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veracity of evolution

 
 
odenskrigare
 
  1  
Reply Sat 29 Aug, 2009 12:04 pm
@Aedes,
Aedes;86621 wrote:
Amazing how authoritatively people can seem about things they are totally ignorant about and disinterested in.


I can quote scientists too

"Ignorance more frequently begets confidence than does knowledge." - Charles Darwin
0 Replies
 
prothero
 
  1  
Reply Sat 29 Aug, 2009 12:36 pm
@odenskrigare,
The assertion that evolution is a blind and indifferent process is a philosophical specualtion not a fact or even a scientfic theory.

A theory is a plausible explanation for a large number of observed facts.
Evolution is about as well confirmed a theory as any scientific theory.

You can not however, demonstrated evolution by direct experiment because it is a historical and unrepeatable process. It is in some respect then different than say the trajectory of a bullet.

Materialists, mechanists, determinists and reductionists claim too much for evolution. Supernatural theists claim too little. You need to acknowledge the difference between science (physics) and metaphysics. Too many try to assert their metaphysical biases as scientific endeavor.
Aedes
 
  1  
Reply Sat 29 Aug, 2009 01:11 pm
@prothero,
prothero;86644 wrote:
You can not however, demonstrated evolution by direct experiment because it is a historical and unrepeatable process.
That's true for geology and linguistics as well, yet funny how no one wants to start a thread about establishing the age of the Grand Canyon or the proto-indoeuropean diaspora.
0 Replies
 
Pathfinder
 
  1  
Reply Sat 29 Aug, 2009 01:22 pm
@odenskrigare,
And yet nobody responds to the argument of why there is not a thousand variances of evolutionary mutations available in this world right now for people to observe.

If evolution has been going throuhg this process for millions of years of mutatioin after mutation, why are we not seeing many thousands of inbetween groups of species?

There should be humans walking this planet that are somewhere in between the stages that you are proposing are occurring.

I dont see any. I hear stories about a bigfoot, but if whaT EVOLUTION SAYS HAS BEEN HAPPENING IS FACTUAL WHY ARENMT THERE MANY VARIOIUS STAGES OF THE EVOLUTIONARY PROCESS AROUND FOR US TO SEE RIGHT NOW. wHAT IS THIS , A LULL IN EVOLUTION RIGHT NOW AND ITS GOING TO KICK IN AGAIN SOMEWHERE UP THE ROAD?
SORRY bout the caps but i aint goin over all that again, lol.
Lily
 
  1  
Reply Sat 29 Aug, 2009 02:19 pm
@Pathfinder,
Pathfinder;86650 wrote:
And yet nobody responds to the argument of why there is not a thousand variances of evolutionary mutations available in this world right now for people to observe.

If evolution has been going throuhg this process for millions of years of mutatioin after mutation, why are we not seeing many thousands of inbetween groups of species?

Did you skip science classes? Or forget about your toenails? Anyway, there are no such thing as inbetween-species, every individual works for the moment, it's the survival of the fittest, not the one that would be the fittest in a million years. You can't know where species are going, so you can't say "oh, that racoon doesn't look like it's on its way to becoma a whale at all, I guess evolution is fake then..."
And, we do see what you would call inbetween groups of species. Look at a poodle, and then look german shepherd dog. They look quite different to me...
0 Replies
 
ACB
 
  1  
Reply Sat 29 Aug, 2009 02:19 pm
@prothero,
prothero;86644 wrote:
The assertion that evolution is a blind and indifferent process is a philosophical specualtion not a fact or even a scientfic theory.

A theory is a plausible explanation for a large number of observed facts.
Evolution is about as well confirmed a theory as any scientific theory.


