Speciation? III

Response to Section 5.4, "Housefly Speciation Experiments"

Response to Section 5.4.1, "A Test of the Founder-flush Hypothesis Using Houseflies"


Summary: Experiments testing the founder-flush model of speciation using houseflies found only "marginal significance for positive assortative mating." Biological changes observed amounted to loss of certain courtship behaviors which would probably not be advantageous in the wild, and is not evidence that Darwinian evolution can produce significant biological change.



The paper cited in this section of the FAQ (Meffert and Bryant, 1991) established six lines of houseflies to purportedly test the founder-flush model. After modeling five founder-flush cycles, "[o]nly two cases of significant assortative mating were detected."
95 One of those two cases entailed negative assortative mating where individuals prefer mates from other lines, which obviously would not preserve isolation between those two particular lines in nature. Positive assortative mating was observed between lines 1a and 4b, although they called this only "marginal significance for positive assortative mating."96

The most change they reported in this experiment was premating isolation, pertaining to changes in courtship behavior. However, this also included "loss of specific courtship behavior"
97 in various lines. It’s not clear that the observed changes would be advantageous in the wild. In particular, it has been suggested that the new forms would be less fit, as "Kaneshiro (1980, 1983) proposed that bottlenecks may cause the loss of specific courtship behaviors such that derived males would be discriminated against when competing with ancestral males for ancestral females."98 They find that "[t]his case would appear to support Kaneshiro's hypothesis such that the control females discriminated against 1a males which had a reduction in courtship element utilization."99 Such loss of courtship behaviors thus might not be preserved in nature. In any case, loss of function is not a compelling evolutionary mechanism for speciation; loss-of-function examples are not good evidence that Darwinian evolution can build complexity

In fact, it's not even clear that the ability of males to perform these courtship behaviors was lost. They observe that the observed loss might have been an artifact of more rapid mating: "The mechanism for this unidirectional pattern may have been that females of the bottleneck lines accepted males at an earlier point in courtship such that the last behaviors to be executed in courtship, KICK and WING OUT, were omitted."
100

In any case, no postmating barriers were reported and no significant biological change was reported.

Finally, Meffert and Bryant warn that a major obstacle to the founder-flush model of speciation is that during the "founder" phase where the population goes through a bottleneck, "[i]f founder lines are to be successful in nature they must overcome the initial effects of inbreeding depression, otherwise their establishment as a viable population may be seriously hindered."
101 Interestingly, they suggest that the one observed example of positive assortative mating in their experiments may have resulted from such an inbreeding depression: 28

"Because slow mating in 1b and 4a was associated with some degree of inbreeding depression in egg-to-adult viability (Bryant
et al., 1990), the positive deviations along the first principal axis may represent a trend for coordinated inbreeding depression across suites of traits (egg-to-adult viability, general mating propensity, and complexity of courtship)."102

So it’s not entirely clear that the one example of premating isolation observed in the experiment entailed advantageous biological change. In any case, the rarity of reproductive isolation observed in this experiment, and the low degree and potentially deleterious nature of biological change observed do not support the claim that evolutionary mechanisms can produce significant biological change.


Response to Section 5.4.2, "Selection for Geotaxis with and without Gene Flow"


Summary: Mating experiments between races of houseflies produced only "incipient" reproductive isolation. The only biological change detected was the insignificant behavioral question of whether the fly chose to fly upward or downward in a tube. Reproductive isolation was not complete and speciation was not claimed to have occurred. Significant biological change also was not observed.



This section of the FAQ cites a paper (Soans
et al., 1974) which tests a model of speciation which proceeds first by "formation of races in subpopulation," and then second, by "the establishment of reproductive isolation."103 Reproductive isolation is said to arise when "selection began to operate against the hybrids."104 The experiment used strong artificial selection for flies which chose to fly either up or down in a vertical tube. Four races of houseflies (Musca domestica) were then established:

Race A: 50 flies that flew upward (i.e. pure selection of upward flies)

Race B: 50 flies that flew downward (i.e. pure selection of downward flies)

Race C: 35 flies that flew upward and 15 that flew downward (i.e. 30% gene flow; partial selection of upward flies)

Race D: 35 flies that flew downward and 15 that flew upward (i.e. 30% gene flow; partial selection of downward flies)

All four populations showed assortative mating where they preferred to mate with members of their own race. However, reproductive isolation was not complete and was called merely "incipient."

