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57-530: (Redirected from Topór ) Not to be confused with Torpor . [REDACTED] Look up topor  or topór in Wiktionary, the free dictionary. Topor may refer to: Places [ edit ] Topor (Barclayville) , a village in Barclayville township, Grand Kru County, Liberia Topór, a nature reserve in Łuków Forest , Poland Topór, Mińsk County ,

114-478: A black bear , enter torpor and switch to multi-day cycles rather than rely on a circadian rhythm. However, it is seen that both captive and wild bears express similar circadian rhythms when entering torpor. Bears entering torpor in a simulated den with no light expressed normal but low functioning rhythms. The same was observed in wild bears denning in natural areas. The function of circadian rhythms in black, brown , and polar bears suggest that their system of torpor

171-480: A body temperature 12 °C lower than normal. This reduction in metabolism allows it to conserve 30% of fat stores amassed from the previous day. Torpor can be a strategy of animals with unpredictable food supplies. For example, high-latitude living rodents use torpor seasonally when not reproducing. These rodents use torpor as means to survive winter and live to reproduce in the next reproduction cycle when food sources are plentiful, separating periods of torpor from

228-408: A common proto-hibernating ancestor of birds and mammals, the ability to hibernate or go through torpor would have been lost in most larger mammals and birds. Hibernation would be less favored in larger animals because as animals increase in size, the surface area to volume ratio decreases, and it takes less energy to keep a high internal body temperature, and thus hibernation becomes unnecessary. There

285-667: A heat-producing brown adipose tissue as a mechanism to accelerate rewarming. The mechanism of marsupial arousal is unknown, but appears not to rely on brown adipose tissue. The evolution of torpor likely accompanied the development of homeothermy . Animals capable of maintaining a body temperature above ambient temperature when other members of its species would not have a fitness advantage. Benefits of maintaining internal temperatures include increased foraging time and less susceptibility to extreme drops in temperature. This adaptation of increasing body temperature to forage has been observed in small nocturnal mammals when they first wake up in

342-406: A later point. This difference in development is evidence, though inconclusive, that they evolved by slightly different mechanisms and thus at different times. As reptiles are ectothermic, having no system to deal with cold temperatures would be deadly in many environments. Reptilian winter dormancy, or brumation, likely evolved to help reptiles survive colder conditions. Reptiles that are dormant in

399-425: A list of people with that name Topór coat of arms , a Polish coat of arms TopoR , an automated topological router for printed circuit boards See also [ edit ] All pages with titles containing Topor Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Topor . If an internal link led you here, you may wish to change

456-505: A means to survive in their shoreline habitat, where water and oxygen levels vary with the tide. Other animals able to survive long periods with very little or no oxygen include goldfish , red-eared sliders , wood frogs , and bar-headed geese . The ability to survive hypoxic or anoxic conditions is not closely related to endotherm hibernation. Some animals can literally survive winter by freezing. For example, some fish , amphibians , and reptiles can naturally freeze and then "wake" up in

513-529: A modest decline in body temperature (3–5 °C) compared with the much larger decreases (often 32 °C or more) seen in other hibernators. Many researchers thought that their deep sleep was not comparable with true, deep hibernation, but this theory was refuted by research in 2011 on captive black bears and again in 2016 in a study on brown bears . Hibernating bears are able to recycle their proteins and urine, allowing them to stop urinating for months and to avoid muscle atrophy . They stay hydrated with

570-529: A periodic internal clock, which is likely triggered by cooler outside temperatures, as shown in the Texas horned lizard ( Phrynosoma cornutum ). One mechanism that reptiles use to survive hibernation, hypercapnic acidosis (the buildup of carbon dioxide in the blood), is also present in mammal hibernation. This is likely an example of convergent evolution . Hypercapnic acidosis evolved as a mechanism to slow metabolism and also interfere with oxygen transport so that oxygen

627-418: A physiological state wherein the body temperature drops to near ambient temperature, and heart and respiration rates slow drastically. The typical winter season for obligate hibernators is characterized by periods of torpor interrupted by periodic, euthermic arousals, during which body temperatures and heart rates are restored to more typical levels. The cause and purpose of these arousals are still not clear;

