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96-517: The term originated in the mid-1960s in the wake of a film version of H. G. Wells 's The Time Machine that depicted flower-bestowing, communal people of the future in a story characterized by antiwar themes. American political activists like Allen Ginsberg and Abbie Hoffman advocated the giving of flowers as a means of peaceful protest. Images of flower-wielding protesters at the 1967 Pentagon March, such as Marc Riboud 's image of Jan Rose Kasmir titled The Ultimate Confrontation: The Flower and

192-479: A ( non-silent ) mutation , which is almost certain to be deleterious. It therefore behooves sexual creatures to avoid mates sporting rare or unusual features ( koinophilia ). Sexual populations therefore rapidly shed rare or peripheral phenotypic features, thus canalizing the entire external appearance, as illustrated in the accompanying image of the African pygmy kingfisher , Ispidina picta . This uniformity of all

288-569: A ceiling so that natural light could be used instead of costly artificial lighting. The look of the Morlocks was designed by Wah Chang . With a budget of under $ 1 million, the film could not be shot on location in London. Live-action scenes were filmed from May 25 to June 30, 1959, in Culver City, California , with the backgrounds often filled in with matte paintings and models. Some of

384-585: A combination sequel - documentary short , Time Machine: The Journey Back , directed by Clyde Lucas, was produced. In its third section, Michael J. Fox talks about his experience with the DeLorean sports car time machine from Back to the Future . In the short's final section, written by screenwriter David Duncan , Rod Taylor, Alan Young, and Whit Bissell reprise their roles from the original 1960 film. Citations Sources Speciation Speciation

480-671: A common ancestor may be unclear or unknown; a collection of three such species is referred to as a "trichotomy". Polyploidy is a mechanism that has caused many rapid speciation events in sympatry because offspring of, for example, tetraploid x diploid matings often result in triploid sterile progeny. However, among plants, not all polyploids are reproductively isolated from their parents, and gene flow may still occur, such as through triploid hybrid x diploid matings that produce tetraploids, or matings between meiotically unreduced gametes from diploids and gametes from tetraploids (see also hybrid speciation ). It has been suggested that many of

576-419: A concept discredited by (for example) George C. Williams , John Maynard Smith and Richard Dawkins as selectively disadvantageous to the individual. The resolution to Darwin's second dilemma might thus come about as follows: If sexual individuals are disadvantaged by passing mutations on to their offspring, they will avoid mutant mates with strange or unusual characteristics. Mutations that affect

672-423: A distinct phenotype . This phenotype can also be fitter than the parental lineage and as such natural selection may then favor these individuals. Eventually, if reproductive isolation is achieved, it may lead to a separate species. However, reproductive isolation between hybrids and their parents is particularly difficult to achieve and thus hybrid speciation is considered an extremely rare event. The Mariana mallard

768-698: A full-size time machine. George travels forward in time, first in small increments, and then to September, 1917. He meets Filby's son, James, who says Filby died in a war . George returns to the time machine and stops in June, 1940 during the Blitz , finding himself in the midst of " a new war ". A disillusioned George then travels to August, 1966. People are rushing to fallout shelters as air raid sirens are blaring. An elderly James Filby urges George to take cover. George barely makes it back to his time machine as an "atomic satellite" detonates, destroying London and causing

864-470: A likely mechanism, but found it problematic. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric , peripatric , parapatric , and sympatric . Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion. Rapid sympatric speciation can take place through polyploidy , such as by doubling of chromosome number;

960-425: A local volcanic eruption that buries the ruins. The approaching lava rises, cools, and hardens, trapping George as he travels far into the future, waiting for the rock to erode. Eventually the lava wears away, revealing a lush, unspoiled landscape. George stops on October 12, 802,701, near the base of a sphinx . He encounters young men and women wearing simple clothing gathered by a stream. One woman, carried off by

1056-583: A love interest. He was also unimpressed by the production values, writing that the model sets "don't touch the lowest-price Lionel train". Richard L. Coe of The Washington Post wrote that with the exception of the "gooey" love interest, "the tale is an engrossing one, boasting adroit camera tricks by Paul C. Vogel and an exceptionally easy, likable performance of the Time Traveler by Taylor. The youngsters will like this, and their elders will be kept wide awake". The Monthly Film Bulletin wrote that

