeopteryx is assumed to be closely related).
		If the change to endothermy occurred just before the origin of birds, then no other dinosaurs would be endothermic.
	www.ucmp.berkeley.edu /diapsids/endothermy.html (1087 words)

	ISGS Dinosaurs Warm or Cold Blooded
		There are, of course, attendant disadvantages to endothermy, not the least of which is the need for very much larger expenditure of energy to maintain elevated metabolic rates, and a commensurate increase in food requirements.
		Endothermy is not an either/or proposition, as the large number of potential physiological mechanisms involved make a wide range of alternatives possible.
		Some authorities suggest that for animals of the size and apparent vigorous lifestyle of dinosaurs, sufficient heat will be generated by the maintenance of high activity levels to make the animals effective endotherms, regardless of the presence or absence of any specific mechanisms.
	www.isgs.uiuc.edu /faq/dino-faqs/pdq236.html (3200 words)

	[No title] (Site not responding. Last check: 2007-10-26)
		There is plenty of evidence supporting both endothermy and ectothermy in dinosaurs.
		Many scientists have come up with hypotheses that dinosaurs were endotherms, but this does not mean that their evidence is not without its problems.
		A final hypothesis for the endothermy of dinosaurs states that because dinosaur bone is more similar to mammalian and avian bone, then dinosaurs were endothermic.
	www.lightlink.com /pri/ed/ICTHOL/ICTHOLrp/37rp.htm (819 words)

	ePrintsUQ - Hibernation By Echidnas In Mild Climates: Hints About The Evolution Of Endothermy?
		Attention is drawn to parallels between the daily/seasonal cycles in the body temperatures of torpidators/hibernators and those seen commonly in reptiles, and to the extent to which thermoregulatory mechanisms in reptiles foreshadow those in mammals and birds.
		A stepwise scenario for the evolution of endothermy is presented, with torpor/hibernation as a central theme.
		In presenting this scenario, we take care to distinguish between pattern and mechanism, recognising that the terms torpor and hibernation, like poikilothermy and homeothermy, are descriptive of patterns, not mechanisms, and that this limitation of the current terminology must be recognised.
	eprint.uq.edu.au /archive/00002087 (358 words)

	Turbinates in Therapsids: Evidence for Late Permian Origins of Mammalian Endothermy (Site not responding. Last check: 2007-10-26)
		In fossil mammals and mammal-like reptiles, the presence and function of turbinates are most readily revealed by the ridges by which they attach to the walls of the nasal cavity.
		The presence of respiratory turbinals in these advanced mammal-like reptiles suggests that the evolution of "mammalian" oxygen consumption rates may have begun as early as the Late Permian, and developed in parallel in therocephalians and cynodonts.
		Full mammalian endothermy may have taken as much as 40 to 50 million years to develop.
	www.cofc.edu /~biology/facultypages/evol1994.html (332 words)

	Thermogenic mechanisms during the development of endothermy in juvenile birds
		The use of regulatory and obligatory heat production mechanisms were studied in juvenile birds during the development of endothermy.
		The development of shivering thermogenesis was studied in the pectoral and gastrocnemius muscles of the altricial domestic pigeon and in three precocial galliforms (Japanese quail, grey partridge and domestic fowl).
		The development of shivering was the determinant for the beginning of endothermy.
	herkules.oulu.fi /isbn9514265424/html/index.html (663 words)

	Singers With Hot Bodies: African Cicadas Reveal New Tricks
		Endothermy permits activity independent of environmental temperatures, and we have found that it occurs in a surprising number of African and New World cicadas.
		First, most cicadas have clear, glassy wings, but platypleurines are unusual in having a mottled colouration pattern on their bodies and beautifully pigmented wings that allow them to hide among the mosses and lichens on the bark, making it difficult for predators to locate the cicada.
		We are now trying to determine how widespread endothermy is in the platypleurine cicadas and what could have led to the evolution of endothermy as a major thermoregulatory strategy.
	www.scienceinafrica.co.za /2003/february/cicadas.htm (1706 words)

