Ateisters syn på intelligensen til religiøse

[wingeer]

Ja, det var det jeg sa. At det en teori som ikke er bevist. Har jeg sagt noe annet enn min subjektive mening?. Nei. God natt

Subjektive meninger har ingenting med vitenskap å gjøre. Evolusjon er en teori som ikke kan bevises, på lik linje med gravitasjon. Det kan derimot fremlegges indisier, hvilket det har vært flere av. Om du forventer å få bevis, kan du egentlig bare gå å legge deg.

 

Ateister/Agnostikere har en IQ som er i gjennomsnitt høyere enn dem som er religiøse. Dette betyr ikke at folk som er religiøse ikke kan være smarte også.

 

Forøvrig synes jeg IQ-konseptet er en veldig begrenset måte å se på menneskesinnet på, men det får diskuteres en annen gang, et annet sted.

Vel. Det er tre typer løgn: hvit, sort og statistikk. Hvor har du tallene dine fra?

 

Det er det.

[Rudde]

Jeg er Ateist og tror/mener religiøse folk har mangel på kritisk (og delvis logisk) tenking. Jeg vil ikke kalle dem alle dumme, det blir litt overdrevet da det finnes veldig mange smarte religiøse folk, kanskje de poser som religiøs for god PR (i steder i USA, hvor ateister er veldig hatet) eller for å ikke skuffe foreldre, eller de er oppdratt kristen (f.eks.) og ingen har faktisk spurt om de tror på gud, alle bare antar de gjør det.

[kris98]

Hvordan er statistikk løgn? Det er da helt objektive tall det er prat om.

 

"Of 43 studies carried out since 1927 on the relationship between religious belief and one's intelligence and/or educational level, all but four found an inverse connection. That is, the higher one's intelligence or education level, the less one is likely to be religious or hold "beliefs" of any kind."

Bell, Paul. "Would you believe it?" Mensa Magazine, Feb. 2002, pp. 12–13

[wingeer]

Statistikk per se er ikke løgn. Dog er det lett å lyve med statistikk.

[mrDave]

Det er feil, den eneste evulsjonen som er bevist er et kamskjell som har utviklet seg gjennom noen millioner år. Resten er bare dyr de har funnet som ligner på hverandre. Frykter at du er et resultat av det elendige skoleverket vårt med en tullete subjektiv mening.

Har du AIDS, eller?

 

Du fortalte nettopp hele forumet at "vel, evolusjon skjedde akkurat der, MEN IKKE ELLERS NEINEINEI HUFFAMEI!". Og ja, det er nok skoleverket som er skyld i hva jeg tror. Heller det fremfor den lokale kirken min.

 

Nei. Det de fant ut om kamskjellet var at utviklingen var sy utrolig liten at det ville ikke ha noe å si hvis man ganget opp årene til 6 milliarder, så ville det fortsatt være helt ubetydelig.

[bazxlckjv aeoif34wedjifoxj]

Skal jeg tro på den tilfeldige forumbrukeren mrDave og noen skrullete kreasjonistvenner eller hele verdens seriøse vitenskapsstand... Hmmmmmmmmmmmmmmmmmmmmmm.... vanskelig valg her. Må nok gå i tenkeboksen på denne.

[kris98]

Nei. Det de fant ut om kamskjellet var at utviklingen var sy utrolig liten at det ville ikke ha noe å si hvis man ganget opp årene til 6 milliarder, så ville det fortsatt være helt ubetydelig.

Evolusjon er evolusjon, uansett hvordan du ser på det.

[mrDave]

Nei. Det de fant ut om kamskjellet var at utviklingen var sy utrolig liten at det ville ikke ha noe å si hvis man ganget opp årene til 6 milliarder, så ville det fortsatt være helt ubetydelig.

Evolusjon er evolusjon, uansett hvordan du ser på det.

 

Jepp, mikroevolusjon

[kris98]

Makroevolusjon er mikroevolusjon på en større skala. Du får ikke den ene uten den andre.

[Thitorkin]

http://www.talkorigins.org/faqs/faq-speciation.html#part3

 

Eg forventer at de som svarer leser alt dette.

 

 

 

"5.0 Observed Instances of Speciation

 

The following are several examples of observations of speciation.

5.1 Speciations Involving Polyploidy, Hybridization or Hybridization Followed by Polyploidization.

 

5.1.1 Plants

 

(See also the discussion in de Wet 1971).

5.1.1.1 Evening Primrose (Oenothera gigas)

 

While studying the genetics of the evening primrose, Oenothera lamarckiana, de Vries (1905) found an unusual variant among his plants. O. lamarckiana has a chromosome number of 2N = 14. The variant had a chromosome number of 2N = 28. He found that he was unable to breed this variant with O. lamarckiana. He named this new species O. gigas.

5.1.1.2 Kew Primrose (Primula kewensis)

 

Digby (1912) crossed the primrose species Primula verticillata and P. floribunda to produce a sterile hybrid. Polyploidization occurred in a few of these plants to produce fertile offspring. The new species was named P. kewensis. Newton and Pellew (1929) note that spontaneous hybrids of P. verticillata and P. floribunda set tetraploid seed on at least three occasions. These happened in 1905, 1923 and 1926.