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1152-645: A niche in which it has an advantage over its competitors, a new species, or subspecies, will have come into being. In geological terms, this will be an abrupt event. A resumption of avoiding mutant mates will thereafter result, once again, in evolutionary stagnation. In apparent confirmation of this punctuated equilibrium view of evolution, the fossil record of an evolutionary progression typically consists of species that suddenly appear, and ultimately disappear, hundreds of thousands or millions of years later, without any change in external appearance. Graphically, these fossil species are represented by lines parallel with

1248-417: A non-native species, were introduced. This apple-feeding population normally feeds only on apples and not on the historically preferred fruit of hawthorns . The current hawthorn feeding population does not normally feed on apples. Some evidence, such as that six out of thirteen allozyme loci are different, that hawthorn flies mature later in the season and take longer to mature than apple flies; and that there

1344-415: A relic of infection by Wolbachia bacteria. An alternative explanation is that these observations are consistent with sexually-reproducing animals being inherently reluctant to mate with individuals whose appearance or behavior is different from the norm. The risk that such deviations are due to heritable maladaptations is high. Thus, if an animal, unable to predict natural selection's future direction,

1440-425: A resource gradient, a large number of separate species evolve, each exquisitely adapted to a very narrow band on that gradient, each species will, of necessity, consist of very few members. Finding a mate under these circumstances may present difficulties when many of the individuals in the neighborhood belong to other species. Under these circumstances, if any species' population size happens, by chance, to increase (at

1536-434: A species to split into two different species. He mapped out how it might be possible for sections of chromosomes to relocate themselves in a genome. Those mobile sections can cause sterility in inter-species hybrids, which can act as a speciation pressure. In theory, his idea was sound, but scientists long debated whether it actually happened in nature. Eventually a competing theory involving the gradual accumulation of mutations

1632-460: A spinning clock and a solar disk . In a meta -concept touch, a brass plate on the time machine's instrument display panel identifies its inventor as "H. George Wells", though the Time Traveler is identified only as "George" in dialogue. In Wells' original story, the protagonist is referred to only as the "Time Traveler". As a means to cut costs, the dome habitat of the Eloi was constructed without

1728-469: A view known as punctuated equilibrium . (See diagram, and Darwin's dilemma .) Evolution can be extremely rapid, as shown in the creation of domesticated animals and plants in a very short geological space of time, spanning only a few tens of thousands of years. Maize ( Zea mays ), for instance, was created in Mexico in only a few thousand years, starting about 7,000 to 12,000 years ago. This raises

1824-505: A weekend, where it fermented in high temperatures, creating a "foul stench" in the air when it was released. Released multiple times on Beta and VHS video cassette, Capacitance Electronic Disc (CED), and both letterboxed and open matte LaserDisc , the film was released on DVD in October 2000 and on Blu-ray Disc in July 2014 from Warner Home Video . An original film score CD

1920-415: Is a gene flow between two populations, strong differential selection may impede assimilation and different species may eventually develop. Habitat differences may be more important in the development of reproductive isolation than the isolation time. Caucasian rock lizards Darevskia rudis , D. valentini and D. portschinskii all hybridize with each other in their hybrid zone ; however, hybridization

2016-442: Is an unknown species. George bids his guests good evening. Filby returns shortly thereafter to find George and his time machine gone. His housekeeper, Mrs. Watchett, notes that nothing is missing except three books that she is unable to identify. Filby speculates that George has returned to the distant future to help the Eloi build a new civilization. When Mrs. Watchett wonders if George will ever return, Filby remarks that "he has all

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2112-415: Is as follows: The Time Machine received generally mixed reviews upon release. Bosley Crowther of The New York Times wrote a mixed review, praising the "familiar polish and burnish" of the production values but finding that "the drama, for all its invention, is creaky and a bit passé. (Apparently there has still been no contact with other planets in 800,000 A.D.) And the mood, while delicately wistful,

2208-508: Is called homoploid hybrid speciation. It is considered very rare but has been shown in Heliconius butterflies and sunflowers . Polyploid speciation, which involves changes in chromosome number, is a more common phenomenon, especially in plant species. Theodosius Dobzhansky , who studied fruit flies in the early days of genetic research in 1930s, speculated that parts of chromosomes that switch from one location to another might cause

2304-494: Is conditioned to produce the fittest offspring possible, it will avoid mates with unusual habits or features. Sexual creatures then inevitably group themselves into reproductively isolated species. Few speciation genes have been found. They usually involve the reinforcement process of late stages of speciation. In 2008, a speciation gene causing reproductive isolation was reported. It causes hybrid sterility between related subspecies. The order of speciation of three groups from

