Genetic engineering called genetic modification or genetic manipulation, is the direct manipulation of an organism's genes using biotechnology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms. New DNA is obtained by either isolating and copying the genetic material of interest using recombinant DNA methods or by artificially synthesising the DNA. A construct is created and used to insert this DNA into the host organism; the first recombinant DNA molecule was made by Paul Berg in 1972 by combining DNA from the monkey virus SV40 with the lambda virus. As well as inserting genes, the process can be used to remove, or "knock out", genes; the new DNA can be targeted to a specific part of the genome. An organism, generated through genetic engineering is considered to be genetically modified and the resulting entity is a genetically modified organism; the first GMO was a bacterium generated by Herbert Boyer and Stanley Cohen in 1973.
Rudolf Jaenisch created the first GM animal when he inserted foreign DNA into a mouse in 1974. The first company to focus on genetic engineering, was founded in 1976 and started the production of human proteins. Genetically engineered human insulin was produced in 1978 and insulin-producing bacteria were commercialised in 1982. Genetically modified food has been sold with the release of the Flavr Savr tomato; the Flavr Savr was engineered to have a longer shelf life, but most current GM crops are modified to increase resistance to insects and herbicides. GloFish, the first GMO designed as a pet, was sold in the United States in December 2003. In 2016 salmon modified with a growth hormone were sold. Genetic engineering has been applied in numerous fields including research, industrial biotechnology and agriculture. In research GMOs are used to study gene function and expression through loss of function, gain of function and expression experiments. By knocking out genes responsible for certain conditions it is possible to create animal model organisms of human diseases.
As well as producing hormones and other drugs genetic engineering has the potential to cure genetic diseases through gene therapy. The same techniques that are used to produce drugs can have industrial applications such as producing enzymes for laundry detergent and other products; the rise of commercialised genetically modified crops has provided economic benefit to farmers in many different countries, but has been the source of most of the controversy surrounding the technology. This has been present since its early use. Although there is a scientific consensus that available food derived from GM crops poses no greater risk to human health than conventional food, GM food safety is a leading concern with critics. Gene flow, impact on non-target organisms, control of the food supply and intellectual property rights have been raised as potential issues; these concerns have led to the development of a regulatory framework, which started in 1975. It has led to an international treaty, the Cartagena Protocol on Biosafety, adopted in 2000.
Individual countries have developed their own regulatory systems regarding GMOs, with the most marked differences occurring between the US and Europe. Genetic engineering is a process that alters the genetic structure of an organism by either removing or introducing DNA. Unlike traditional animal and plant breeding, which involves doing multiple crosses and selecting for the organism with the desired phenotype, genetic engineering takes the gene directly from one organism and inserts it in the other; this is much faster, can be used to insert any genes from any organism and prevents other undesirable genes from being added. Genetic engineering could fix severe genetic disorders in humans by replacing the defective gene with a functioning one, it is an important tool in research. Drugs and other products have been harvested from organisms engineered to produce them. Crops have been developed that aid food security by increasing yield, nutritional value and tolerance to environmental stresses; the DNA can be introduced directly into the host organism or into a cell, fused or hybridised with the host.
This relies on recombinant nucleic acid techniques to form new combinations of heritable genetic material followed by the incorporation of that material either indirectly through a vector system or directly through micro-injection, macro-injection or micro-encapsulation. Genetic engineering does not include traditional breeding, in vitro fertilisation, induction of polyploidy and cell fusion techniques that do not use recombinant nucleic acids or a genetically modified organism in the process. However, some broad definitions of genetic engineering include selective breeding. Cloning and stem cell research, although not considered genetic engineering, are related and genetic engineering can be used within them. Synthetic biology is an emerging discipline that takes genetic engineering a step further by introducing artificially synthesised material into an organism. Plants, animals or micro organisms that have been changed through genetic engineering are termed genetically modified organisms or GMOs.