5.1.1.3 Tragopogon

 

Owenby (1950) demonstrated that two species in this genus were produced by polyploidization from hybrids. He showed that Tragopogon miscellus found in a colony in Moscow, Idaho was produced by hybridization of T. dubius and T. pratensis. He also showed that T. mirus found in a colony near Pullman, Washington was produced by hybridization of T. dubius and T. porrifolius. Evidence from chloroplast DNA suggests that T. mirus has originated independently by hybridization in eastern Washington and western Idaho at least three times (Soltis and Soltis 1989). The same study also shows multiple origins for T. micellus.

5.1.1.4 Raphanobrassica

 

The Russian cytologist Karpchenko (1927, 1928) crossed the radish, Raphanus sativus, with the cabbage, Brassica oleracea. Despite the fact that the plants were in different genera, he got a sterile hybrid. Some unreduced gametes were formed in the hybrids. This allowed for the production of seed. Plants grown from the seeds were interfertile with each other. They were not interfertile with either parental species. Unfortunately the new plant (genus Raphanobrassica) had the foliage of a radish and the root of a cabbage.

5.1.1.5 Hemp Nettle (Galeopsis tetrahit)

 

A species of hemp nettle, Galeopsis tetrahit, was hypothesized to be the result of a natural hybridization of two other species, G. pubescens and G. speciosa (Muntzing 1932). The two species were crossed. The hybrids matched G. tetrahit in both visible features and chromosome morphology.

5.1.1.6 Madia citrigracilis

 

Along similar lines, Clausen et al. (1945) hypothesized that Madia citrigracilis was a hexaploid hybrid of M. gracilis and M. citriodora As evidence they noted that the species have gametic chromosome numbers of n = 24, 16 and 8 respectively. Crossing M. gracilis and M. citriodora resulted in a highly sterile triploid with n = 24. The chromosomes formed almost no bivalents during meiosis. Artificially doubling the chromosome number using colchecine produced a hexaploid hybrid which closely resembled M. citrigracilis and was fertile.

5.1.1.7 Brassica

 

Frandsen (1943, 1947) was able to do this same sort of recreation of species in the genus Brassica (cabbage, etc.). His experiments showed that B. carinata (n = 17) may be recreated by hybridizing B. nigra (n = 8) and B. oleracea, B. juncea (n = 18) may be recreated by hybridizing B. nigra and B. campestris (n = 10), and B. napus (n = 19) may be recreated by hybridizing B. oleracea and B. campestris.

5.1.1.8 Maidenhair Fern (Adiantum pedatum)

 

Rabe and Haufler (1992) found a naturally occurring diploid sporophyte of maidenhair fern which produced unreduced (2N) spores. These spores resulted from a failure of the paired chromosomes to dissociate during the first division of meiosis. The spores germinated normally and grew into diploid gametophytes. These did not appear to produce antheridia. Nonetheless, a subsequent generation of tetraploid sporophytes was produced. When grown in the lab, the tetraploid sporophytes appear to be less vigorous than the normal diploid sporophytes. The 4N individuals were found near Baldwin City, Kansas.

5.1.1.9 Woodsia Fern (Woodsia abbeae)

 

Woodsia abbeae was described as a hybrid of W. cathcariana and W. ilvensis (Butters 1941). Plants of this hybrid normally produce abortive sporangia containing inviable spores. In 1944 Butters found a W. abbeae plant near Grand Portage, Minn. that had one fertile frond (Butters and Tryon 1948). The apical portion of this frond had fertile sporangia. Spores from this frond germinated and grew into prothallia. About six months after germination sporophytes were produced. They survived for about one year. Based on cytological evidence, Butters and Tryon concluded that the frond that produced the viable spores had gone tetraploid. They made no statement as to whether the sporophytes grown produced viable spores.

5.1.2 Animals

 

Speciation through hybridization and/or polyploidy has long been considered much less important in animals than in plants [[[refs.]]]. A number of reviews suggest that this view may be mistaken. (Lokki and Saura 1980; Bullini and Nascetti 1990; Vrijenhoek 1994). Bullini and Nasceti (1990) review chromosomal and genetic evidence that suggest that speciation through hybridization may occur in a number of insect species, including walking sticks, grasshoppers, blackflies and cucurlionid beetles. Lokki and Saura (1980) discuss the role of polyploidy in insect evolution. Vrijenhoek (1994) reviews the literature on parthenogenesis and hybridogenesis in fish. I will tackle this topic in greater depth in the next version of this document.

5.2 Speciations in Plant Species not Involving Hybridization or Polyploidy

 

5.2.1 Stephanomeira malheurensis

 

Gottlieb (1973) documented the speciation of Stephanomeira malheurensis. He found a single small population (< 250 plants) among a much larger population (> 25,000 plants) of S. exigua in Harney Co., Oregon. Both species are diploid and have the same number of chromosomes (N = 8). S. exigua is an obligate outcrosser exhibiting sporophytic self-incompatibility. S. malheurensis exhibits no self-incompatibility and self-pollinates. Though the two species look very similar, Gottlieb was able to document morphological differences in five characters plus chromosomal differences. F1 hybrids between the species produces only 50% of the seeds and 24% of the pollen that conspecific crosses produced. F2 hybrids showed various developmental abnormalities.

5.2.2 Maize (Zea mays)

 

Pasterniani (1969) produced almost complete reproductive isolation between two varieties of maize. The varieties were distinguishable by seed color, white versus yellow. Other genetic markers allowed him to identify hybrids. The two varieties were planted in a common field. Any plant's nearest neighbors were always plants of the other strain. Selection was applied against hybridization by using only those ears of corn that showed a low degree of hybridization as the source of the next years seed. Only parental type kernels from these ears were planted. The strength of selection was increased each year. In the first year, only ears with less than 30% intercrossed seed were used. In the fifth year, only ears with less than 1% intercrossed seed were used. After five years the average percentage of intercrossed matings dropped from 35.8% to 4.9% in the white strain and from 46.7% to 3.4% in the yellow strain.