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684-415: A response to stressors from the environment. A good example of the differences between these two types of hibernation can be seen in prairie dogs . The white-tailed prairie dog is an obligate hibernator, while the closely related black-tailed prairie dog is a facultative hibernator. While hibernation has long been studied in rodents (namely ground squirrels ), no primate or tropical mammal

741-442: A seasonal diapause, where many of their biological functions end up paired with a seasonal rhythm within the organism. This is a very similar mechanism to the evolution of insect migration, where instead of bodily functions like metabolism getting paired with seasonal indicators, movement patterns would be paired with seasonal indicators. While most animals that go through winter dormancy lower their metabolic rates, some fish, such as

798-607: A village in Gmina Mrozy, Mińsk County, Masovian Voivodeship, Poland Topór, Węgrów County , a village in Gmina Stoczek, Węgrów County, Masovian Voivodeship, Poland Films [ edit ] Topor and Me , a short film directed by Dutch actress Sylvia Kristel (1952–2012) Topor père et fils , a 1993 documentary by Belgian director Henri Xhonneux (1945–1995) Other [ edit ] Topor (headgear) , Bengali Hindu wedding headwear Topor (surname) , including

855-409: A way to dramatically cut the cost of a human expedition to Mars by putting the crew in extended torpor for 90 to 180 days. Traveling while hibernating would reduce astronauts' metabolic functions and minimize requirements for life support during multi-year missions. Hibernation Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation

912-484: Is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate . It is most commonly used to pass through winter months – called overwintering . Although traditionally reserved for "deep" hibernators such as rodents , the term has been redefined to include animals such as bears and is now applied based on active metabolic suppression rather than any absolute decline in body temperature. Many experts believe that

969-462: Is driven by environmental cues, but arousal is driven by physiological cues. Ancient people believed that swallows hibernated, and ornithologist Gilbert White documented anecdotal evidence in his 1789 book The Natural History of Selborne that indicated the belief was still current in his time. It is now understood that the vast majority of bird species typically do not hibernate, instead utilizing shorter periods of torpor . One known exception

1026-402: Is evidence that hibernation evolved separately in marsupials and placental mammals, though it is not settled. That evidence stems from development, where as soon as young marsupials from hibernating species are able to regulate their own heat, they have the capability to hibernate. In contrast, placental mammals that hibernate first develop homeothermy , only developing the ability to hibernate at

1083-559: Is evolutionarily advanced. Torpor has been shown to be a strategy of small migrant birds to preserve their body energy stores . Hummingbirds, resting at night during migration, were observed to enter torpor which helped to conserve fat stores during migration or cold nights at high altitude. This strategy of using torpor to preserve energy stores, such as fat, has also been observed in wintering chickadees. Black-capped chickadees , living in temperate forests of North America, do not migrate south during winter. The chickadee can maintain

1140-433: Is not used up and can still reach tissues in low oxygen periods of dormancy. Seasonal diapause, or arthropod winter dormancy, seems to be plastic and quickly evolving, with large genetic variation and strong effects of natural selection present as well as having evolved many times across many clades of arthropods. As such, there is very little phylogenetic conservation in the genetic mechanism for diapause. Particularly

1197-439: Is referred to as diapause. Some researchers and members of the public use the term brumate to describe winter dormancy of reptiles, but the more general term hibernation is believed adequate to refer to any winter dormancy. Many insects, such as the wasp Polistes exclamans and the beetle Bolitotherus , exhibit periods of dormancy which have often been referred to as hibernation, despite their ectothermy. Botanists may use

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1254-492: Is the common poorwill ( Phalaenoptilus nuttallii ), for which hibernation was first documented by Edmund Jaeger . Because they cannot actively down-regulate their body temperature or metabolic rate, ectothermic animals (including fish, reptiles, and amphibians) cannot engage in obligate or facultative hibernation. They can experience decreased metabolic rates associated with colder environments or low oxygen availability ( hypoxia ) and exhibit dormancy (known as brumation). It

1311-425: Is thought to have originally evolved in three stages. The first is development of neuroendocrine control over bodily functions, the second is pairing of that to environmental changes—in this case metabolic rates decreasing in response to colder temperatures—and the third is the pairing of these controls with reliable seasonal indicators within the arthropod, like biological timers. From these steps, arthropods developed