2400-457: Is little evidence of interbreeding (researchers have documented a 4–6% hybridization rate) suggests that sympatric speciation is occurring. Reinforcement, also called the Wallace effect , is the process by which natural selection increases reproductive isolation. It may occur after two populations of the same species are separated and then come back into contact. If their reproductive isolation

2496-479: Is not all nature in confusion instead of the species being, as we see them, well defined? This dilemma can be described as the absence or rarity of transitional varieties in habitat space. Another dilemma, related to the first one, is the absence or rarity of transitional varieties in time. Darwin pointed out that by the theory of natural selection "innumerable transitional forms must have existed", and wondered "why do we not find them embedded in countless numbers in

2592-472: Is not so flippant or droll as it might be in a fiction as fanciful and flighty as this one naturally is". A generally positive review in Variety praised the special effects as "fascinating" and wrote that "Rod Taylor definitely establishes himself as one of the premium young talents on today's screen", but faulted the pacing of the film, finding that "things slow down to a walk" once the protagonist arrives in

2688-569: Is often proposed to play a significant role in peripatric speciation. Case studies include Mayr's investigation of bird fauna; the Australian bird Petroica multicolor ; and reproductive isolation in populations of Drosophila subject to population bottlenecking. In parapatric speciation, there is only partial separation of the zones of two diverging populations afforded by geography; individuals of each species may come in contact or cross habitats from time to time, but reduced fitness of

2784-600: Is only revealed through new hybridization. Such incompatibilities cause lower fitness in hybrids regardless of the ecological environment, and are thus intrinsic, although they can originate from the adaptation to different environments. The accumulation of such incompatibilities increases faster and faster with time, creating a "snowball" effect. There is a large amount of evidence supporting this theory, primarily from laboratory populations such as Drosophila and Mus , and some genes involved in incompatibilities have been identified. Reinforcement favoring reproductive isolation

2880-469: Is required for both parapatric and sympatric speciation. Without reinforcement, the geographic area of contact between different forms of the same species, called their "hybrid zone", will not develop into a boundary between the different species. Hybrid zones are regions where diverged populations meet and interbreed. Hybrid offspring are common in these regions, which are usually created by diverged species coming into secondary contact . Without reinforcement,

2976-503: Is set in Victorian England and follows an inventor who constructs a machine that enables him to travel into the distant future. Once there, he discovers that mankind's descendants have divided into two species , the passive, childlike, and vegetarian Eloi and the underground-dwelling Morlocks, who feed on the Eloi. The film was originally released on August 17, 1960, and was distributed by Metro-Goldwyn-Mayer . It received

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3072-492: Is stronger between D. portschinskii and D. rudis , which separated earlier but live in similar habitats than between D. valentini and two other species, which separated later but live in climatically different habitats. Ecologists refer to parapatric and peripatric speciation in terms of ecological niches . A niche must be available in order for a new species to be successful. Ring species such as Larus gulls have been claimed to illustrate speciation in progress, though

3168-409: Is that if the parents of the hybrid offspring each have naturally selected traits for their own certain environments, the hybrid offspring will bear traits from both, therefore would not fit either ecological niche as well as either parent (ecological speciation). The low fitness of the hybrids would cause selection to favor assortative mating , which would control hybridization. This is sometimes called

3264-487: Is the evolutionary process by which populations evolve to become distinct species . The biologist Orator F. Cook coined the term in 1906 for cladogenesis , the splitting of lineages, as opposed to anagenesis , phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book On the Origin of Species . He also identified sexual selection as

3360-449: Is the choice of mates severely restricted but population bottlenecks, founder effects, genetic drift and inbreeding cause rapid, random changes in the isolated population's genetic composition. Furthermore, hybridization with a related species trapped in the same isolate might introduce additional genetic changes. If an isolated population such as this survives its genetic upheavals , and subsequently expands into an unoccupied niche, or into

3456-409: Is the fourth dimension. He shows David Filby, Dr. Philip Hillyer, Anthony Bridewell, and Walter Kemp a scale model time machine. When a tiny lever on it is pressed, the device quickly disappears. George says it went forward in time, but his friends are skeptical. The group leaves George's house, Filby reluctantly, as he senses George is not himself. George then retires to his private laboratory that holds

3552-581: Is thought to have arisen from hybrid speciation. Hybridization is an important means of speciation in plants, since polyploidy (having more than two copies of each chromosome ) is tolerated in plants more readily than in animals. Polyploidy is important in hybrids as it allows reproduction, with the two different sets of chromosomes each being able to pair with an identical partner during meiosis. Polyploids also have more genetic diversity, which allows them to avoid inbreeding depression in small populations. Hybridization without change in chromosome number