Thus, the most that was observed was partial premating isolation. The only biological change that was observed was the insignificant behavioral question of whether the fly chose to fly upward or downward in a tube. But since viable and fertile offspring could still be produced, it’s not clear that this entailed any significant form of biological change. Thus, there is only selection "against the hybrids" due to partial premating isolation, not because the two populations had diverged to the point that interbreeding was impossible. 29


The authors acknowledge, however, that since only partial reproductive isolation was achieved, "results of our experiments are far from conclusive in demonstrating speciation via either sympatric or allopatric conditions."
105 Once again, we see only partial reproductive isolation and insignificant biological change arising.

Another paper cited by the FAQ (Hurd and Eisenberg, 1975) performed a similar experiment except they allowed for 50% gene flow in races C and D. They found similar results but asked why selection for a geotactic response (e.g., upward or downward flying flies) would cause such reproductive isolation. They speculate that "It is more likely that by selecting for geotactic response, some other (e.g., behavioral) response which served to differentiate mating types was responsible for the degree of reproductive isolation observed here."
106 This makes it clear that the exact behavioral mechanism which caused reproductive isolation in these experiments is unknown, making it difficult to claim that these studies have established conclusively that significant behavioral change evolved.

Response to Section 5.5, "Speciation Through Host Race Differentiation"


The FAQ states that "differentiated host races may represent incipient species," but as we will see in the following two examples, complete reproductive isolation is not observed and low levels of biological change have arisen.


Response to Section 5.5.1, "Apple Maggot Fly (Rhagoletis pomonella)"


Summary: The FAQ suggests a new species evolved when parasitic flies on hawthorn trees invaded a new type of tree (apples). The two populations form viable hybrids in the lab and thus postzygotic isolation is not apparent. Moreover, the studies leave open the live possibility that the flies "represent a single panmictic population," where both groups interbreed in nature. The populations of flies are called "races" that are only "partially reproductively isolated"; speciation is not established. While some change in allele frequencies is observed, significant morphological change is not claimed to have occurred. The FAQ calls this case "very exciting" but the technical literature it cites is more measured and objective, calling this example "controversial."



In what the FAQ calls "a very exciting case," it discusses claims that the apple maggot fly (
Rhagoletis pomonella) has invaded new trees, and "may represent the early stages of a sympatric speciation event." Clearly then, the FAQ admits that it does not show a full speciation event.

Previously, the fly was only known to invade hawthorn trees, but it is now known to invade other trees—all of them also within the family Rosaceae—including apples, cherries, roses, and pears. Questions have arisen as to whether flies that live on apple trees are forming a new species compared to those that live on hawthorn trees. If some populations prefer one tree over another, then reproductive isolation could occur. But the evidence in this case is far from clear.

One paper cited by the FAQ (McPheron
et al., 1988) notes that "speciation by the formation of host races (parasite populations associated with different plant or animal hosts) has been the 30

subject of great controversy"
107 because "it has been difficult to demonstrate the existence of host races, much less prove that host races are evolving toward species status."108 Likewise, another paper cited by the FAQ (Prokopy et al., 1988) repeatedly calls claims that incipient reproductive isolation is arising "controversial," since previous studies have been inconclusive:

"Two previous studies comparing behavioral responses of female
R. pomonella assayed in groups hinted at small differences in the pattern of host fruit acceptance between hawthorn and apple origin flies … On the other hand, Prokopy et al. (1985) found no differences in pattern of acceptance of a variety of fruit types among populations of R. pomonella originating from apple in Nova Scotia, Massachusetts, Michigan, and Oregon."109

Prokopy
et al. (1988) reported experimental results that were unexpected if sympatric divergence is occurring. Female apple maggot flies preferred to lay eggs in the fruit of hawthorn trees over apple trees regardless of whether they originated on hawthorn or apple trees, leading the paper to conclude that "[t]he results of this experiment again strongly indicated that hawthorn is a significantly more acceptable fruit than apple."110 Likewise, "Males of both larval origins remained on hawthorn fruit significantly longer than on apples."111 In both cases, apple-born females preferred apples more than hawthorn-born females, and apple-born males preferred apples more than hawthorn-born males. Similarly, "Survival from egg to pupal stages was significantly higher for flies of both host origins in hawthorn than apple fruit."112

This example therefore does not show that somehow apple maggot flies have evolved an affinity for apple trees over hawthorn trees. If both populations can accept and even prefer hawthorn trees, this raises the question of whether there has been any significant evolution. Clearly complete reproductive isolation does not exist in nature. They speculate that there is only "some degree of restriction in gene flow" between the two types, but they note that it’s hard to explain why this exists: "Of particular interest to us is an explanation of how gene flow is restricted in face of the ability of both apple and hawthorn origin flies to accept hawthorn to an equal degree."
113 Neither reproductive isolation nor significant biological change has been established by this paper.