5.2.3 Speciation as a Result of Selection for Tolerance to a Toxin: Yellow Monkey Flower (Mimulus guttatus)

 

At reasonably low concentrations, copper is toxic to many plant species. Several plants have been seen to develop a tolerance to this metal (Macnair 1981). Macnair and Christie (1983) used this to examine the genetic basis of a postmating isolating mechanism in yellow monkey flower. When they crossed plants from the copper tolerant "Copperopolis" population with plants from the nontolerant "Cerig" population, they found that many of the hybrids were inviable. During early growth, just after the four leaf stage, the leaves of many of the hybrids turned yellow and became necrotic. Death followed this. This was seen only in hybrids between the two populations. Through mapping studies, the authors were able to show that the copper tolerance gene and the gene responsible for hybrid inviability were either the same gene or were very tightly linked. These results suggest that reproductive isolation may require changes in only a small number of genes.

5.3 The Fruit Fly Literature

 

5.3.1 Drosophila paulistorum

 

Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).

5.3.2 Disruptive Selection on Drosophila melanogaster

 

Thoday and Gibson (1962) established a population of Drosophila melanogaster from four gravid females. They applied selection on this population for flies with the highest and lowest numbers of sternoplural chaetae (hairs). In each generation, eight flies with high numbers of chaetae were allowed to interbreed and eight flies with low numbers of chaetae were allowed to interbreed. Periodically they performed mate choice experiments on the two lines. They found that they had produced a high degree of positive assortative mating between the two groups. In the decade or so following this, eighteen labs attempted unsuccessfully to reproduce these results. References are given in Thoday and Gibson 1970.

5.3.3 Selection on Courtship Behavior in Drosophila melanogaster

 

Crossley (1974) was able to produce changes in mating behavior in two mutant strains of D. melanogaster. Four treatments were used. In each treatment, 55 virgin males and 55 virgin females of both ebony body mutant flies and vestigial wing mutant flies (220 flies total) were put into a jar and allowed to mate for 20 hours. The females were collected and each was put into a separate vial. The phenotypes of the offspring were recorded. Wild type offspring were hybrids between the mutants. In two of the four treatments, mating was carried out in the light. In one of these treatments all hybrid offspring were destroyed. This was repeated for 40 generations. Mating was carried out in the dark in the other two treatments. Again, in one of these all hybrids were destroyed. This was repeated for 49 generations. Crossley ran mate choice tests and observed mating behavior. Positive assortative mating was found in the treatment which had mated in the light and had been subject to strong selection against hybridization. The basis of this was changes in the courtship behaviors of both sexes. Similar experiments, without observation of mating behavior, were performed by Knight, et al. (1956).

5.3.4 Sexual Isolation as a Byproduct of Adaptation to Environmental Conditions in Drosophila melanogaster

 

Kilias, et al. (1980) exposed D. melanogaster populations to different temperature and humidity regimes for several years. They performed mating tests to check for reproductive isolation. They found some sterility in crosses among populations raised under different conditions. They also showed some positive assortative mating. These things were not observed in populations which were separated but raised under the same conditions. They concluded that sexual isolation was produced as a byproduct of selection.

5.3.5 Sympatric Speciation in Drosophila melanogaster

 

In a series of papers (Rice 1985, Rice and Salt 1988 and Rice and Salt 1990) Rice and Salt presented experimental evidence for the possibility of sympatric speciation. They started from the premise that whenever organisms sort themselves into the environment first and then mate locally, individuals with the same habitat preferences will necessarily mate assortatively. They established a stock population of D. melanogaster with flies collected in an orchard near Davis, California. Pupae from the culture were placed into a habitat maze. Newly emerged flies had to negotiate the maze to find food. The maze simulated several environmental gradients simultaneously. The flies had to make three choices of which way to go. The first was between light and dark (phototaxis). The second was between up and down (geotaxis). The last was between the scent of acetaldehyde and the scent of ethanol (chemotaxis). This divided the flies among eight habitats. The flies were further divided by the time of day of emergence. In total the flies were divided among 24 spatio-temporal habitats.

 

They next cultured two strains of flies that had chosen opposite habitats. One strain emerged early, flew upward and was attracted to dark and acetaldehyde. The other emerged late, flew downward and was attracted to light and ethanol. Pupae from these two strains were placed together in the maze. They were allowed to mate at the food site and were collected. Eye color differences between the strains allowed Rice and Salt to distinguish between the two strains. A selective penalty was imposed on flies that switched habitats. Females that switched habitats were destroyed. None of their gametes passed into the next generation. Males that switched habitats received no penalty. After 25 generations of this mating tests showed reproductive isolation between the two strains. Habitat specialization was also produced.

 

They next repeated the experiment without the penalty against habitat switching. The result was the same -- reproductive isolation was produced. They argued that a switching penalty is not necessary to produce reproductive isolation. Their results, they stated, show the possibility of sympatric speciation.

5.3.6 Isolation Produced as an Incidental Effect of Selection on several Drosophila species

 

In a series of experiments, del Solar (1966) derived positively and negatively geotactic and phototactic strains of D. pseudoobscura from the same population by running the flies through mazes. Flies from different strains were then introduced into mating chambers (10 males and 10 females from each strain). Matings were recorded. Statistically significant positive assortative mating was found.