3648-570: The Academy Award for Best Special Effects for its time-lapse photographic effects, which show the world changing rapidly as the time traveler journeys into the future. On January 5, 1900, four friends arrive for a dinner at the London home of their inventor friend George. He is absent, then suddenly appears, bedraggled and exhausted. He recounts what happened to him. At the group's earlier dinner on New Year's Eve , George stated that time

3744-620: The Bateson-Dobzhansky-Muller model . Genes from allopatric populations will have different evolutionary backgrounds and are never tested together until hybridization at secondary contact, when negative epistatic interactions will be exposed. In other words, new alleles will emerge in a population and only pass through selection if they work well together with other genes in the same population, but it may not be compatible with genes in an allopatric population, be those other newly derived alleles or retained ancestral alleles. This

3840-444: The heterozygote leads to selection for behaviours or mechanisms that prevent their interbreeding . Parapatric speciation is modelled on continuous variation within a "single", connected habitat acting as a source of natural selection rather than the effects of isolation of habitats produced in peripatric and allopatric speciation. Parapatric speciation may be associated with differential landscape-dependent selection . Even if there

3936-442: The relatedness and age of populations and species . ) This argument implies that evolution can only occur if mutant mates cannot be avoided, as a result of a severe scarcity of potential mates. This is most likely to occur in small, isolated communities . These occur most commonly on small islands, in remote valleys, lakes, river systems, or caves, or during the aftermath of a mass extinction . Under these circumstances, not only

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4032-476: The Bayonet and Bernie Boston 's Pulitzer Prize–nominated photograph Flower Power , popularized the association of flowers with the counterculture movement of the 1970s. Hippies embraced the symbolism by dressing in clothing with embroidered flowers and vibrant colors, wearing flowers in their hair, and distributing flowers to the public, becoming known as flower children. John Phillips of The Mamas &

4128-581: The Papas wrote the song " San Francisco (Be Sure to Wear Flowers in Your Hair) " for his friend Scott McKenzie to promote the Monterey Pop Festival that Phillips was helping to organize. Released on May 13, 1967, the song's lyrics urged visitors to San Francisco to "wear some flowers in your hair", in keeping with the festival's billing as "three days of music, love, and flowers". The song

4224-498: The Wallace effect after the evolutionary biologist Alfred Russel Wallace who suggested in the late 19th century that it might be an important factor in speciation. Conversely, if the hybrid offspring are more fit than their ancestors, then the populations will merge back into the same species within the area they are in contact. Another important theoretical mechanism is the arise of intrinsic genetic incompatibilities, addressed in

4320-581: The adult members of a sexual species has stimulated the proliferation of field guides on birds, mammals, reptiles, insects, and many other taxa , in which a species can be described with a single illustration (or two, in the case of sexual dimorphism ). Once a population has become as homogeneous in appearance as is typical of most species (and is illustrated in the photograph of the African pygmy kingfisher), its members will avoid mating with members of other populations that look different from themselves. Thus,

4416-468: The atmosphere. Another ring describes humanity's struggle for survival; many people lived underground , while some eventually returned to the surface. George realizes this was the beginning of the speciation that resulted in the Morlocks and Eloi. He starts to climb down a shaft, but stops when sirens emerge and blare from the sphinx. The Eloi go into a trance-like state and head for the opened doors at

4512-626: The avoidance of mates displaying rare and unusual phenotypic features inevitably leads to reproductive isolation, one of the hallmarks of speciation. In the contrasting case of organisms that reproduce asexually , there is no cost of rarity; consequently, there are only benefits to fine-scale adaptation. Thus, asexual organisms very frequently show the continuous variation in form (often in many different directions) that Darwin expected evolution to produce, making their classification into "species" (more correctly, morphospecies ) very difficult. All forms of natural speciation have taken place over

4608-416: The birds now known as Darwin's finches to be a classic case of adaptive evolutionary radiation. In peripatric speciation, a subform of allopatric speciation, new species are formed in isolated, smaller peripheral populations that are prevented from exchanging genes with the main population. It is related to the concept of a founder effect , since small populations often undergo bottlenecks . Genetic drift