This is a contradiction.
odenskrigare
 
  1  
Reply Sat 29 Aug, 2009 02:40 pm
@Pathfinder,
Pathfinder;86650 wrote:
And yet nobody responds to the argument of why there is not a thousand variances of evolutionary mutations available in this world right now for people to observe


Tamiflu no longer works for dominant flu strain - Los Angeles Times

Pathfinder;86650 wrote:
If evolution has been going throuhg this process for millions of years of mutatioin after mutation, why are we not seeing many thousands of inbetween groups of species?


you can see them, if you actually look

that's what Darwin saw in the Galapagos

that's what can make taxonomy difficult

Pathfinder;86650 wrote:
There should be humans walking this planet that are somewhere in between the stages that you are proposing are occurring


no but there are still apes

another intelligent ape species could emerge but history stretches back only for a few paltry millenia so it's too early to say

Pathfinder;86650 wrote:
I dont see any. I hear stories about a bigfoot, but if whaT EVOLUTION SAYS HAS BEEN HAPPENING IS FACTUAL WHY ARENMT THERE MANY VARIOIUS STAGES OF THE EVOLUTIONARY PROCESS AROUND FOR US TO SEE RIGHT NOW. wHAT IS THIS , A LULL IN EVOLUTION RIGHT NOW AND ITS GOING TO KICK IN AGAIN SOMEWHERE UP THE ROAD?
SORRY bout the caps but i aint goin over all that again, lol.


you're acting like evolution acts at the same time scale as a microwave oven, but for what it's worth

[indent]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:
[INDENT] "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."
[/INDENT] 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 acuminata5.8 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.[/indent]


Observed Instances of Speciation
0 Replies
 
Pathfinder
 
  1  
Reply Sat 29 Aug, 2009 03:21 pm
@odenskrigare,
where are the so called mutations of human life somewhere between the apes and the human today?

Where are the mutational stages between all of these animal species that are on the planet today. There should be many hundred of various stages romping across the planet. Where are they. These things that you are showing are either fossils or a half dozen examples of animals that could be exactly what they are.

Where are the stages of mutation that should be seen across the animal kingdom? There should be millions of various stages?

How can you say that life has been going through a process of evolution over million sof years , and yet you are only able to come up with a few examples of what might possibly be a species that may have gone through some genetic mutation.

There should be millions of them prancing around all ovewr the planet. TYhis has been going on all along for millions of years with virtusally every living creature on the earth and all you can com,e up with is a feew species off of one island that have probably lived there like that for a million years thesmselves.

show me the MONEY!
Berner
 
  1  
Reply Sat 29 Aug, 2009 04:09 pm
@Pathfinder,
Pathfinder;86689 wrote:
where are the so called mutations of human life somewhere between the apes and the human today?

Where are the mutational stages between all of these animal species that are on the planet today. There should be many hundred of various stages romping across the planet. Where are they. These things that you are showing are either fossils or a half dozen examples of animals that could be exactly what they are.

Where are the stages of mutation that should be seen across the animal kingdom? There should be millions of various stages?

How can you say that life has been going through a process of evolution over million sof years , and yet you are only able to come up with a few examples of what might possibly be a species that may have gone through some genetic mutation.

There should be millions of them prancing around all ovewr the planet. TYhis has been going on all along for millions of years with virtusally every living creature on the earth and all you can com,e up with is a feew species off of one island that have probably lived there like that for a million years thesmselves.

show me the MONEY!



YouTube - How To Shut Up Pesky Creationists
0 Replies
 
odenskrigare
 
  1  
Reply Sat 29 Aug, 2009 04:10 pm
@Pathfinder,
Pathfinder;86689 wrote:
where are the so called mutations of human life somewhere between the apes and the human today?


there aren't any

but you're both strawmanning evolution and affirming the consequent

if the theory of evolution were invalid, then there would be no new hominids
there are no new hominids
therefore the theory of evolution is invalid

it's a bogus argument

Pathfinder;86689 wrote:
Where are the mutational stages between all of these animal species that are on the planet today. There should be many hundred of various stages romping across the planet


there are. life is incredibly diverse. hundreds? try two million formally cataloged species. and those are just the ones we know, we probably don't even know most of the species on Earth

Pathfinder;86689 wrote:
Where are they. These things that you are showing are either fossils or a half dozen examples of animals that could be exactly what they are


huh?