 

In a separate series of experiments Dodd (1989) raised eight populations derived from a single population of D. Pseudoobscura on stressful media. Four populations were raised on a starch based medium, the other four were raised on a maltose based medium. The fly populations in both treatments took several months to get established, implying that they were under strong selection. Dodd found some evidence of genetic divergence between flies in the two treatments. He performed mate choice tests among experimental populations. He found statistically significant assortative mating between populations raised on different media, but no assortative mating among populations raised within the same medium regime. He argued that since there was no direct selection for reproductive isolation, the behavioral isolation results from a pleiotropic by-product to adaptation to the two media. Schluter and Nagel (1995) have argued that these results provide experimental support for the hypothesis of parallel speciation.

 

Less dramatic results were obtained by growing D. willistoni on media of different pH levels (de Oliveira and Cordeiro 1980). Mate choice tests after 26, 32, 52 and 69 generations of growth showed statistically significant assortative mating between some populations grown in different pH treatments. This ethological isolation did not always persist over time. They also found that some crosses made after 106 and 122 generations showed significant hybrid inferiority, but only when grown in acid medium.

5.3.7 Selection for Reinforcement in Drosophila melanogaster

 

Some proposed models of speciation rely on a process called reinforcement to complete the speciation process. Reinforcement occurs when to partially isolated allopatric populations come into contact. Lower relative fitness of hybrids between the two populations results in increased selection for isolating mechanisms. I should note that a recent review (Rice and Hostert 1993) argues that there is little experimental evidence to support reinforcement models. Two experiments in which the authors argue that their results provide support are discussed below.

 

Ehrman (1971) established strains of wild-type and mutant (black body) D. melanogaster. These flies were derived from compound autosome strains such that heterotypic matings would produce no progeny. The two strains were reared together in common fly cages. After two years, the isolation index generated from mate choice experiments had increased from 0.04 to 0.43, indicating the appearance of considerable assortative mating. After four years this index had risen to 0.64 (Ehrman 1973).

 

Along the same lines, Koopman (1950) was able to increase the degree of reproductive isolation between two partially isolated species, D. pseudoobscura and D. persimilis.

5.3.8 Tests of the Founder-flush Speciation Hypothesis Using Drosophila

 

The founder-flush (a.k.a. flush-crash) hypothesis posits that genetic drift and founder effects play a major role in speciation (Powell 1978). During a founder-flush cycle a new habitat is colonized by a small number of individuals (e.g. one inseminated female). The population rapidly expands (the flush phase). This is followed by the population crashing. During this crash period the population experiences strong genetic drift. The population undergoes another rapid expansion followed by another crash. This cycle repeats several times. Reproductive isolation is produced as a byproduct of genetic drift.

 

Dodd and Powell (1985) tested this hypothesis using D. pseudoobscura. A large, heterogeneous population was allowed to grow rapidly in a very large population cage. Twelve experimental populations were derived from this population from single pair matings. These populations were allowed to flush. Fourteen months later, mating tests were performed among the twelve populations. No postmating isolation was seen. One cross showed strong behavioral isolation. The populations underwent three more flush-crash cycles. Forty-four months after the start of the experiment (and fifteen months after the last flush) the populations were again tested. Once again, no postmating isolation was seen. Three populations showed behavioral isolation in the form of positive assortative mating. Later tests between 1980 and 1984 showed that the isolation persisted, though it was weaker in some cases.

 

Galina, et al. (1993) performed similar experiments with D. pseudoobscura. Mating tests between populations that underwent flush-crash cycles and their ancestral populations showed 8 cases of positive assortative mating out of 118 crosses. They also showed 5 cases of negative assortative mating (i.e. the flies preferred to mate with flies of the other strain). Tests among the founder-flush populations showed 36 cases of positive assortative mating out of 370 crosses. These tests also found 4 cases of negative assortative mating. Most of these mating preferences did not persist over time. Galina, et al. concluded that the founder-flush protocol yields reproductive isolation only as a rare and erratic event.

 

Ahearn (1980) applied the founder-flush protocol to D. silvestris. Flies from a line of this species underwent several flush-crash cycles. They were tested in mate choice experiments against flies from a continuously large population. Female flies from both strains preferred to mate with males from the large population. Females from the large population would not mate with males from the founder flush population. An asymmetric reproductive isolation was produced.

 

In a three year experiment, Ringo, et al. (1985) compared the effects of a founder-flush protocol to the effects of selection on various traits. A large population of D. simulans was created from flies from 69 wild caught stocks from several locations. Founder-flush lines and selection lines were derived from this population. The founder-flush lines went through six flush-crash cycles. The selection lines experienced equal intensities of selection for various traits. Mating test were performed between strains within a treatment and between treatment strains and the source population. Crosses were also checked for postmating isolation. In the selection lines, 10 out of 216 crosses showed positive assortative mating (2 crosses showed negative assortative mating). They also found that 25 out of 216 crosses showed postmating isolation. Of these, 9 cases involved crosses with the source population. In the founder-flush lines 12 out of 216 crosses showed positive assortative mating (3 crosses showed negative assortative mating). Postmating isolation was found in 15 out of 216 crosses, 11 involving the source population. They concluded that only weak isolation was found and that there was little difference between the effects of natural selection and the effects of genetic drift.

 

A final test of the founder-flush hypothesis will be described with the housefly cases below.