4704-442: The budding off of a new species from a parent species, both driven by a biological "fashion fad" (a preference for a feature, or features, in one or both sexes, that do not necessarily have any adaptive qualities). In the second sense, "speciation" refers to the wide-spread tendency of sexual creatures to be grouped into clearly defined species, rather than forming a continuum of phenotypes both in time and space – which would be

4800-437: The character a more athletic, idealistic dimension. It was Taylor's first lead role in a feature film. Mimieux was cast in the role of Weena despite having no previous acting experience. During a screen test, director George Pal observed an innocent persona she portrayed, yet despite being his first choice, she was turned down by MGM. Following Pal's insistence and despite Taylor's preferred choice being Shirley Knight , Mimieux

4896-508: The closed sphinx. Weena, who stays with him, says that Morlocks are responsible, noting they only come out at night. A hideous-looking Morlock jumps out and tries to drag Weena away, but is warded off by George's lit torch. The next day, Weena shows George truncated cone structures dotting the landscape, air shafts that lead down to the Morlocks' caverns. Weena also shows George an ancient museum where "talking rings" tell of long-ago war between East and West that lasted 326 years and contaminated

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4992-613: The costumes and set were re-used from Forbidden Planet (1956), such as the Civil Defence air raid officer uniform, which was the C-57-D crew uniform, and the large acrylic sphere in the talking rings room, a prop from the C-57-D's control bridge. In scenes where lava is shown to overrun the streets of London onto a miniature replica set, oatmeal was used as a substitute. The oatmeal had been prepared several days prior and left over

5088-549: The course of evolution ; however, debate persists as to the relative importance of each mechanism in driving biodiversity . One example of natural speciation is the diversity of the three-spined stickleback , a marine fish that, after the last glacial period , has undergone speciation into new freshwater colonies in isolated lakes and streams. Over an estimated 10,000 generations, the sticklebacks show structural differences that are greater than those seen between different genera of fish including variations in fins, changes in

5184-416: The crust of the earth". That clearly defined species actually do exist in nature in both space and time implies that some fundamental feature of natural selection operates to generate and maintain species. It has been argued that the resolution of Darwin's first dilemma lies in the fact that out-crossing sexual reproduction has an intrinsic cost of rarity. The cost of rarity arises as follows. If, on

5280-468: The current, screams for help. When her indifferent companions do nothing, George rescues her. She is named Weena and her people are the Eloi ; they do not operate machines, work, or read, and know little of their history. Their food is always provided for them. One young man shows George a library, but the books crumble to dust when touched. Outraged, he decides to leave, but his machine has been dragged inside

5376-431: The dates and methods of the initiation of such species are not clear. Often, the domestic counterpart can still interbreed and produce fertile offspring with its wild ancestor. This is the case with domestic cattle , which can be considered the same species as several varieties of wild ox , gaur , and yak ; and with domestic sheep that can interbreed with the mouflon . The best-documented creations of new species in

5472-459: The evidence, "...accumulated from top-down studies of adaptation and reproductive isolation". Sexual selection can drive speciation in a clade, independently of natural selection . However the term "speciation", in this context, tends to be used in two different, but not mutually exclusive senses. The first and most commonly used sense refers to the "birth" of new species. That is, the splitting of an existing species into two separate species, or

5568-438: The existing plant and most animal species have undergone an event of polyploidization in their evolutionary history. Reproduction of successful polyploid species is sometimes asexual, by parthenogenesis or apomixis , as for unknown reasons many asexual organisms are polyploid. Rare instances of polyploid mammals are known, but most often result in prenatal death. Hybridization between two different species sometimes leads to

5664-418: The expense of one or other of its neighboring species, if the environment is saturated), this will immediately make it easier for its members to find sexual partners. The members of the neighboring species, whose population sizes have decreased, experience greater difficulty in finding mates, and therefore form pairs less frequently than the larger species. This has a snowball effect, with large species growing at

5760-489: The expense of the smaller, rarer species, eventually driving them to extinction . Eventually, only a few species remain, each distinctly different from the other. Rarity not only imposes the risk of failure to find a mate, but it may also incur indirect costs, such as the resources expended or risks taken to seek out a partner at low population densities. Rarity brings with it other costs. Rare and unusual features are very seldom advantageous. In most instances, they indicate

5856-467: The expression of advantageous recessive phenotypes, reducing the recombination load, and reducing the cost of sex. The hawthorn fly ( Rhagoletis pomonella ), also known as the apple maggot fly, appears to be undergoing sympatric speciation. Different populations of hawthorn fly feed on different fruits. A distinct population emerged in North America in the 19th century some time after apples ,