If genetic material from another species is added to the host, the resulting organism is called transgenic. If genetic material from the same species or a species that can breed with the host is used the resulting organism is called cisgenic. If genetic engineering is used to r
Dragonsblood is a science fiction novel by Todd McCaffrey in the Dragonriders of Pern series that his mother Anne McCaffrey initiated in 1967. Published in 2005, this was the first with the nineteenth in the series. Todd's solo contribution followed two years after the first published collaboration between mother and son, Dragon's Kin. Although set only a decade Dragonsblood is not a sequel. During the next few years, the McCaffreys co-wrote two sequels to their Dragon's Kin and Todd completed two sequels to his Dragonsblood. All of Todd's novels are set just before or at the beginning of the "Third Pass", about 500 years after human settlement on Pern and 2000 years before the "Ninth Pass" events chronicled in most of Anne McCaffrey's Pern books. Dragonsblood features an epidemic that strikes fire-lizards first, dragons; the people of Pern have regressed since its settlement by colonists from Earth and have lost the knowledge and equipment to handle such a bio-medical crisis. In Moreta: Dragonlady of Pern and Nerilka's Story, Anne McCaffrey had featured a plague that decimates humans and passes among mammals.
That happened 1000 years in Pern history. Occasional chapters of Dragonsblood are set soon after the end of the First Pass of the Red Star, nearly 450 years before most of the action. There the elderly Wind Blossom, a geneticist and daughter of the legendary Kitti Ping, is bemoaning the gradual loss of manufactured items and the technology to create them, she and her ex-protégé Tieran are startled by two fire-lizards who fall from the sky. One, a gold, dies upon arrival, they nurse a bronze, back to health, using the last of the antibiotics. Not knowing if the fire-lizard's sickness is contagious, they quarantine it. Tieran adopts the fire lizard and names him Grenn – the name found on the harness he was wearing. Further investigation of the decorations on Grenn’s harness leads to the incredible conclusion that he is from the future. Since fire-lizards provided the genetic basis that Kitti Ping used to build the Thread-fighting dragons, they speculate that this future affliction of fire-lizards might be fatal to dragons, and, confirmed when a dead gold dragonet appears – one sickened by the same future disease.
The dragon's body is destroyed. In order to save the dragons of the future, Wind Blossom and Tieran devise a plan to educate someone from the future in genetics and the scientific knowledge to isolate the disease and devise a cure, they create hidden rooms in Benden Weyr and fill them with instructions and equipment to educate that future person. Tieran believes that both the fire-lizard and dragon came from the same woman in the future, since both had similar harness decorations and only women impress gold dragons, he further believes that she has some connection with himself and Wind Blossom – a connection that both dragon and fire lizards followed. He leaves a small souvenir for her in the hidden rooms. About 400 years at the beginning of the 3rd Pass of the Red Star, a talented young sketch artist and amateur healer Lorana is hitching a ride across the ocean to the newly built Half-Circle seahold. In a desperate attempt to save her two fire-lizards Grenn and Garth during a storm at sea, she orders them to leave her and believes they are dead.
She is found washed up on the beach by dragonriders from Benden Weyr and recovers just in time to impress Arith, a gold dragon. Meanwhile and fire-lizards are falling sick to a disease with a 100% mortality rate. Fire-lizards are banned from the Weyrs and many die due to the disease. Lorana, who can hear and speak with any dragon, thus sharing in the death of each dragon, frantically scours records in hopes of finding some sort of clue or help towards fighting the disease, she gets them open. The recorded voice of Wind Blossom invites her and her companions to enter and learn what they need to find a cure. Lorana’s dragon Arith goes between and dies when a combination of the disease and an injection of watch-wher genetic material wreak havoc with her system. Despite the tragedy of losing Arith and the added burden of over a thousand dragon deaths, Lorana learns how to use such items as a microscope and a genetic sampler to find the disease and create a cure, she can only make a single dose which she injects into the pregnant gold Minith, in hopes that the cure will be passed onto future dragon generations.