	Stanford University Department of Biological Sciences
		The Block lab investigates endothermy in fish including cellular, ecological and evolutionary physiology.
		Research at sea is focused on understanding the movements and physiological ecology of tunas and billfishes to gain insight into the selective advantage of endothermy in fish and habitat utilization.
		Signal cascades initiated by G-protein coupled receptors and egional specialization of function in neurons and the role that localized clusters of ion channels play in the processing of information by the cell.
	www.stanford.edu /dept/biology/faculty_hopkins.html (410 words)

	Circulation and a Wonderful Net
		A fascinating 1993 paper by physiological ecologist Barbara Block and her co-workers examined the phylogeny and retia mirablia of active, warm-bodied teleosts such as tunas and billfishes (which have a retial system that is similar - but not identical - to that found in lamnoid sharks).
		Block et alii's results strongly suggest that the primary selection pressure fostering the evolution of endothermy in these fishes may have been range extension into cold waters rather than increased aerobic activity.
		While energetically expensive, endothermy has enabled some lamnoid sharks to function as effective predators in cold waters, taking advantage of the rich feeding available there.
	www.elasmo-research.org /education/white_shark/rete.htm (1553 words)

	Discover Africa
		Using internal controls, most mammals can maintain their body at about the same temperature even when the temperature around them changes (within limits).
		Endothermy permits animals to be active regardless of the air temperature and allows birds and mammals to remain active during times when or in areas where it would be too hot or too cold for other animals to function.
		The main function of hair is insulation, although it is often colored for use in camouflage or display, is sometimes adapted as a sense organ (for example, whiskers), and is even modified for protection (for example, rhinoceros horn).
	www.calacademy.org /exhibits/africa/discover/nathistory/mammals.htm (668 words)

	Summary of the Metabolism Debate
		There is strong evidence from both sides that dinosaurs in general had a different physiology from either mammals or "typical reptiles." Endothermy did evolve from ectothermy, and birds (endotherms) did evolve from dinosaurs, which we know came from ectothermic ancestors sometime in the distant past.
		Dinosaurs were quite diverse in size and form; their physiologies must have differed as well, just like whales, bats, and horses have different physiologies.
		As long as we do not understand endothermy and how it evolves, we have little chance of understanding what animals were endotherms or not.
	www.ucmp.berkeley.edu /diapsids/summarythermy.html (461 words)

	Cullum - Research Interests
		Interestingly, however, in this case the difference does not persist in lab-reared fish, suggesting that differences in wild-caught fish do not have a genetic basis, and hence that rapid-start performance is not undergoing evolutionary change in these populations.
		Possible mechanisms by which endothermy may have evolved in mammals and birds have been a subject of considerable interest.
		A major assumption of this model is that moderate increases in metabolic rate will necessarily allow animals with reptilian physiology to increase their body temperatures.
	biology.creighton.edu /faculty/cullum/ResearchInterests.html (1041 words)

	Florida Entomologist, v. 78, n. 2, p. 319
		Endothermy was first described in cicadas by Bartholomew and Barnhart (1984) and has recently been described as a mechanism of thermoregulation in cicadas (Sanborn et al., in press).
		The endothermy described here is not simply the result of activity in an isolated, active body region, e.g.
		Endothermy in the Proarna species may serve to increase reproductive fitness by uncoupling reproductive behavior from possible physiological constraints imposed by the environment.
	www.fcla.edu /FlaEnt/fe78p319.html (3689 words)

	Re: Had warm-bloodedness evolve independently in birds and mammals?
		The advantage of endothermy is that it allows an animal to forage for food in places and at times where it would be too cold for an exotherm to move.
		If endothermy in both mammals and birds originated from the same group of animals, then you would expect to see some form of insulation in a line of dinosaurs as well.
		There is some evidence that the ancestors of birds might have been warm-blooded and it has not been established beyond doubt whether endothermy evolved in birds or whether birds evolved from an endotherm.
	www.madsci.org /posts/archives/jun99/928483060.Ev.r.html (509 words)

	Dr. Kathryn Dickson (Site not responding. Last check: 2007-10-26)
		In addition to being the focus of important commercial fisheries throughout the world, tunas (14 species of the fish family Scombridae) are of particular interest to biologists because they are the only teleost fishes known to use metabolic heat to maintain muscle temperatures (Tm) elevated significantly above ambient water temperature (Ta); i.e., they are endothermic.
		In both fish groups, blood vessels arranged as counter-current heat exchangers (retia) conserve heat generated continuously by contraction of red (slow, oxidative) muscle fibers as tunas swim constantly to maintain hydrostatic equilibrium and to ram ventilate.
		The goal of my current research is to test directly for the first time the hypothesis that maintenance of high Tm in tunas results in increased swimming performance.
	stromboli.fullerton.edu /kdickson.html (292 words)