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5952-434: The extent that Pal requested that some of her earlier scenes be reshot to take advantage of her improved acting ability. The time machine prop was designed by MGM art director Bill Ferrari and built by Wah Chang . Recognized today as an iconic film property , Ferrari's machine suggested a sled made up of a large clockwork rotating disk. The disk rotated at various speeds to indicate movement through time, evoking both

6048-526: The external appearance of their carriers will then rarely be passed on to the next and subsequent generations. They would therefore seldom be tested by natural selection. Evolution is, therefore, effectively halted or slowed down considerably. The only mutations that can accumulate in a population, on this punctuated equilibrium view, are ones that have no noticeable effect on the outward appearance and functionality of their bearers (i.e., they are "silent" or " neutral mutations ", which can be, and are, used to trace

6144-421: The extraordinary diversity of crustaceans living in the depths of Siberia's Lake Baikal . Budding speciation has been proposed as a particular form of sympatric speciation, whereby small groups of individuals become progressively more isolated from the ancestral stock by breeding preferentially with one another. This type of speciation would be driven by the conjunction of various advantages of inbreeding such as

6240-431: The far distant future. Harrison's Reports called the film "an excellent science-fiction melodrama ... jammed full of suspense, action and out-of-this-world special effects", although the review lamented a lack of comic relief. Whitney Balliett of The New Yorker wrote in a negative review that the film "converts this good simple-minded material into bad simple-minded material", by including such Hollywood touches as

6336-600: The film earned $ 1,610,000 in the United States and Canada and $ 1 million elsewhere, turning a profit of $ 245,000. The film had admissions of 363,915 in France. Kine Weekly called it a "money maker" at the British box office in 1960. Gene Warren and Tim Baar won the 1961 Academy Award for Best Effects, Special Effects . The film was nominated for the 1961 Hugo Award for Best Dramatic Presentation . In 1993,

6432-472: The film holds a score of 76% based on 38 reviews, with an average rating of 7.0/10. The website's critics consensus reads, "Its campy flourishes tend to subdue its dramatic stakes, but The Time Machine brings H.G. Wells' story to life with plenty of sci-fi charm and a colorful sense of visual design." On Metacritic , the film has a weighted average score of 67 out of 100 based on nine critics, indicating "generally favorable reviews". According to MGM records,

6528-447: The film was "at its best in the scenes where George explores his new surroundings at each time stop", but found the acting "inadequate: Rod Taylor lacks both intellect and period sense, belonging more to an American science fiction world, and Weena is just a doll. Nevertheless, Pal's visual flair and genuine feeling for his fantasy world help to maintain an entertaining surface for most of the time". On review aggregator Rotten Tomatoes ,

6624-473: The film's main character (alluded to in dialogue only as "George") connects him both with George Pal and with the story's original science fiction writer H. G. (George) Wells. The name "H. George Wells" can be seen on a brass plaque on the time machine. The film was created on a tight budget and given a filming schedule of just 29 days. Taylor was already Pal's first choice to play the time traveller, after having lunch together numerous times where they discussed

6720-627: The first aspect, and it is now widely agreed that the critical factor behind the origin of new species is reproductive isolation. In On the Origin of Species (1859), Darwin interpreted biological evolution in terms of natural selection, but was perplexed by the clustering of organisms into species. Chapter 6 of Darwin's book is entitled "Difficulties of the Theory". In discussing these "difficulties" he noted Firstly, why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms? Why

6816-417: The future is vanishingly small. Therefore, while a species or group might benefit from being able to adapt to a new environment by accumulating a wide range of genetic variation, this is to the detriment of the individuals who have to carry these mutations until a small, unpredictable minority of them ultimately contributes to such an adaptation. Thus, the capability to evolve would require group selection ,

6912-420: The laboratory were performed in the late 1980s. William R. Rice and George W. Salt bred Drosophila melanogaster fruit flies using a maze with three different choices of habitat such as light/dark and wet/dry. Each generation was placed into the maze, and the groups of flies that came out of two of the eight exits were set apart to breed with each other in their respective groups. After thirty-five generations,

7008-434: The moods of hostile weakness, friendly strength and hostile strength. The Time Machine (1960 film) The Time Machine (also marketed as H. G. Wells' The Time Machine ) is a 1960 American period post-apocalyptic science fiction film based on the 1895 novella of the same name by H. G. Wells . It was produced and directed by George Pal , and stars Rod Taylor , Yvette Mimieux , and Alan Young . The story