Minith, her irritable rider Tullea and several others are sent between times to the past to give them time to recover. They return with enough cure to save the rest of the dragons. An older and kinder Tullea gives Lorana an ancient locket she had swiped from the first of the hidden rooms. In it are a piece of Arith’s harness and pictures of Wind Blossom and her fire-lizard Grenn; the fire-lizard banishment lead to the absence of fire-lizards by Moreta’s time and their "re-discovery" by F'nor and Menolly several hundred years later. The story brings back a time shortly after that of Dragonsdawn, introducing the use of drums as a means of communication across distances that figures prominently in the Harper Hall trilogy and other earlier stories. Fire-lizards used to be the main relayers of messages, but with their banishment, people turned to drums to spread news; the loss of technology leads to a shift towards an oral tradition and the creation and use of Teaching Songs. Wind Blossom was trained by her mother Kitti Ping
Dragonflight is a science fiction novel by the American-Irish author Anne McCaffrey. It is the first book in the Dragonriders of Pern series. Dragonflight was first published by Ballantine Books in July 1968, it is a fix-up of novellas, including two which made McCaffrey the first woman writer to win a Hugo and Nebula Award. In 1987, Locus: The magazine of the science fiction & fantasy field ranked Dragonflight at number nine among the 33 "All-Time Best Fantasy Novels", based on a poll of subscribers. Two components of Dragonflight were award-winning novellas published by Analog science fiction magazine; the first segment, Weyr Search, illustrated by John Schoenherr, had been the cover story for the October 1967 issue. The second segment, appeared in two parts, beginning in December 1967. Weyr Search features a young woman named Lessa being recruited to establish a telepathic bond with a queen dragon at its hatching, thus becoming a dragonrider, the leader of a Weyr community on the fictional planet Pern.
Dragonrider features the growth of Lessa's queen dragon and their training together. Analog editor John W. Campbell asked "to see dragons fighting Thread", Pern's menace from space, he suggested time travel. In response, McCaffrey wrote a third story titled "Crack Dust, Black Dust", not published separately, but provided crucial material for the novel. Dragonflight takes place in the far future on Pern, a planet colonized by humans; the colonists had intended to adopt a low-technology agrarian lifestyle, but were forced to move more after they encountered the deadly Thread raining down from the sky. By harnessing and riding the indigenous, fire-breathing dragons, the colonists destroyed the Thread in the skies over Pern, creating pockets of safety over its surface, before it was able to burrow into the land and breed. Humanity managed to find equilibrium and began to create a thriving culture and economy expanding right across Pern's northern continent. However, when this narrative begins, an unusually long interval between Thread attacks has caused the general population to dismiss the threat as myth and withdraw support from the Weyrs where dragons are bred and trained.
By the time of this narrative, only one Weyr remains. Dragons are telepathic and are capable of forming a lifelong bond with one particular human in a process called Impression. Tradition, established thousands of years before the narrative, dictates that selected young humans with empathetic and telepathic talents are taken to the Hatching Grounds as candidates for Impression; the dragons come in several colors which correlate with their sizes. Bronzes, the largest males, are by tradition the only ones who compete to win the queens in their mating flights; the green females are banned from breeding as they produce less talented dragons. The golden queens are not only the largest dragons, they hold a subtle control over their dragon communities Weyrs; the Queen sets out on a Mating Flight, pursued by several bronze males. And the passion of the male dragon and queen mating up in the air can telepathically transfer itself to their male and female human partners, inducing them to a passionate human lovemaking.
Dragonflight is the story of Lessa, the sole survivor of the noble ruling family of Ruatha Hold on the northern continent of Pern. When the rest of her family is killed by a cruel usurper, she survives by disguising herself as a drudge through adopting a slovenly appearance, but by using her hereditary telepathic abilities to make others see her as far older and less attractive than she is, her only friend is a watch-wher, a somewhat telepathic animal related to dragons, that guards the Hold. Lessa psychically influences other Hold workers to do less than their best work, or to become clumsy or inefficient, in order to sabotage Ruatha as part of her strategy to make it economically unproductive, so that Fax will renounce it and she can retake her Hold. F'lar, wingleader at Benden Weyr, rider of the bronze dragon Mnementh, finds Lessa while searching for candidates to impress a new queen dragon; the current queen has a batch including a crucial golden egg. After killing Fax in single combat, following the rules of the Pernese code duello, he realises that she manipulated him to kill Fax and engineered Fax's renouncement.