In fact, another study cited by the FAQ (Smith, 1988) notes that "direct genetic evidence of biologically meaningful differentiation among putative host races has been lacking."
114 This paper found that there may be genetic differences pertaining to timing that wild flies emerge, which may be "fine-tuned to coincide closely with fruit maturation."115 However, this paper notes that such differences "do not even signify the existence of a reproductive barrier among populations" and the fly populations on various types of trees "could still represent a single panmictic population,"116 where all individuals can interbreed. It also acknowledges that "the specific genetic nature of the developmental trait investigated here awaits elucidation,"117 so it’s not clear what degree of genetic change has occurred. At the very least, Smith (1988) shows that developmental timing may have changed so that flies emerge when fruit matures, but reproductive isolation does not exist as a result of this small-scale change.

Indeed, another paper cited by the FAQ (Feder
et al., 1988) called the populations mere "races" of the same species because they are "partially reproductively isolated."118 This paper did find 31

differences in frequencies for six alleles in apple and hawthorn fly populations, but it also noted that these were not the result of an inability to hybridize leading to postmating isolation, stating: "Hawthorn and apple flies readily mate in the laboratory and produce viable F
1 progeny."119 The paper further notes that "the likelihood of reproductive incompatibility between these flies is remote."120 Thus, whatever genetic differences do exist, they are insufficient to produce anything less than viable offspring between the populations.

Because fertile hybrids are readily produced, Feder
et al. (1988) proposes that any restriction in gene flow between the two groups is the result of premating factors. But the paper finds that any isolation that does exist is not sufficient to warrant calling the populations different species: "We consequently believe that it is inappropriate to state definitively that hawthorn and apple races represent ‘incipient’ species.’"121 Yet this is the example which the speciation FAQ author called "very exciting."

The FAQ states that "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." At present what we know is this: there is only partial reproductive isolation, and the populations readily produce viable offspring, indicating that only limited biological change has emerged. If this is "very exciting" then the evidence for speciation must be limited indeed.

In fact, it’s important to note that some have suggested that we’re in fact not even witnessing the origin of a new species. Another paper cited by the FAQ (Barton
et al. 1988) states:

"Evolutionary biology is often an attempt to reconstruct history: even for the recent past this is always difficult. In Rhagoletis, for example, it is hard to be certain that the apple race is not an existing sibling species which became common only after it invaded apples."
122

Though this is an interesting example, in the final analysis it does not demonstrate the evolution of complete reproductive isolation, nor does it show significant biological change has evolved.


Response to Section 5.5.2, "Gall Former Fly (Eurosta solidaginis)"


Summary: Populations of the gall former fly live on different species of host plants, leading some to wonder whether they have formed different species. The evidence shows the flies are mere "races" which only have "partial reproductive isolation," and thus are not members of separate species since "both the genetic data … and the behavioral data presented here suggest that there is gene flow between populations." The most significant differences amount to "a preference for mating on the host plant and different emergence times," which correspond to the host plant life cycle. Complete reproductive isolation is not established, and only small-scale biological is observed.



This example discussed by the FAQ studied flies of the species
Eurosta solidaginis that reproduce in host plants of different species. (The host plants are of the same genus; they are 32

Solidago altissima

and Solidago gigantea.) One paper cited (Waring et al., 1990) studied 21 genetic loci and found that six showed variation between fly populations on S. altissima and S. gigantea, and it suggests that the cause is "limited gene flow."123 The likely cause of isolation is plant host choice, as those flies which were found on S. altissima preferred S. altissima in lab experiments, and those flies which were found on S. gigantea preferred S. gigantea in the same.

Another paper cited in this section by the FAQ (Craig
et al. 1993) notes that a "host race is defined as ‘a population of a species that is partially reproductively isolated from other conspecific populations as a direct consequence of adaptation to a specific host.’"124 It cites a definition which defines host race as populations that are "restricted solely or primarily because of different host preference."125 The paper found that this example fits these definitions. Thus, it’s noteworthy that these populations entail mere "races"—not separate species—where there is only "partial reproductive isolation" between the races, which "is maintained only through association with the host plant."126

To be more specific, the partial reproductive isolation between the populations is thought to be "maintained by a combination of a preference for mating on the host plant and different emergence times."
127 But those premating isolation mechanisms do not imply that the populations cannot or do not interbreed. In a breeding experiment without host plants, "38% of the matings took place between host-associated populations" and thus "[v]ery weak assortative mating exists in the absence of host plants."128 Even in the wild complete reproductive isolation does not exist, since "both the genetic data … and the behavioral data presented here suggest that there is gene flow between populations."129

Finally, it is noteworthy that the paper reported "crosses between the
gigantea and altissima fly populations produce viable and fertile offspring."130 Thus, significant change has not emerged between these populations.