7104-526: The more obvious or logical consequence of natural selection. This was indeed recognized by Darwin as problematic, and included in his On the Origin of Species (1859), under the heading "Difficulties with the Theory". There are several suggestions as to how mate choice might play a significant role in resolving Darwin's dilemma . If speciation takes place in the absence of natural selection, it might be referred to as nonecological speciation . New species have been created by animal husbandry , but

7200-527: The number or size of their bony plates, variable jaw structure, and color differences. During allopatric (from the ancient Greek allos , "other" + patrā , "fatherland") speciation, a population splits into two geographically isolated populations (for example, by habitat fragmentation due to geographical change such as mountain formation ). The isolated populations then undergo genotypic or phenotypic divergence as: (a) they become subjected to dissimilar selective pressures; (b) different mutations arise in

7296-429: The project. Taylor admitted being fascinated with Pal's rough drawings detailing various scenes. In a 1986 interview, he commented how he had been asked more questions about his role in this film than any other across his career. Pal originally considered casting a middle-aged British actor like David Niven or James Mason as George. He later changed his mind and selected the younger Australian actor Rod Taylor to give

7392-455: The question of why the long term rate of evolution is far slower than is theoretically possible. Evolution is imposed on species or groups. It is not planned or striven for in some Lamarckist way. The mutations on which the process depends are random events, and, except for the " silent mutations " which do not affect the functionality or appearance of the carrier, are thus usually disadvantageous, and their chance of proving to be useful in

7488-405: The result is progeny which are immediately reproductively isolated from the parent population. New species can also be created through hybridization , followed by reproductive isolation, if the hybrid is favoured by natural selection. In addressing the origin of species, there are two key issues: Since Charles Darwin's time, efforts to understand the nature of species have primarily focused on

7584-695: The same area. The best known example of sympatric speciation is that of the cichlids of East Africa inhabiting the Rift Valley lakes , particularly Lake Victoria , Lake Malawi and Lake Tanganyika . There are over 800 described species, and according to estimates, there could be well over 1,600 species in the region. Their evolution is cited as an example of both natural and sexual selection . A 2008 study suggests that sympatric speciation has occurred in Tennessee cave salamanders . Sympatric speciation driven by ecological factors may also account for

7680-429: The shafts. The resulting fires cause the caverns to burn, then collapse. The next morning, the sphinx's doors are open. George sees his time machine inside. When he enters the sphinx, the doors close and George is attacked by Morlocks. He escapes in his machine and returns to 1900. After George recounts his story, his friends remain skeptical. He produces a flower Weena gave him, and Filby, an amateur botanist , says it

7776-412: The situation may be more complex. The grass Anthoxanthum odoratum may be starting parapatric speciation in areas of mine contamination. Sympatric speciation is the formation of two or more descendant species from a single ancestral species all occupying the same geographic location. Often-cited examples of sympatric speciation are found in insects that become dependent on different host plants in

7872-433: The sphinx's base. The sirens stop and the doors close, trapping Weena and others inside, while those outside merely walk away. George enters the caverns through the air shafts. He discovers that the Morlocks raise the Eloi as food. He finds Weena and fights off the creatures, finally inspiring the Eloi to defend themselves. George sets fires and urges the Eloi to climb to the surface. He directs them to drop tree branches down

7968-543: The summer, taking with them new styles, ideas, and behaviors and introducing them in all major cities of the U.S. and western Europe. In his book, Prometheus Rising , the philosopher Robert Anton Wilson suggested that the flower children could be viewed in Jungian terms as a collective social symbol representing the mood of friendly weakness. In 1995, The Sekhmet Hypothesis extended Wilson's idea into other pop cultural trends with other youth movements being compared to

8064-443: The time axis, whose lengths depict how long each of them existed. The fact that the lines remain parallel with the time axis illustrates the unchanging appearance of each of the fossil species depicted on the graph. During each species' existence new species appear at random intervals, each also lasting many hundreds of thousands of years before disappearing without a change in appearance. The exact relatedness of these concurrent species

8160-494: The time in the world". George Pal was already known for his pioneering work with stop-motion animation , having been nominated almost yearly for an Oscar during the 1940s. In 1958, Pal was approached by Shiro Kido to co-produce a Japanese adaptation of the novel with Shochiku Productions . After Kido left the project and Pal was unable to sell Hollywood on the concept of the film, he found MGM's British studio (where he had filmed Tom Thumb ) open to his proposal. The name of