Pathfinder;86689 wrote:
Where are the stages of mutation that should be seen across the animal kingdom? There should be millions of various stages?


there are

Pathfinder;86689 wrote:
How can you say that life has been going through a process of evolution over million sof years , and yet you are only able to come up with a few examples of what might possibly be a species that may have gone through some genetic mutation


not "might be," a number are confirmed (yes, evolution is a fact), and I'm guessing that we've only observed a relative few instances of speciation since we only started looking a little more than 100 years ago or so

Pathfinder;86689 wrote:
show me the MONEY!


http://www.saabhistory.com/blog/wp-content/uploads/2009/02/kronor.jpg

---------- Post added 08-29-2009 at 06:22 PM ----------

Berner posted a video that shows how two chromosome pairs from the great apes fused in humans but I guess you'll ignore that too
0 Replies
 
ACB
 
  1  
Reply Sat 29 Aug, 2009 04:38 pm
@Pathfinder,
Pathfinder;86545 wrote:
I have also made it clear that the juncture between life and death is a crucial point in understanding evolution because to promote evolution one must consider that instant that life emerges as they are saying and what happens to it at that precsie miilisecond that causes it to evolve differently from its host. Hense there is an emergence involved that borders this fine line between NOT alive and alive that is the balancing act of the entire hypothesis.

And on that borderline between life and Non life is also the other extreme, which is death.

I see the whole process as exisitng between two fine lines. The first being the fine line between non life and instantaneous emergence of life, the spark or initiation of the process that follows. The second fine line being the end of that process which mimics the first by being suddenly and instantaeously sudden loss of that life.


You earlier asked (post #125):

"With regard to the evolution of an organism, is it not at the stage of conception that these mutations are being altered?"

and Aedes replied (#126):

"Not necessarily. They just have to enter the germline somewhere to be transmissible."

This denies any necessary chronological link between mutation and conception, or (by extension) between mutation and death. This is of fundamental importance in the context of your argument. Evolution and death are two quite separate matters.

Also, if there were a non-physical life force, it would interact with living bodies in the same way (entering at conception and leaving at death) regardless of whether there were ever any mutations, would it not? That is another reason why I think the conception/death/life-force question is separate from the question of evolution.
0 Replies
 
odenskrigare
 
  1  
Reply Sat 29 Aug, 2009 04:53 pm
@odenskrigare,
if I got pwned so many times, so hard I'd give up posting tbh
0 Replies
 
prothero
 
  1  
Reply Sat 29 Aug, 2009 05:04 pm
@ACB,
ACB;86662 wrote:
This is a contradiction.


I do not think so. Not if you read carefully enough.
It is the "blind and indifferent" part that makes the difference.
0 Replies
 
richrf
 
  1  
Reply Sat 29 Aug, 2009 05:25 pm
@Aedes,
Aedes;86621 wrote:
Evolutionary biology and the theory of evolution are not "Darwin's Evolutionary ideas". If you think so, then you've missed 150 years of amassed research.


I am speaking directly about Darwin's Theory. I always have been from the beginning, calling it Darwin's Speculation.

Now, if you are telling me that things evolve. That is fine. I observe things change every day in my life. Some people observe things change under a microscope. Some observe it through a telescope. Some observe it with their eyes. Thousands of years ago, people proclaimed things are in flux. The only difference is what is being observed.

However, there is a BIG difference and a BIG leap from this to suggesting that anyone knows how life formed. I am not ready to make that leap. And I would love to see an experiment that reproduces what was going on millions of years ago. That would be something. At the very least, someone would have to intuit the conditions that existed a millions of years ago.

When I say something, I like to be precise and crititical:

We have two proposals for how life emerged:

1) Life emerged from matter.

2) Life emerged from living processes.

Both are claimed to be facts. I would like to know which of these two are facts or are they both facts, or are neither facts. If either or both of these are facts, I would like to know what makes them facts.

Both of these pertain to Darwin's Theory, and I am not that concerned about a general theory that things evolve. I think everything evolves, though I realize that there are some philosophical circles believe that there is a constant in nature that does not evolve.

So, if I can have a clear and precise answer on these two statements, both being set forth as facts, I would appreciate it.

Rich

---------- Post added 08-29-2009 at 06:31 PM ----------

prothero;86644 wrote:
A theory is a plausible explanation for a large number of observed facts. Evolution is about as well confirmed a theory as any scientific theory.


For me a plausible explanation is different from a fact. Are they the same? The whole discussion began with several forum members declaring evolution as a fact. Which is it? A plausible explanation or a fact?

When you say that evolution is a well confirmed theory, can you define for me how you define evolutionary theory? What I object to is seeing something in a microscope change (I see things change all the time), and then declare this is what happened millions of years ago. So, I would like to know what you mean by evolutionary theory.