1368-606: The cunner , do not. Instead, they do not actively depress their base metabolic rate, but instead they simply reduce their activity level. Fish that undergo winter dormancy in oxygenated water survive via inactivity paired with the colder temperature, which decreases energy consumption, but not the base metabolic rate that their bodies consume. But for the Antarctic yellowbelly rockcod ( Notothenia coriiceps ) and for fish that undergo winter dormancy in hypoxic conditions, they do suppress their metabolism like other animals that are dormant in

1425-412: The metabolic water that is produced in sufficient quantities to satisfy the water needs of the bear. They also do not eat or drink while hibernating, but live off their stored fat. Despite long-term inactivity and lack of food intake, hibernating bears are believed to maintain their bone mass and do not suffer from osteoporosis . They also increase the availability of certain essential amino acids in

1482-556: The QT interval changed for both typical hibernators and the bears from summer to winter. This 1977 study was one of the first evidences used to show that bears are hibernators. In a 2016 study, wildlife veterinarian and associate professor at Inland Norway University of Applied Sciences , Alina L. Evans, researched 14 brown bears over three winters. Their movement, heart rate , heart rate variability , body temperature, physical activity, ambient temperature, and snow depth were measured to identify

1539-452: The active part of their day, such animals maintain normal body temperature and activity levels, but their metabolic rate and body temperature drop during a portion of the day (usually night) to conserve energy. Some animals seasonally go into long periods of inactivity, with reduced body temperature and metabolism, made up of multiple bouts of torpor. This is known as hibernation if it occurs during winter or aestivation if it occurs during

1596-561: The ancestor of birds and mammals onto land introduced them to seasonal pressures that would eventually become hibernation. This is true for all clades of animals that undergo winter dormancy; the more prominent the seasons are, the longer the dormant period tends to be on average. Hibernation of endothermic animals has likely evolved multiple times, at least once in mammals—though it is debated whether or not it evolved more than once in mammals—and at least once in birds. In both cases, hibernation likely evolved simultaneously with endothermy, with

1653-567: The animal to restore its available energy sources or to initiate an immune response. Hibernating Arctic ground squirrels may exhibit abdominal temperatures as low as −2.9 °C (26.8 °F), maintaining sub-zero abdominal temperatures for more than three weeks at a time, although the temperatures at the head and neck remain at 0 °C (32 °F) or above. Facultative hibernators enter hibernation only when either cold-stressed, food-deprived, or both, unlike obligate hibernators, who enter hibernation based on seasonal timing cues rather than as

1710-481: The animal to study key hibernation proteins (HP). Researchers have studied how to induce hibernation in humans. The ability to hibernate would be useful for a number of reasons, such as saving the lives of seriously ill or injured people by temporarily putting them in a state of hibernation until treatment can be given. For space travel, human hibernation is also under consideration, such as for missions to Mars . Anthropologists are also studying whether hibernation

1767-554: The bears' heart rate variability dropped dramatically, indirectly suggesting metabolic suppression is related to their hibernation. Two months before the end of hibernation, the bears' body temperature starts to rise, unrelated to heart rate variability but rather driven by the ambient temperature. The heart rate variability only increases around three weeks before arousal and the bears only leave their den once outside temperatures are at their lower critical temperature. These findings suggest that bears are thermoconforming and bear hibernation

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1824-442: The common spiny mouse it spends more time in a torpid state. A drop in temperature from torpor has been shown to reduce the ability of parasites to reproduce. In temperate zones, the reproductive rates of ectoparasites on bats decrease when the bats enter torpor. In regions where bats don't undergo torpor, the parasites maintain a consistent reproductive rate throughout the year. In 2013, SpaceWorks Engineering began researching

1881-455: The drivers of the start and end of hibernation for bears. This study built the first chronology of both ecological and physiological events from before the start to the end of hibernation in the field. This research found that bears would enter their den when snow arrived and ambient temperature dropped to 0 °C. However, physical activity, heart rate, and body temperature started to drop slowly even several weeks before this. Once in their dens,

1938-623: The earliest suggested instance of hibernation being in Thrinaxodon , an ancestor of mammals that lived roughly 252 million years ago. The evolution of endothermy allowed animals to have greater levels of activity and better incubation of embryos, among other benefits for animals in the Permian and Triassic periods. In order to conserve energy, the ancestors of birds and mammals would likely have experienced an early form of torpor or hibernation when they were not using their thermoregulatory abilities during