5.4 Housefly Speciation Experiments

 

5.4.1 A Test of the Founder-flush Hypothesis Using Houseflies

 

Meffert and Bryant (1991) used houseflies to test whether bottlenecks in populations can cause permanent alterations in courtship behavior that lead to premating isolation. They collected over 100 flies of each sex from a landfill near Alvin, Texas. These were used to initiate an ancestral population. From this ancestral population they established six lines. Two of these lines were started with one pair of flies, two lines were started with four pairs of flies and two lines were started with sixteen pairs of flies. These populations were flushed to about 2,000 flies each. They then went through five bottlenecks followed by flushes. This took 35 generations. Mate choice tests were performed. One case of positive assortative mating was found. One case of negative assortative mating was also found.

5.4.2 Selection for Geotaxis with and without Gene Flow

 

Soans, et al. (1974) used houseflies to test Pimentel's model of speciation. This model posits that speciation requires two steps. The first is the formation of races in subpopulations. This is followed by the establishment of reproductive isolation. Houseflies were subjected to intense divergent selection on the basis of positive and negative geotaxis. In some treatments no gene flow was allowed, while in others there was 30% gene flow. Selection was imposed by placing 1000 flies into the center of a 108 cm vertical tube. The first 50 flies that reached the top and the first 50 flies that reached the bottom were used to found positively and negatively geotactic populations. Four populations were established:

Population A + geotaxis, no gene flow

Population B - geotaxis, no gene flow

Population C + geotaxis, 30% gene flow

Population D - geotaxis, 30% gene flow

 

Selection was repeated within these populations each generations. After 38 generations the time to collect 50 flies had dropped from 6 hours to 2 hours in Pop A, from 4 hours to 4 minutes in Pop B, from 6 hours to 2 hours in Pop C and from 4 hours to 45 minutes in Pop D. Mate choice tests were performed. Positive assortative mating was found in all crosses. They concluded that reproductive isolation occurred under both allopatric and sympatric conditions when very strong selection was present.

 

Hurd and Eisenberg (1975) performed a similar experiment on houseflies using 50% gene flow and got the same results.

5.5 Speciation Through Host Race Differentiation

 

Recently there has been a lot of interest in whether the differentiation of an herbivorous or parasitic species into races living on different hosts can lead to sympatric speciation. It has been argued that in animals that mate on (or in) their preferred hosts, positive assortative mating is an inevitable byproduct of habitat selection (Rice 1985; Barton, et al. 1988). This would suggest that differentiated host races may represent incipient species.

5.5.1 Apple Maggot Fly (Rhagoletis pomonella)

 

Rhagoletis pomonella is a fly that is native to North America. Its normal host is the hawthorn tree. Sometime during the nineteenth century it began to infest apple trees. Since then it has begun to infest cherries, roses, pears and possibly other members of the rosaceae. Quite a bit of work has been done on the differences between flies infesting hawthorn and flies infesting apple. There appear to be differences in host preferences among populations. Offspring of females collected from on of these two hosts are more likely to select that host for oviposition (Prokopy et al. 1988). Genetic differences between flies on these two hosts have been found at 6 out of 13 allozyme loci (Feder et al. 1988, see also McPheron et al. 1988). Laboratory studies have shown an asynchrony in emergence time of adults between these two host races (Smith 1988). Flies from apple trees take about 40 days to mature, whereas flies from hawthorn trees take 54-60 days to mature. This makes sense when we consider that hawthorn fruit tends to mature later in the season that apples. Hybridization studies show that host preferences are inherited, but give no evidence of barriers to mating. This is a very exciting case. It may represent the early stages of a sympatric speciation event (considering the dispersal of R. pomonella to other plants it may even represent the beginning of an adaptive radiation). It is important to note that some of the leading researchers on this question are urging caution in interpreting it. Feder and Bush (1989) stated:

 

"Hawthorn and apple "host races" of R. pomonella may therefore represent incipient species. However, it remains to be seen whether host-associated traits can evolve into effective enough barriers to gene flow to result eventually in the complete reproductive isolation of R. pomonella populations."

 

5.5.2 Gall Former Fly (Eurosta solidaginis)

 

Eurosta solidaginis is a gall forming fly that is associated with goldenrod plants. It has two hosts: over most of its range it lays its eggs in Solidago altissima, but in some areas it uses S. gigantea as its host. Recent electrophoretic work has shown that the genetic distances among flies from different sympatric hosts species are greater than the distances among flies on the same host in different geographic areas (Waring et al. 1990). This same study also found reduced variability in flies on S. gigantea. This suggests that some E. solidaginis have recently shifted hosts to this species. A recent study has compared reproductive behavior of the flies associated with the two hosts (Craig et al. 1993). They found that flies associated with S. gigantea emerge earlier in the season than flies associated with S. altissima. In host choice experiments, each fly strain ovipunctured its own host much more frequently than the other host. Craig et al. (1993) also performed several mating experiments. When no host was present and females mated with males from either strain, if males from only one strain were present. When males of both strains were present, statistically significant positive assortative mating was seen. In the presence of a host, assortative mating was also seen. When both hosts and flies from both populations were present, females waited on the buds of the host that they are normally associated with. The males fly to the host to mate. Like the Rhagoletis case above, this may represent the beginning of a sympatric speciation.

5.6 Flour Beetles (Tribolium castaneum)

 

Halliburton and Gall (1981) established a population of flour beetles collected in Davis, California. In each generation they selected the 8 lightest and the 8 heaviest pupae of each sex. When these 32 beetles had emerged, they were placed together and allowed to mate for 24 hours. Eggs were collected for 48 hours. The pupae that developed from these eggs were weighed at 19 days. This was repeated for 15 generations. The results of mate choice tests between heavy and light beetles was compared to tests among control lines derived from randomly chosen pupae. Positive assortative mating on the basis of size was found in 2 out of 4 experimental lines.