And to be explicit, do you believe that Darwin's Theory of the Origin of the Species is a Theory or Fact? I am using your definition of Theory. I do not know yet what your definition of fact is?

Thanks.

Rich
Berner
 
  1  
Reply Sat 29 Aug, 2009 05:50 pm
@richrf,
richrf;86718 wrote:
I am speaking directly about Darwin's Theory. I always have been from the beginning, calling it Darwin's Speculation.

...

We have two proposals for how life emerged:

1) Life emerged from matter.

2) Life emerged from living processes.

Both are claimed to be facts. I would like to know which of these two are facts or are they both facts, or are neither facts. If either or both of these are facts, I would like to know what makes them facts.

Both of these pertain to Darwin's Theory, and I am not that concerned about a general theory that things evolve. I think everything evolves, though I realize that there are some philosophical circles believe that there is a constant in nature that does not evolve.


No Darwin's original theory never talked about how life formed and evolutionary theory today has nothing to say about it. Darwin and Evolutionary theory are only concerned with the biodiversity we see.

You're arguing against Abiogenesis which is another facet of biology/biochemistry/chemistry all together.

richrf;86718 wrote:

For me a plausible explanation is different from a fact. Are they the same? The whole discussion began with several forum members declaring evolution as a fact. Which is it? A plausible explanation or a fact?


Fact: Organisms change over time to become wholy different from the original point of observation.

Explanation: Natural selection accounts for these observed changes.

richrf;86718 wrote:

When you say that evolution is a well confirmed theory, can you define for me how you define evolutionary theory? What I object to is seeing something in a microscope change (I see things change all the time), and then declare this is what happened millions of years ago. So, I would like to know what you mean by evolutionary theory.


Change via natural selection.

richrf;86718 wrote:

And to be explicit, do you believe that Darwin's Theory of the Origin of the Species is a Theory or Fact? I am using your definition of Theory. I do not know yet what your definition of fact is?

Thanks.

Rich


Theories are used to explain something that hasn't yet been observed. Hypotheses attempt to explain something not yet understood. Facts aren't really debatable.

Example:

I hold my shoe 5 feet in the air and let go.

Fact: The shoe falls to the ground.
Hypothesis: There is a force pulling my shoe downwards.
Theory: Two objects have a gravitational force of attraction such that:

F(r) = GmM/r^2

Where r is the distance between the two objects, G is the universal gravitation constant, m is the mass of the smaller object (shoe), M is the mass of the larger object (Earth).

Obviously this is Newtonian in nature and doesn't take relativity into effect but it's just for illustrative purposes.

As for Darwin's original postulation it's reached the highest level anything can get to in science, a theory, since it's tried tested and true. The fact that things evolve from prior life forms isn't really debatable.
Pathfinder
 
  1  
Reply Sat 29 Aug, 2009 06:34 pm
@odenskrigare,
I think that Oden hates to get owned as he likes to call it and we have him in a corner with their inability to define the emergence of life.

He had no response to KJs suggestion that life comes from potassium, and he has no other response other than life emerges from earth matter now.

Face it, they simply cannot answer this crucial question and in order to avoid being owned, he tries desperately to say that he has owned first, its like bantering with a child.

Forget the games and just answer the danged questions if you can, If you cant than either run and hide or at least try to be evasive and we will try harder to pin you down,,, but geeez, owned????? wtf

just answer the question and stop embarrassing yourself will ya. I am embarrassed for you.

The only thing you own here is the opportunity to show some maturity and gain some respect and maybe a few friends along the way.

Now instead of saying that life comes from the dirt, or the 'process' or THAT, try something else.
0 Replies
 
odenskrigare
 
  1  
Reply Sat 29 Aug, 2009 06:35 pm
@odenskrigare,
Berner way to go now he's going to go off about how Newtonian physics is totally useless after relativity and quantum physics (two other fields he doesn't understand in any more than a superficial way) despite the fact that he is surrounded by products of engineering based on icky Newtonian / Lagrangian type deterministic mechanics

---------- Post added 08-29-2009 at 08:41 PM ----------

Pathfinder;86730 wrote:
I think that Oden hates to get owned as he likes to call it and we have him in acorner with their inability to define the emergence of life


if you understood even high school level biology (seriously), you'd know who's getting owned here

Pathfinder;86730 wrote:
just answer the question


what question?
0 Replies
 
richrf
 
  1  
Reply Sat 29 Aug, 2009 06:44 pm
@Berner,
Berner;86722 wrote:
You're arguing against Abiogenesis which is another facet of biology/biochemistry/chemistry all together.