1995-469: The evening. Although homeothermy lends advantages such as increased activity levels, small mammals and birds maintaining an internal body temperature spend up to 100 times more energy in low ambient temperatures compared to ectotherms. To cope with this challenge, these animals maintain a much lower body temperature, staying just over ambient temperature rather than at normal operating temperature. This reduction in body temperature and metabolic rate allows

2052-449: The hole is poorly insulated, the lemur's body temperature fluctuates widely, passively following the ambient temperature; if well insulated, the body temperature stays fairly constant and the animal undergoes regular spells of arousal. Dausmann found that hypometabolism in hibernating animals is not necessarily coupled with low body temperature. Historically it was unclear whether or not bears truly hibernate, since they experience only

2109-425: The last 500 years. Torpor enables animals to reduce energy requirements allowing them to better survive harsh conditions. Interspecific competition occurs when two species require the same resource for energy production. Torpor increases fitness in the case of inter-specific competition with the nocturnal common spiny mouse . When the golden spiny mouse experiences reduced food availability by diet overlap with

2166-459: The late 20th century, since it is dissimilar from hibernation seen in rodents. Obligate hibernators are animals that spontaneously, and annually, enter hibernation regardless of ambient temperature and access to food. Obligate hibernators include many species of ground squirrels , other rodents , European hedgehogs and other insectivores , monotremes , and marsupials . These species undergo what has been traditionally called "hibernation":

2223-604: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Topor&oldid=1183465501 " Categories : Disambiguation pages Place name disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Torpor Animals that undergo daily torpor include birds (even tiny hummingbirds , notably Cypselomorphae ) and some mammals, including many marsupial species, rodent species (such as mice ), and bats . During

2280-666: The mother hibernates or shortly afterwards. For example, female black bears go into hibernation during the winter months in order to give birth to their offspring. The pregnant mothers significantly increase their body mass prior to hibernation, and this increase is further reflected in the weight of the offspring. The fat accumulation enables them to provide a sufficiently warm and nurturing environment for their newborns. During hibernation, they subsequently lose 15–27% of their pre-hibernation weight by using their stored fats for energy. Ectothermic animals also undergo periods of metabolic suppression and dormancy , which in many invertebrates

2337-400: The muscle, as well as regulate the transcription of a suite of genes that limit muscle wasting. A study by G. Edgar Folk, Jill M. Hunt and Mary A. Folk compared EKG of typical hibernators to three different bear species with respect to season, activity and dormancy, and found that the reduced relaxation (QT) interval of small hibernators was the same for the three bear species. They also found

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2394-414: The processes of daily torpor and hibernation form a continuum and utilise similar mechanisms. The equivalent during the summer months is aestivation . Hibernation functions to conserve energy when sufficient food is not available. To achieve this energy saving, an endothermic animal decreases its metabolic rate and thereby its body temperature. Hibernation may last days, weeks, or months—depending on

2451-547: The prolonged survival of animals capable of entering torpid states. In 2020, scientists reported evidence of the torpor in Lystrosaurus living ~250 Mya in Antarctica – the oldest evidence of a hibernation-like state in a vertebrate animal. Slowing metabolic rate to conserve energy in times of insufficient resources is the primarily noted purpose of torpor. This conclusion is largely based on laboratory studies where torpor

2508-556: The question of why hibernators may return periodically to normal body temperatures has plagued researchers for decades, and while there is still no clear-cut explanation, there are multiple hypotheses on the topic. One favored hypothesis is that hibernators build a " sleep debt " during hibernation, and so must occasionally warm up to sleep. This has been supported by evidence in the Arctic ground squirrel . Other theories postulate that brief periods of high body temperature during hibernation allow

2565-540: The reproduction period. The eastern long-eared bat uses torpor during winter and is able to arouse and forage during warm periods. Some animals use torpor during their reproductive cycle, as seen in unpredictable habitats. They experience the cost of a prolonged reproduction period but the payoff is survival to be able to reproduce at all. It is suggested that this daily torpor use may have allowed survival through mass extinction events . Heterotherms make up only four out of 61 mammals confirmed to have gone extinct over

2622-536: The species, ambient temperature, time of year, and the individual's body-condition. Before entering hibernation, animals need to store enough energy to last through the duration of their dormant period, possibly as long as an entire winter. Larger species become hyperphagic , eating a large amount of food and storing the energy in their bodies in the form of fat deposits. In many small species, food caching replaces eating and becoming fat. Some species of mammals hibernate while gestating young, which are born either while