F'lar recognizes that Lessa possesses both unusually strong psychic abilities and great strength of will. He recognizes her potential to be the strongest Weyrwoman in recent history, the path to his own leadership at Benden Weyr. F'lar convinces a reluctant Lessa to give up her birthright as Lord Holder of Ruatha Hold for the larger domain of the dragonweyr and she agrees to pass the title on to Fax's newborn son. F'lar takes Lessa to Benden Weyr, where she Impresses the queen hatchling Ramoth and becomes the Weyrwoman, the new co-leader of the last active Weyr. On Ramoth's first mating flight, Mnementh catches her, by Weyr tradition, this makes F'lar the Weyrleader. One Weyr by itself is not enough to defend the planet.
Dragon's Kin is a science fiction novel by the American-Irish author Anne McCaffrey and her son Todd McCaffrey. Published by Del Rey Books in 2003, it is the eighteenth book in the Dragonriders of Pern series and the first with Todd as co-author. Dragon's Kin may be considered the first of a trilogy by the McCaffreys, preceding Dragon's Fire and Dragon Harper; the three books feature Kindan as a boy and young man, about 500 years after landing on Pern. Anne McCaffrey created Pern in the novella Weyr Search. In 2001 and 2002 she published her fifteenth Pern novel and second collection of short stories. Dragon's Kin was their first collaborative work. Todd recalled that a Del Rey editor in the 1990s "pitched it to me that someone ought to continue Mum’s legacy when she was no longer able. At the time I had misgivings and no story ideas."Previously, as Todd Johnson, he had contributed the chapter "Training and Fighting Dragons" to The Dragonlover's Guide to Pern. Mother and son had discussed Pern and its setting for years, she had suggested that he "write the military science fiction prequels" to the colonization, but that never progressed far.
They co-authored four Pern novels and, as of December 2011, Todd has done three alone. All are set just before and during the "Third Pass", about 500 years after human settlement on Pern and 2000 years before the "Ninth Pass" events chronicled in most of Anne McCaffrey's Pern books; the story tells how the people of the fictional planet Pern discover the special abilities of the watch-whers or whers, a distant relative of the dragons. Subsequently, these beasts are used in mines to warn miners of gas pockets and to locate stranded miners, should there be a cave-in; the story begins some years before the 3rd Pass in a mining camp. There, the reader is introduced to a young boy Kindan. During a mining cave-in, Kindan loses his entire family as well as Dask, is adopted by the Master Harper Zist, who begins to train him to be both an entertainer and a spy, something that Harpers do; this is how Kindan learns that the camp is divided into two parties, Natalon's and his uncle Tarik's. Meanwhile, the camp is without a watch-wher and minor accidents keep delaying the work.
Despite the protests from Tarik and his group, Natalon decides to trade an entire winter's worth of coal for a chance for Kindan to ask a queen watch-wher for an egg. He begins the difficult task of raising a nocturnal animal; as no records exist on how to raise or train the watch-wher, Kindan has no clue but is luckily aided by the mysterious Nuella. Together, they train Kisk and, in the process, learn a great deal about this species; this proves to be vital as, towards the end of the novel, Kisk's abilities will save many lives, including that of the camp leader, Natalon. McCaffrey, Todd. Dragonholder: The Life and Dreams of Anne McCaffrey by her son. New York: Ballantine. ISBN 978-0-345-42217-0. Nye, Jody Lynn; the Dragonlover's Guide to Pern. With Anne McCaffrey. New York: Ballantine. ISBN 978-0-345-35424-2. Dragon's Kin title listing at the Internet Speculative Fiction Database
Telepathy is the purported vicarious transmission of information from one person to another without using any known human sensory channels or physical interaction. The term was coined in 1882 by the classical scholar Frederic W. H. Myers, a founder of the Society for Psychical Research, has remained more popular than the earlier expression thought-transference. Telepathy experiments have been criticized for lack of proper controls and repeatability. There is no convincing evidence that telepathy exists, the topic is considered by the scientific community to be pseudoscience. According to historians such as Roger Luckhurst and Janet Oppenheim the origin of the concept of telepathy in Western civilization can be tracked to the late 19th century and the formation of the Society for Psychical Research; as the physical sciences made significant advances, scientific concepts were applied to mental phenomena, with the hope that this would help to understand paranormal phenomena. The modern concept of telepathy emerged in this context.