	HMS Student Papers 1997 - Anatomical adaptations for endothermy: retia mirabilia in the salmon shark, Lamna ditropis (Site not responding. Last check: 2007-10-26)
		HMS Student Papers 1997 - Anatomical adaptations for endothermy: retia mirabilia in the salmon shark, Lamna ditropis
		Gross anatomical studies of three subjects revealed that the mechanism for such endothermy is facilitated by counter-current heat exchangers common in other lamnids and scombrids.
		We propose that the combined efficiency of these retial systems allows L. ditropis to occupy its icy niche, the most polar of any shark.
	library.stanford.edu /depts/miller/student_papers/1997_2.html (278 words)

	Dino Land Paleontology Interviews: Dr. Robert T. Bakker
		Ostrom, and his brilliant Yale student Bakker, led the charge that resulted in the now nearly universally accepted idea that birds evolved from dinosaurs, and the still hotly debated idea that some dinosaurs may have been warmblooded.
		While it is still debated just who first proposed this heavily debated idea of dinosaur endothermy, Bakker seems to think that he did, pointing to a paper on the issue that first appeared in 1968.
		While the endothermy idea has brought Bakker fame, he has also spent decades conducting countless field expeditions that have resulted in numerous new species.
	www.geocities.com /CapeCanaveral/Galaxy/8152/robertbakker.html (1680 words)

	Origin and Evolution of Sleep: Roles of Vision and Endothermy
		By this means, processing of visual information in central regions of the brain may have been maintained at a sufficiently low level to allow adequate concomitant dynamic stabilization.
		As endothermy evolved, the skeletal muscle hypotonia of primitive sleep may have become insufficient to prevent sleep-disrupting skeletal muscle contractions during `non-utilitarian' dynamic stabilization of motor circuitry at the accompanying higher body temperatures and metabolic rates.
		Selection against such disruption during dynamic stabilization of motor circuitry may have led to the inhibition of skeletal muscle tone during a portion of primitive sleep, the portion designated as "rapid-eye-movement sleep." Many marine mammals that are active almost continuously engage only in unihemispheric non-rapid-eye-movement sleep.
	www.obee.ucla.edu /Faculty/Kavanau/originofsleep.html (584 words)

	Lecture 36 (Site not responding. Last check: 2007-10-26)
		Many of these lines of evidence are consistent with endothermy in at least some theropods and ornithopods, but most evidence does not support endothermy in the other dinosaurs.
		The inferred social behavior (display structures, parental care, herding, etc.) of some dinosaurs is consistent with, but not strong evidence for, their endothermy.
		It has been argued that in an endotherm oxygen isotope ratios should vary little between the limb bones and the bones of the core of the body because the body temperature is nearly the same at both locations.
	www.unc.edu /courses/2000fall/geol018-001/Lecture36.html (923 words)

	John A. Ruben, Zoology - Oregon State University
		Currently, research in my lab focuses on a variety of intriguing problems associated with the evolution of endothermy, in birds, mammals and their ancestors.
		With a view toward providing broad new insight into questions such as when and why endothermy evolved, ongoing NSF-funded research in my laboratory ranges from CAT-scan analysis of 200 million year old fossil mammal-like reptile skulls to sophisticated analysis of songbird respiratory physiology.
		1995 Ruben, J.A. The evolution of endothermy: From physiology to fossils.
	oregonstate.edu /~rubenj (333 words)

	The Evolution of Nasal Turbinates and Mammalian Endothermy (Site not responding. Last check: 2007-10-26)
		The Evolution of Nasal Turbinates and Mammalian Endothermy
		The data support the conclusion that turbinates did not evolve primarily as an adaptation to particular environmental conditions, but in relation to high ventilation rates, typical of all mammals.
		Complex turbinates appear to be an ancient attribute of mammals, and may have originated among the therapsid ancestors of mammals, in relation to elevated ventilation rates and the evolution of endothermy.
	www.cofc.edu /~biology/facultypages/pal1992.html (134 words)

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