Given that the populations are "incompletely reproductively isolated" and that viable and fertile hybrid offspring can be produced, it seems that once again, complete reproductive isolation is not observed and only low levels of biological change have evolved.


Response to Section 5.6, Flour Beetles (Tribolium castaneum)


Summary: Experiments which selected for high, and low weights within flour beetles managed to increase the mean weight in various lines by about a milligram. This is not significant biological change. Some assortative mating was found but reproductive isolation was not complete.



This study cited by the FAQ (Halliburton and Gall, 1981) took a collection of flour beetles, divided them into 4 lines, and in each line selected for those with the heaviest, and lightest weight at the pupal stage over the course of successive generations. At the beginning of the experiment, mean weight of the lines was a little over 2 milligrams. By the end, the mean weight of all groups had increased; the group with the largest increase saw a mean weight of about 3 mg. They thus report "selection for high pupa weight was more effective than selection for low pupa weight."
131 As far as morphological change goes, a 1 mg increase in mean weight of the 33

pupae was the most that was observed; there are apparently impediments to significantly decreasing the weight of these pupae. The most this experiment achieved was to select beetles of slightly differing weights.

Two lines did not show any change in mating preferences, while two showed assortative mating, leading to a lack of "intermediate" pupa weights.
132 This however was not due to inviability of hybrids, but due to mate choice: "Clearly, the offspring of heterogamic matings did survive at least as well as the offspring of homogamic matings, and were intermediate in weight. Any deficiency of intermediate weight pupae must, therefore, be due to a deficiency of heterogamic matings."133 In the lines that showed assortative mating, reproductive isolation was incomplete. Indeed, such changes in body size alongside changes in mating preferences are nothing new as another paper cited by the FAQ (Schluter and Nagel, 1995) states that various studies show "size is important in premating isolation."134

These results are consistent with those of many other studies discussed by the FAQ: complete reproductive isolation was not established, and meager biological change was observed.


Response to Section 5.7, "Speciation in a Lab Rat Worm, Nereis acuminata"


Summary: Initially the investigators thought they had discovered a completely reproductively isolated population of polychaete worms that had been subjected to phases of bottlenecks and population growth in the lab. However, a later study found that these conclusions were wrong, since "the Lab population was already a species different from P1 and P2 at the time when it was originally sampled in 1964." Thus, what happened was the investigators sampled a naturally occurring independent species of polychaete worms and mistakenly concluded that a new species had formed in the lab. The original paper which originally reported this example stated: "the entire process of speciation has rarely been observed." This paper did not remedy that problem.



The FAQ cites a paper (Weinberg
et al., 1992) which purports to have discovered the establishment of complete reproductive isolation among animals—i.e., speciation under the biological species definition. As this section of our response will discuss, while initially they felt confident they had found evidence of speciation in the laboratory, later evidence overturned this claim.

Three populations of polychaete worms of the species
Nereis acuminata were collected from the coastline around the Long Beach, California area. One population ("Lab") went through "two bottlenecks, each followed by exponential population growth." The other two populations (P1 and P2) were collected directly from the field and crossed with the Lab population. While P1 and P2 could produce viable offspring when crossed, crosses between Lab and P1, and Lab and P2, could not. Some premating isolation between Lab and P1/P2 due to mating preferences was also found. They suggest that a difference in chromosome 9 between Lab and P1/P2 might be responsible for the death of hybrids. Thus, the populations are so similar that they can produce offspring, but those offspring are not viable. However, they are not exactly yet sure why the populations are reproductively isolated: 34

"In particular, we can not say whether the alleged speciation, reported here, resulted from selection in the novel laboratory environment (adaptive radiation) or from a stochastic process such as genetic drift or founder effect … Testing these competing hypotheses and determining the genetic basis of each form of reproductive isolation represent difficult challenges for the future."
135

In any case, in this one instance it is claimed that they found establishment of complete reproductive isolation. But as the notable evolutionary biologist Theodosius Dobzhansky (1972) reminds us, "Reproductive isolation evidently can arise with little or no morphological differentiation."
136 That seems to be the case here as the paper reports no morphological change between the populations. Perhaps some slight change in the karyotype of the Lab population is responsible for the reproductive isolation, but no apparent morphological change was reported.