8256-535: The traits that directly or indirectly bring about the evolution of reproductive isolation". Evidence for the role ecology plays in the process of speciation exists. Studies of stickleback populations support ecologically-linked speciation arising as a by-product, alongside numerous studies of parallel speciation, where isolation evolves between independent populations of species adapting to contrasting environments than between independent populations adapting to similar environments. Ecological speciation occurs with much of

8352-774: The two groups and their offspring were isolated reproductively because of their strong habitat preferences: they mated only within the areas they preferred, and so did not mate with flies that preferred the other areas. The history of such attempts is described by Rice and Elen E. Hostert (1993). Diane Dodd used a laboratory experiment to show how reproductive isolation can develop in Drosophila pseudoobscura fruit flies after several generations by placing them in different media, starch- and maltose-based media. [REDACTED] Dodd's experiment has been replicated many times, including with other kinds of fruit flies and foods. Such rapid evolution of reproductive isolation may sometimes be

8448-668: The two populations. When the populations come back into contact, they have evolved such that they are reproductively isolated and are no longer capable of exchanging genes . Island genetics is the term associated with the tendency of small, isolated genetic pools to produce unusual traits. Examples include insular dwarfism and the radical changes among certain famous island chains, for example on Komodo . The Galápagos Islands are particularly famous for their influence on Charles Darwin. During his five weeks there he heard that Galápagos tortoises could be identified by island, and noticed that finches differed from one island to another, but it

8544-503: The two species would have uncontrollable inbreeding . Reinforcement may be induced in artificial selection experiments as described below. Ecological selection is "the interaction of individuals with their environment during resource acquisition". Natural selection is inherently involved in the process of speciation, whereby, "under ecological speciation, populations in different environments, or populations exploiting different resources, experience contrasting natural selection pressures on

8640-507: The world flocked to San Francisco's Haight-Ashbury district, Berkeley , and other Bay Area cities during the Summer of Love in search of different value systems and experiences. After the Monterey Pop Festival in June of 1967, the Summer of Love became a watershed event in the development of a worldwide 1960s counterculture when newly recruited flower children returned home at the end of

8736-539: Was a popular hit, reaching number 4 on the music chart in the United States and number 1 in the United Kingdom and most of Europe, and became an unofficial anthem for hippies, flower power and the flower child concept. After the January 14, 1967 Human Be-In organized by artist Michael Bowen (among other things, announcements told participants to bring flowers), as many as 100,000 young people from all over

8832-470: Was asked back for another screen test where she was offered the part. Taylor observed her inability to act, describing how he thought she was like "kind of a strange hippie child" and was concerned that her lack of experience meant she would be difficult to act alongside. Mimieux lied about her age to Pal, stating she was 18 despite being only 17 when filming began. Having initially struggled on set, Mimieux gradually improved as her confidence in acting grew, to

8928-463: Was complete, then they will have already developed into two separate incompatible species. If their reproductive isolation is incomplete, then further mating between the populations will produce hybrids, which may or may not be fertile. If the hybrids are infertile, or fertile but less fit than their ancestors, then there will be further reproductive isolation and speciation has essentially occurred, as in horses and donkeys . One reasoning behind this

9024-413: Was only nine months later that he speculated that such facts could show that species were changeable. When he returned to England , his speculation on evolution deepened after experts informed him that these were separate species, not just varieties, and famously that other differing Galápagos birds were all species of finches. Though the finches were less important for Darwin, more recent research has shown

9120-452: Was released in 1987 produced by Arnold Leibovit , the original soundtrack recording was composed and conducted by Russell Garcia himself and released by GNP Crescendo. Arnold Leibovit Entertainment produced and re-released a new updated stereo digital remaster in 2022 with expanded tracks and uncut as composer Garcia originally wrote it. Included is a 20-page collector's booklet with an exclusive interview with Garcia. [ [1] ] The track listing

9216-786: Was shown to occur in nature so often that geneticists largely dismissed the moving gene hypothesis. However, 2006 research shows that jumping of a gene from one chromosome to another can contribute to the birth of new species. This validates the reproductive isolation mechanism, a key component of speciation. There is debate as to the rate at which speciation events occur over geologic time. While some evolutionary biologists claim that speciation events have remained relatively constant and gradual over time (known as "Phyletic gradualism" – see diagram), some palaeontologists such as Niles Eldredge and Stephen Jay Gould have argued that species usually remain unchanged over long stretches of time, and that speciation occurs only over relatively brief intervals,

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