5.7 Speciation in a Lab Rat Worm, Nereis acuminata

 

In 1964 five or six individuals of the polychaete worm, Nereis acuminata, were collected in Long Beach Harbor, California. These were allowed to grow into a population of thousands of individuals. Four pairs from this population were transferred to the Woods Hole Oceanographic Institute. For over 20 years these worms were used as test organisms in environmental toxicology. From 1986 to 1991 the Long Beach area was searched for populations of the worm. Two populations, P1 and P2, were found. Weinberg, et al. (1992) performed tests on these two populations and the Woods Hole population (WH) for both postmating and premating isolation. To test for postmating isolation, they looked at whether broods from crosses were successfully reared. The results below give the percentage of successful rearings for each group of crosses.

WH × WH - 75%

P1 × P1 - 95%

P2 × P2 - 80%

P1 × P2 - 77%

WH × P1 - 0%

WH × P2 - 0%

 

They also found statistically significant premating isolation between the WH population and the field populations. Finally, the Woods Hole population showed slightly different karyotypes from the field populations.

5.8 Speciation Through Cytoplasmic Incompatability Resulting from the Presence of a Parasite or Symbiont

 

In some species the presence of intracellular bacterial parasites (or symbionts) is associated with postmating isolation. This results from a cytoplasmic incompatability between gametes from strains that have the parasite (or symbiont) and stains that don't. An example of this is seen in the mosquito Culex pipiens (Yen and Barr 1971). Compared to within strain matings, matings between strains from different geographic regions may may have any of three results: These matings may produce a normal number of offspring, they may produce a reduced number of offspring or they may produce no offspring. Reciprocal crosses may give the same or different results. In an incompatible cross, the egg and sperm nuclei fail to unite during fertilization. The egg dies during embryogenesis. In some of these strains, Yen and Barr (1971) found substantial numbers of Rickettsia-like microbes in adults, eggs and embryos. Compatibility of mosquito strains seems to be correlated with the strain of the microbe present. Mosquitoes that carry different strains of the microbe exhibit cytoplasmic incompatibility; those that carry the same strain of microbe are interfertile.

 

Similar phenomena have been seen in a number of other insects. Microoganisms are seen in the eggs of both Nasonia vitripennis and N. giraulti. These two species do not normally hybridize. Following treatment with antibiotics, hybrids occur between them (Breeuwer and Werren 1990). In this case, the symbiont is associated with improper condensation of host chromosomes.

 

For more examples and a critical review of this topic, see Thompson 1987.

5.9 A Couple of Ambiguous Cases

 

So far the BSC has applied to all of the experiments discussed. The following are a couple of major morphological changes produced in asexual species. Do these represent speciation events? The answer depends on how species is defined.

5.9.1 Coloniality in Chlorella vulgaris

 

Boraas (1983) reported the induction of multicellularity in a strain of Chlorella pyrenoidosa (since reclassified as C. vulgaris) by predation. He was growing the unicellular green alga in the first stage of a two stage continuous culture system as for food for a flagellate predator, Ochromonas sp., that was growing in the second stage. Due to the failure of a pump, flagellates washed back into the first stage. Within five days a colonial form of the Chlorella appeared. It rapidly came to dominate the culture. The colony size ranged from 4 cells to 32 cells. Eventually it stabilized at 8 cells. This colonial form has persisted in culture for about a decade. The new form has been keyed out using a number of algal taxonomic keys. They key out now as being in the genus Coelosphaerium, which is in a different family from Chlorella.

5.9.2 Morphological Changes in Bacteria

 

Shikano, et al. (1990) reported that an unidentified bacterium underwent a major morphological change when grown in the presence of a ciliate predator. This bacterium's normal morphology is a short (1.5 um) rod. After 8 - 10 weeks of growing with the predator it assumed the form of long (20 um) cells. These cells have no cross walls. Filaments of this type have also been produced under circumstances similar to Boraas' induction of multicellularity in Chlorella. Microscopic examination of these filaments is described in Gillott et al. (1993). Multicellularity has also been produced in unicellular bacterial by predation (Nakajima and Kurihara 1994). In this study, growth in the presence of protozoal grazers resulted in the production of chains of bacterial cells."

Endret 17. april 2011 av Gabbe

[Coffey]

For å svare trådstarter:

 

Jeg mener ihvertfall selv at det er like "intelligent" å tro, mene eller forestill seg at det kan finnes noe bak det hele, en energi, ultimat sannhet eller hva enn man kan kalle det, som det er å benekte all eksistense av dette.

 

Det er først når man navngir det og går over til en type organisert religion at det blir vanskelig å respektere. Det at man tar ting ut av den løse lufta (eller en bok, hint hint), og mener og tror på ting vi ikke har overhode beviser for er bare så langt unna alt som kan kalles intelligens.

 

Selv kan jeg vel da kalle meg agnostisk innen det å tro på at det kan være noe bak det hele, men ateistisk i forhold til alle slags religioner.

Endret 17. april 2011 av Coffey

[fuzzyboots]

Jeg mener ihvertfall selv at det er like "intelligent" å tro, mene eller forestill seg at det kan finnes noe bak det hele, en energi, ultimat sannhet eller hva enn man kan kalle det, som det er å benekte all eksistense av dette.