2679-434: The spring. These species have evolved freeze tolerance mechanism such as antifreeze proteins . Hibernation induction trigger (HIT) proteins isolated from mammals have been used in the study of organ recovery rates. One study in 1997 found that delta 2 opioid and hibernation induction trigger (HIT) proteins were not able to increase the recovery rate of heart tissue during ischemia. While unable to increase recovery rates at

2736-420: The summer. Daily torpor, on the other hand, is not seasonally dependent and can be an important part of energy conservation at any time of year. Torpor is a well-controlled thermoregulatory process and not, as previously thought, the result of switching off thermoregulation. Marsupial torpor differs from non-marsupial mammalian ( eutherian ) torpor in the characteristics of arousal. Eutherian arousal relies on

2793-488: The term "seed hibernation" to refer to a form of seed dormancy . There is a variety of definitions for terms that describe hibernation in mammals, and different mammal clades hibernate differently. The following subsections discuss the terms obligate and facultative hibernation. The last two sections point out in particular primates, none of whom were thought to hibernate until recently, and bears, whose winter torpor had been contested as not being "true hibernation" during

2850-798: The time of ischemia, the protein precursors were identified to play a role in the preservation of veterinary organ function. Recent advances in recombinant protein technology make it possible for scientists to manufacture hibernation induction trigger (HIT) proteins in the laboratory without the need for animal euthanasia. Bioengineering of proteins can aid in the protection of vulnerable populations of bears and other mammals that produce valuable proteins. Protein sequencing of HIT proteins, such as α 1-glycoprotein-like 88 kDa hibernation-related protein HRP, contributes to this research pool. A study in 2014 utilizes recombinant technology to construct, express, purify, and isolate animal proteins (HP-20, HP-25, and HP-27) outside of

2907-444: The timing and extent of the seasonal diapause seem particularly variable, currently evolving as a response to climate change . As typical with hibernation, it evolved after the increased influence of seasonality as arthropods colonized terrestrial environments as a mechanism to keep energy costs low, particularly in harsher than normal environments, as well as being a good way to time the active or reproductive periods in arthropods. It

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2964-440: The transition from ectothermy to endothermy. This is opposed to the previously dominant hypothesis that hibernation evolved after endothermy in response to the emergence of colder habitats. Body size also had an effect on the evolution of hibernation, as endotherms which grow large enough tend to lose their ability to be selectively heterothermic, with bears being one of very few exceptions. After torpor and hibernation diverged from

3021-403: The winter tend to have higher survival rates and slower aging. Reptiles evolved to exploit their ectothermy to deliberately cool their internal body temperatures. As opposed to mammals or birds, which will prepare for their hibernation but not directly cause it through their behavior, reptiles will trigger their own hibernation through their behavior. Reptiles seek out colder temperatures based on

3078-422: Was known to hibernate until the discovery of hibernation in the fat-tailed dwarf lemur of Madagascar, which hibernates in tree holes for seven months of the year. Malagasy winter temperatures sometimes rise to over 30 °C (86 °F), so hibernation is not exclusively an adaptation to low ambient temperatures. The hibernation of this lemur is strongly dependent on the thermal behaviour of its tree hole: If

3135-505: Was observed to follow food deprivation. There is evidence for other adaptive functions of torpor where animals are observed in natural contexts: Animals that can enter torpor rely on biological rhythms such as circadian and circannual rhythms to continue natural functions. Different animals will manage their circadian rhythm differently, and in some species it's seen to completely stop (such as in European hamsters ). Other organisms, such as

3192-494: Was once thought that basking sharks settled to the floor of the North Sea and became dormant, but research by David Sims in 2003 dispelled this hypothesis, showing that the sharks traveled long distances throughout the seasons, tracking the areas with the highest quantity of plankton . Epaulette sharks have been documented to be able to survive for three hours without oxygen and at temperatures of up to 26 °C (79 °F) as

3249-414: Was possible in early hominid species. As the ancestors of birds and mammals colonized land, leaving the relatively stable marine environments, more intense terrestrial seasons began playing a larger role in animals' lives. Some marine animals do go through periods of dormancy, but the effect is stronger and more widespread in terrestrial environments. As hibernation is a seasonal response, the movement of

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