Psychical researcher Eric Dingwall criticized SPR founding members Frederic W. H. Myers and William F. Barrett for trying to "prove" telepathy rather than objectively analyze whether or not it existed. In the late 19th century, the magician and mentalist, Washington Irving Bishop would perform "thought reading" demonstrations. Bishop ascribed his powers to muscular sensitivity. Bishop was investigated by a group of scientists including the editor of the British Medical Journal and the psychologist Francis Galton. Bishop performed several feats such as identifying a selected spot on a table and locating a hidden object. During the experiment Bishop required physical contact with a subject, he would hold the wrist of the helper. The scientists concluded that Bishop was not a genuine telepath but using a trained skill to detect ideomotor movements. Another famous thought reader was the magician Stuart Cumberland, he was famous for performing blindfolded feats such as identifying a hidden object in a room that a person had picked out or asking someone to imagine a murder scene and attempt to read the subject's thoughts and identify the victim and reenact the crime.
Cumberland claimed to possess no genuine psychic ability and his thought reading performances could only be demonstrated by holding the hand of his subject to read their muscular movements. He came into dispute with psychical researchers associated with the Society for Psychical Research who were searching for genuine cases of telepathy. Cumberland argued that both telepathy and communication with the dead were impossible and that the mind of man cannot be read through telepathy, but only by muscle reading. In the late 19th century the Creery Sisters were tested by the Society for Psychical Research and believed to have genuine psychic ability. However, during a experiment they were caught utilizing signal codes and they confessed to fraud. George Albert Smith and Douglas Blackburn were claimed to be genuine psychics by the Society for Psychical Research but Blackburn confessed to fraud: For nearly thirty years the telepathic experiments conducted by Mr. G. A. Smith and myself have been accepted and cited as the basic evidence of the truth of thought transference......the whole of those alleged experiments were bogus, originated in the honest desire of two youths to show how men of scientific mind and training could be deceived when seeking for evidence in support of a theory they were wishful to establish.
Between 1916 and 1924, Gilbert Murray conducted 236 experiments into telepathy and reported 36% as successful, however, it was suggested that the results could be explained by hyperaesthesia as he could hear what was being said by the sender. Psychologist Leonard T. Troland had carried out experiments in telepathy at Harvard University which were reported in 1917; the subjects produced below chance expectations. Arthur Conan Doyle and W. T. Stead were duped into believing Julius and Agnes Zancig had genuine psychic powers. Both Doyle and Stead wrote. In 1924, Julius and Agnes Zancig confessed that their mind reading act was a trick and published the secret code and all the details of the trick method they had used under the title of Our Secrets!! in a London newspaper. In 1924, Robert H. Gault of Northwestern University with Gardner Murphy conducted the first American radio test for telepathy; the results were negative. One of their experiments involved the attempted thought transmission of a chosen number, out of 2010 replies none were correct.
In February 1927, with the co-operation of the British Broadcasting Corporation, V. J. Woolley, at the time the Research Officer for the SPR, arranged a telepathy experiment in which radio listeners were asked to take part; the experiment involved'agents' thinking about five selected objects in an office at Tavistock Square, whilst listeners on the radio were asked to identify the objects from the BBC studio at Savoy Hill. 24, 659 answers were received. The results revealed no evidence for telepathy. A famous experiment in telepathy was recorded by the American author Upton Sinclair in his book Mental Radio which documents Sinclair's test of psychic abilities of Mary Craig Sinclair, his second wife, she attempted to duplicate 290 pictures. Sinclair claimed Mary duplicated 65 of them, with 155 "partial successes" and 70 failures. However, these experiments were not condu
Anne Inez McCaffrey was an American-born writer who emigrated to Ireland and was best known for the Dragonriders of Pern science fiction series. Early in McCaffrey's 46-year career as a writer, she became the first woman to win a Hugo Award for fiction and the first to win a Nebula Award, her 1978 novel The White Dragon became one of the first science-fiction books to appear on the New York Times Best Seller list. In 2005 the Science Fiction and Fantasy Writers of America named McCaffrey its 22nd Grand Master, an annual award to living writers of fantasy and science fiction, she was inducted by the Science Fiction Hall of Fame on 17 June 2006. She received the Robert A. Heinlein Award for her work in 2007. Anne Inez McCaffrey was born in Cambridge, the second of three children of Anne Dorothy and Col. George Herbert McCaffrey, she had two brothers: Kevin Richard McCaffrey. Her father had Irish and English ancestry, her mother was of Irish descent, she attended Stuart Hall, graduated from Montclair High School in Montclair, New Jersey.