Jeg er uenig. Debatten om semantikk er vel i grunn en forutsetning for at dette skal gi mening, men om vi antar en konsensus om begrepet "intelligens", vil jeg påstå at agnostisisme er en mer intelligent posisjon enn gnostisisme.

 

Det er først når man navngir det og går over til en type organisert religion at det blir vanskelig å respektere. Det at man tar ting ut av den løse lufta (eller en bok, hint hint), og mener og tror på ting vi ikke har overhode beviser for er bare så langt unna alt som kan kalles intelligens.

Muligens med enkelte unntak, er ikke religion "navngitt" agnostisisme.

 

Jeg mener spørsmålet om tilstrekkelighet i forbindelse med tro er et spørsmål om hva som er praktisk. Mye som at du ikke kan demonstrere at noe som helst er de facto som det virker å være (se Münchhausen Trilemma), kan ikke religiøse bevise deres gud. Forskjellen er i essens hva som er statistisk, erfaringsmessig - praktisk, å forholde seg til.

Endret 17. april 2011 av fuzzyboots

[LiamH]

Greit at du tror at min mening er subjektiv. Men du trenger ikke å komme med en feil objektiv mening basert på dine egne fakta for å sette meg på plass...

 

Jeg er ikke ute etter å "sette deg på plass". Jeg gir deg min mening om ditt innlegg. Det jeg sier er at evolusjon ikke "bare er en teori" og at det ligger helt forkjellige grunnlag for å støtte/tro på evolusjon enn kreasjonisme. Det som er fakta, er like mye fakta for meg som det er for deg. Hvis ikke er det ikke fakta.

 

Problemet her er at disse to verdenene ikke kan fungere i lag. Den ene er fullstendig ukorrekt i forhold til den andre. Ut fra faktabasert forskning, så ser det dårlig ut for kreasjonismen, desverre, mens kreasjonismen mangler det meste innen fakta og bevis for å virke troverdig. Derfor mener jeg, som nevnt før, at det er andre årsaker til at mennesker velger religion som sitt livssyn. Det respekterer jeg, men å si at evolusjon er "bare en teori" og ikke trenger å stemme, er en drøy påstand hvis man støtter kreasjonismen. Det faller på sin egen urimelighet og er ukorrekt.

 

Du trenger ikke komme med en feil objektiv meninig

 

Neivel... kanskje du kan si noe om hva du mener er feil med min mening (som forsåvidt ikke er objektiv)?

 

 

For å svare trådstarter:

 

Jeg mener ihvertfall selv at det er like "intelligent" å tro, mene eller forestill seg at det kan finnes noe bak det hele, en energi, ultimat sannhet eller hva enn man kan kalle det, som det er å benekte all eksistense av dette.

 

Det er først når man navngir det og går over til en type organisert religion at det blir vanskelig å respektere. Det at man tar ting ut av den løse lufta (eller en bok, hint hint), og mener og tror på ting vi ikke har overhode beviser for er bare så langt unna alt som kan kalles intelligens.

 

Selv kan jeg vel da kalle meg agnostisk innen det å tro på at det kan være noe bak det hele, men ateistisk i forhold til alle slags religioner.

 

Jeg mener at det å benekte all form for tro er vitenskapelig ukorrekt. Man kan ikke ekskludere alle former for ubeviselig overtro, men man kan legge seg helt mot ytterkanten av å si at dette er vanvittig usannsynelig. Derfor mener jeg at en 7'er på 1-7 skalaen av ateisme er arrogant og lite gjennomtenkt. Tenker man vitenskapelig, vil man alltid være åpen for å ta feil, så lenge det er mulighet for det og man avviser ingenting blankt før man har fått det konstatert utover enhver tvil. Bare min mening.

Endret 17. april 2011 av LiamH

[kris98]

Ateisme er en mangel på tro, ikke en fornektelse av tro. Om det bevises at en religion er korrekt, så blir jeg med uten problemer. Inntil den gang ser jeg ingen grunn til å tro på noe. Forstår ikke hvordan det er arrogant.

[fuzzyboots]

http://en.wikipedia.org/wiki/Negative_and_positive_atheism

[LiamH]

Ateisme er en mangel på tro, ikke en fornektelse av tro. Om det bevises at en religion er korrekt, så blir jeg med uten problemer. Inntil den gang ser jeg ingen grunn til å tro på noe. Forstår ikke hvordan det er arrogant.

 

Vel, her er semantikk i fokus igjen og jeg har alltid syntes at "fravær av tro" mangler en tolkningsdel hos individet som inntar dette livssynet. Jeg er åpen for å ta feil her, så dette sier jeg kun for å få tilbakemeldinger som kan få meg til å forstå dette bedre. Dette har sikkert vært nevnt utallige ganger fra før og jeg har også diskutert dette før, men jeg får det ikke til å henge på greip.

 

Hvis noen har "fravær av tro", så er dette fordi det ikke finnes grunner til å tro på dette. Er ikke det å si "dette tar jeg ikke en gang stilling til"? Det å ikke ta stilling til problemstillingen i det hele tatt er et valg som er kommet av en tankerekke der man ser over fakta og ikke tar guder med i sitt livssyn. Er ikke det å "fornekte" eller ekskludere noe på grunnlag av at noe er så "virkelighetsfjernt" at man avviser det så til de grader at man ikke en gang vil forholde seg til det?

 

P.s: Vær så snill å ikke lim inn en link. Kom heller med personlige meninger.