Yes, I was debating the above declarations. If anyone wants to comment on them, I would appreciate it.

Berner;86722 wrote:
Fact: Organisms change over time to become wholy different from the original point of observation.


This is what I have also observed. And I would agree.

Berner;86722 wrote:
Explanation: Natural selection accounts for these observed changes.


OK. It is an plausible explanation. I would agree with that also. However, what is considered plausible needs to be defined more precisely. I would say that I have talked to people who do not think it is plausible, and they may represent the majority of the population on earth.

Berner;86722 wrote:
Change via natural selection.


Are you describing this as a well confirmed, theory of what happened in the past and how species evolved? If so, can you give me a brief description of how this was confirmed?

Berner;86722 wrote:
Theories are used to explain something that hasn't yet been observed. Hypotheses attempt to explain something not yet understood. Facts aren't really debatable.


Would you put Relativity and Quantum theories which make no representation of what happened in the past, but are purely predictive in nature, in the same class as theories such as species evolution theories which purport to explain what happened in the past. I realize that they may be both theories, but a theory that is purely predictive to me is completely different than one that suggests something may have happened millions of years ago. How does one distinguish the two, or is it necessary to distinguish the two.

Berner;86722 wrote:
Example:

I hold my shoe 5 feet in the air and let go.

Fact: The shoe falls to the ground.
Hypothesis: There is a force pulling my shoe downwards.
Theory: Two objects have a gravitational force of attraction such that:

F(r) = GmM/r^2

As for Darwin's original postulation it's reached the highest level anything can get to in science, a theory, since it's tried tested and true. The fact that things evolve from prior life forms isn't really debatable.


Yes, but the example you gave does not purport to explain who made the shoe, how you purchased it, and what gave you the idea to throw it in the air. The two, for me, are completely different. Now, if you told me that Newton's Law not only predicts that the shoe will fall to the ground and the shoe was purchased at Zappo and was shipped via UPS because UPS was the cheapest way to ship it, then I would have a problem. The former part is predictive and repeatable, the latter part is pure speculation.

Thanks for helping me understand your perspective. I hope I have explained mine clearly even if we may disagree.

Rich

---------- Post added 08-29-2009 at 07:47 PM ----------

Pathfinder;86730 wrote:
He had no response to KJs suggestion that life comes from potassium, and he has no other response other than life emerges from earth matter now.


I cannot quite figure out what everyone is talking about, which is why I am trying to get clear explanations. It appears to me that most, though not all, forum members are working on the definition that theories are plausible explanations. What defines plausible is what I am trying to understand at this point.

For me plausible is predictive and repeatable. It is not trying to explain what happened millions of years ago. But the is what I am trying to figure out.

Rich
0 Replies
 
Pathfinder
 
  1  
Reply Sat 29 Aug, 2009 06:54 pm
@odenskrigare,
Again as I have pointed out so many times here, what these people are talking about is AFTER the fact. All of this biologic process and function is AFTER life has been given.

They cannot answer the question of the concept of life other than what life is AFTER it is conceived.

Biology= the study of life AFTER its conception

The only answers they have come up with is that life comes from potassium, life comes from the earth matter, and that life comes from the process of life.

We may have to rest our case here as well and call it a day unless they can figure out how to respond sensibly.

Oh and Oden, no no I am not going to say you got OWNED, I was just going to say that when I was in high school taking biology we were clearly taught that it was hypothetical theory. Much more is known today, but nothing that can declare it as a factual process of life.
Aedes
 
  1  
Reply Sat 29 Aug, 2009 07:30 pm
@Pathfinder,
Pathfinder;86650 wrote:
And yet nobody responds to the argument of why there is not a thousand variances of evolutionary mutations available in this world right now for people to observe.
There are. Feel free to look up some haplotype maps. :brickwall:
0 Replies
 
 

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