In 1947 she graduated cum laude from Radcliffe College with a degree in Slavonic languages and Literature. In 1950 she married Horace Wright Johnson, who shared her interests in music and ballet, they had three children: Alec Anthony, born 1952. Except for a short time in Düsseldorf, the family lived for most of a decade in Wilmington, Delaware, they moved to Sea Cliff, Long Island in 1965, McCaffrey became a full-time writer. McCaffrey served a term as secretary-treasurer of the Science Fiction Writers of America from 1968 to 1970. In addition to handcrafting the Nebula Award trophies, her responsibilities included production of two monthly newsletters and their distribution by mail to the membership. McCaffrey emigrated to Ireland with her two younger children in 1970, weeks after filing for divorce. Ireland had exempted resident artists from income taxes, an opportunity that fellow science-fiction author Harry Harrison had promptly taken and helped to promote. McCaffrey's mother soon joined the family in Dublin.
The following spring, McCaffrey was guest of honour at her first British science-fiction convention. There she met British reproductive biologist Jack Cohen, who would be a consultant on the science of Pern. McCaffrey had had two short stories published during the 1950s; the first was written in 1952. It earned a $100 prize in Science-Fiction Plus, her second story, "The Lady in the Tower", was published in The Magazine of Fantasy and Science Fiction by editor Robert P. Mills and published again by editor Judith Merril for The Year's Greatest Science Fiction. McCaffrey said "she thought of the story when wishing herself alone, like a lady in an ivory tower". Judith Merril matched McCaffrey with her long-time literary agent Virginia Kidd and invited her to the Milford Writer's Workshop, where participants each brought a story to be critiqued. After her first Milford workshop in 1959 she worked on "The Ship Who Sang", the story which began the Brain & Brawn Ship series. At the story's end, the spaceship Helva sings "Taps" for her human partner.
Decades McCaffrey's son Todd called it "almost an elegy to her father". In interviews between 1994 and 2004, she considered it her favourite. "I put much of myself into it: myself and the troubles I had in accepting my father's death and a troubled marriage."McCaffrey wrote two more "Ship" stories and began her first novel. Regarding her motivation for Restoree, her son recalled her saying, "I was so tired of all the weak women screaming in the corner while their boyfriends were beating off the aliens. I wouldn't have been—I'd've been in there swinging with something or kicking them as hard as I could". McCaffrey explained. Regarding her 1969 Decision at Doona, her son recalled that he was directed to lower his voice in his fourth-grade school play when his mother was in the auditorium; that inspired the Doona story, which opens on "an overcrowded planet where just talking too loud made you a social outcast". As a settler on Doona, the boy talker has a priceless talent. McCaffrey made a fast start in Ireland, completing for 1971 publication Dragonquest and two Gothic novels for Dell, The Mark of Merlin and The Ring of Fear.
With a contract for The White Dragon, her writing stalled. During the next few years the family moved several times in the Dublin area and struggled to make ends meet, supported by child-care payments and meager royalties; the young-adult book market provided a crucial opportunity. Editor Roger Elwood sought short contributions for anthologies, McCaffrey started the Pern story of Menolly, she delivered "The Smallest Dragonboy" for $154, four stories which became The Crystal Singer. Futura Publications in London signed her to write books about dinosaurs for children. Editor Jean E. Karl at Atheneum Books sought to attract more female readers to science fiction and solicited "a story for young women in a different part of Pern". McCaffrey completed Menolly's story as Dragonsong and contracted for a sequel before its publication in 1976; the tales of Menolly are continued in Dragonsinger: Harper of Pern, Dragondrums as the "Harper Hall Trilogy". With a contract
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures have developed senses of hearing and specially adapted eyesight; such traits can help animals such as the Helicoverpa zea moths avoid predators. Some animals, such as cats and ferrets, have eyes that can adapt to both low-level and bright day levels of illumination. Others, such as bushbabies and bats, can function only at night. Many nocturnal creatures including tarsiers and some owls have large eyes in comparison with their body size to compensate for the lower light levels at night. More they have been found to have a larger cornea relative to their eye size than diurnal creatures to increase their visual sensitivity: in the low-light conditions. Nocturnality helps wasps, such as avoid hunting in intense sunlight. Diurnal animals, including squirrels and songbirds, are active during the daytime.