Endret 18. april 2011 av LiamH

[cuadro]

Er ikke det å si "dette tar jeg ikke en gang stilling til"? Det å ikke ta stilling til problemstillingen i det hele tatt er et valg som er kommet av en tankerekke der man ser over fakta og ikke tar guder med i sitt livssyn. Er ikke det å "fornekte" eller ekskludere noe på grunnlag av at noe er så "vi

 

Ganske enkelt: Nei. Dette har kun med ærlighet å gjøre. I de fleste tilfeller hvor det er relevant å påpeke betydningen av ateisme, er det fordi individet som gjør dette nettopp er ærlig i sin tankerekke. "Jeg tror ikke på gud, eller Gud, men herlighet... Jeg vet jo ikke."

 

Å si at dette er en fornektelse, må da forstås å ganske enkelt være feil.

Endret 18. april 2011 av cuadro

[bolleboi]

Ateisme er en mangel på tro, ikke en fornektelse av tro. Om det bevises at en religion er korrekt, så blir jeg med uten problemer. Inntil den gang ser jeg ingen grunn til å tro på noe. Forstår ikke hvordan det er arrogant.

 

Vel, her er semantikk i fokus igjen og jeg har alltid syntes at "fravær av tro" mangler en tolkningsdel hos individet som inntar dette livssynet. Jeg er åpen for å ta feil her, så dette sier jeg kun for å få tilbakemeldinger som kan få meg til å forstå dette bedre. Dette har sikkert vært nevnt utallige ganger fra før og jeg har også diskutert dette før, men jeg får det ikke til å henge på greip.

 

Hvis noen har "fravær av tro", så er dette fordi det ikke finnes grunner til å tro på dette. Er ikke det å si "dette tar jeg ikke en gang stilling til"? Det å ikke ta stilling til problemstillingen i det hele tatt er et valg som er kommet av en tankerekke der man ser over fakta og ikke tar guder med i sitt livssyn. Er ikke det å "fornekte" eller ekskludere noe på grunnlag av at noe er så "virkelighetsfjernt" at man avviser det så til de grader at man ikke en gang vil forholde seg til det?

 

P.s: Vær så snill å ikke lim inn en link. Kom heller med personlige meninger.

 

Jeg er uenig, selvom jeg har fravær av tro mangler jeg ikke en tolkningsdel. Når jeg tar stilling til religion og guder i dag ser jeg ikke bare på det som usannsynlig, og forfekter det av den grunn. Slik jeg tenker det da, Dersom det var en større "kraft" eller noe mer ved verden vi ikke kan sette fingeren på enda, så er det hvertfal ingen gud tilhørende noen av dagens religioner. Guder er bare figuerer skapt for å forklare det uforklarlige(og kontrollere mennesker, bare se hvor mye syke ting vi har gjort oppgjennom årene fordi noen har lurt oss til å "tro"). Religion er bygget på redselen til mennesket om det ukjente, spesielt da døden. Noe vi frykter mere enn noe annet, vi vet ikke hva som skjer etter døden, ergo er det lett for religioner å kontrollere ditt virkelige liv. Gjør ditt eller datt hvis ikke havner du i helvete, eller gjør ditt og datt så kommer du til himmelen.

 

Det virker som om du syntes at jeg har et trangere syn fordi jeg ikke tror på gud. Jeg mener at det er motsatt, at de som er religiøse er de som har et trangere syn, de forfekter alt annet enn sin gud og tro. Mangel på kritisk tankegang vil aldri være positivt i det lange løp

[soulless]

Er ikke det å si "dette tar jeg ikke en gang stilling til"? Det å ikke ta stilling til problemstillingen i det hele tatt er et valg som er kommet av en tankerekke der man ser over fakta og ikke tar guder med i sitt livssyn. Er ikke det å "fornekte" eller ekskludere noe på grunnlag av at noe er så "vi

 

Ganske enkelt: Nei. Dette har kun med ærlighet å gjøre. I de fleste tilfeller hvor det er relevant å påpeke betydningen av ateisme, er det fordi individet som gjør dette nettopp er ærlig i sin tankerekke. "Jeg tror ikke på gud, eller Gud, men herlighet... Jeg vet jo ikke."

 

Å si at dette er en fornektelse, må da forstås å ganske enkelt være feil.

 

Man kan vel også svare at selve spørsmålet i grunnen er meningsløst, for hvordan skal man diskutere eksistensen av noe uten en klar definisjon av hva dette "noe" er?

 

Merker selv at jeg har en aldri så liten forkjærlighet for ignostisisme;

https://secure.wikimedia.org/wikipedia/en/wiki/Ignosticism , noe jeg ut fra dine tidligere argumenter i andre tråder mistenker at du også til en viss grad har.

[cuadro]

Helt riktig, soulless. Og det er akkurat den mynten jeg som oftest forsøker å kaste i fleisen selv, men jeg forsøkte i hovedsak å ta for meg de "fleste tilfeller".

 

Jeg ser også for meg at i så tilfelle kan det være greit å gi et skille mellom diskriptive guder fra en eller annen "hellig tekst", og de utallige udefinerte guder. Jeg vil for eksempel føle meg mye nærmere "ignostisisme" henhold en personlig gud som jeg bare hører taler om fra et individ. Men jeg vil samtidig brånekte for den Bibelske Gud - slik jeg tolker den - selv om jeg ikke kan gjøre det med "den Bibelske Gud" slik andre kan tolke den.

 

Men jeg vil forstå dette som to sider av samme mynt.