Crepuscular species, such as rabbits, skunks and hyenas, are erroneously referred to as nocturnal. Cathemeral species, such as fossas and lions, are active both at night. While it is difficult to say which came first, nocturnality or diurnality, there is a leading hypothesis out in the evolutionary biology community. Known as the "bottleneck theory", it postulates that millions of years ago in the Mesozoic era, many ancestors of modern-day mammals evolved nocturnal characteristics in order to avoid contact with the numerous diurnal predators. A recent study attempts to answer the question as to why so many modern day mammals retain these nocturnal characteristics though they are not active at night; the leading answer is that the high visual acuity that comes with diurnal characteristics isn't needed anymore due to the evolution of compensatory sensory systems, such as a heightened sense of smell and more astute auditory systems. In a recent study extinct elephant birds and modern day nocturnal kiwi bird skulls were examined to recreate their brain and skull formation.
They indicated that olfactory bulbs were much larger in comparison to their optic lobes, indicating they both have a common ancestor who evolved to function as a nocturnal species, decreasing their eyesight in favor of a better sense of smell. The anomaly to this theory were anthropoids, who appeared to have the most divergence from nocturnality than all organisms examined. While most mammals didn't exhibit the morphological characteristics expected of a nocturnal creature and birds fit in perfectly. A larger cornea and pupil correlated well with whether these two classes of organisms were nocturnal or not. Being active at night is a form of niche differentiation, where a species' niche is partitioned not by the amount of resources but by the amount of time. Hawks and owls can hunt the same field or meadow for the same rodents without conflict because hawks are diurnal and owls are nocturnal; this means. Nocturnality is a form of an adaptation to avoid or enhance predation. One of the reasons that lions prefer to hunt at night is that many of their prey species have poor night vision.
Many species of small rodents, such as the Large Japanese Field Mouse, are active at night because most of the dozen or so birds of prey that hunt them are diurnal. There are many diurnal species. For example, many seabirds and sea turtles only gather at breeding sites or colonies at night to reduce the risk of predation to themselves and/or their offspring. Nocturnal species take advantage of the night time to prey on species that are used to avoiding diurnal predators; some nocturnal fish species will use the moonlight to prey on zooplankton species that come to the surface at night. Some species have developed unique adaptations. Bats are famous for using echolocation to hunt down their prey, using sonar sounds to capture them in the dark. Another reason for nocturnality is avoiding the heat of the day; this is true in arid biomes like deserts, where nocturnal behavior prevents creatures from losing precious water during the hot, dry daytime. This is an adaptation. One of the reasons that lions prefer to hunt at night is to conserve water.
Many plant species native to arid biomes have adapted so that their flowers only open at night when the sun's intense heat cannot wither and destroy their moist, delicate blossoms. These flowers are pollinated by another creature of the night. Climate-change and the change in global temperatures has led to an increasing amount of diurnal species to push their activity patterns closer towards crepuscular or nocturnal behavior; this adaptive measure allows species to avoid the heat of the day, without having to leave that particular habitat. The exponential increase in human expansion and technological advances in the last few centuries has had a major effect on nocturnal animals, as well as diurnal species; the causes of these can be traced to distinct, sometimes overlapping areas: light pollution and spatial disturbance. Light pollution is a major issue for nocturnal species, the impact continues to increase as electricity reaches parts of the world that had no access. Species in the tropics are more affected by this due to the change in their constant light patterns, but temperate species relying on day-night triggers for behavioral patterns are affected as well.
Many diurnal species see the benefit of a "longer day", allowin