There’s a very important epilogue to this story, however. Four years later, in 1996, the lead author of the original study co-published a follow-up study which essentially retracted and refuted claims of speciation in the lab. The follow-up paper states:

"A critical assumption in Weinberg's experiment is that the P1 and P2 populations are, in fact, representatives of the natural population from which the Lab population hypothetically had diverged and speciated in the laboratory. We have tested this hypothesis by assaying 18 electrophoretic gene loci in the Lab, P1 and P2 populations and in an Atlantic population of a different species, used as a reference control. If the Lab population had speciated from P1 or P2, we would expect that randomly selected electrophoretic markers should be largely similar between the Lab and P1 or P2 populations. However, no common alleles between Lab and P1 or P2 are found in 13 (725) loci, and at two more loci the alleles fixed in Lab are at low frequencies in P1 and P2. The genetic distances between Lab and P1 or P2, are 1.75 ± 0.51 and 1.76 ± 0.52, larger than between most pairs of congeneric species in many sorts of organisms; and roughly similar to the distance between P1 or P2 and the reference population from the Atlantic (D=1.36 ±0.40). The Lab population is genetically depauperate, most likely as a consequence of the founder event, but this reduced variability contributes only trivially (about 1%) to the genetic differentiation between the populations.
We conclude that the Lab population was already a species different from P1 and P2 at the time when it was originally sampled in 1964."137

Thus, this is not an example of speciation in the laboratory, but the original investigation had simply sampled two naturally occurring separate species. Unfortunately the Speciation FAQ has not been updated to accommodate these findings, reported 15 years ago in 1996.

The initial Weinberg
et al. (1992) paper which originally reported this alleged example of speciation stated: "the entire process of speciation has rarely been observed."138 This example did not remedy that problem. 35

Response to Section 5.9.2, "Morphological Changes in Bacteria"


Summary: The FAQ claimed bacteria "underwent major morphological change" but the technical paper it cites does not claim the change was "major." The change entailed a growth in bacterial cell size—from about 1.5 m in length to up to 20 m—which allowed larger bacteria to escape predation. However, the change also involved a fitness cost, where the bigger bacteria faced "a selective disadvantage" when competing with smaller cells in a predator-free environment. Fitness costs in bacteria often limit the ability of new forms to persist, or evolve further. The investigators never claim that a new species of bacteria has evolved. This probably represents the most significant example morphological change reported in the FAQ, but it was in bacteria which are known to vary widely in response to selective pressures, and the change involved a significant fitness cost. After this study was published, the British bacteriologist Alan Linton stated: "Throughout 150 years of the science of bacteriology, there is no evidence that one species of bacteria has changed into another."
139 This study does not claim to contradict Linton’s conclusion.

In this instance, the FAQ claims that a bacterium "underwent a major morphological change when grown in the presence of a ciliate predator." The change was that the bacteria got longer: Normally this species grows as rods of about 1.5 m in length (type S), but they observed cells of various sizes up to 20 m in length (type L) after an apparent selective response to escape predation. The paper cited by the FAQ (Shikano
et al., 1990) do not claim the change is "major."

Bacteria of many sizes and shapes are known, and bacteria are well-known to evolve resistance to selective pressures. However, resistance to a selective agent often involves a fitness cost. In this case, the changes also involved a significant fitness cost. As (Shikano
et al., 1990) reports:

"The type L population was at a selective disadvantage in predator-free competition with type S or the parental strains."
140

A paper published in
Environmental Toxicology and Chemistry observed that "[t]he topic of fitness costs is a central theme in evolutionary biology" because "fitness costs constrain the evolution of resistance to environmental stress."141 Thus, the observed fitness costs could place constraints on the ability of the type-L cells to persist, or evolve further.

Since bacteria reproduce asexually it is difficult to define what constitutes a "species" within bacteria, and whether this should be considered a new "species." Konstantinidis
et al. (2006) suggest that strains with 95% average nucleotide identity (ANI) should be considered part of the same species. The paper cited by the FAQ (Shikano et al., 1990) does not elucidate the genetic basis for the change, and there may be no other changes in the bacterium apart from its change in size. While Shikano et al. (1990) does not explore the ANI between the two types, it would seem likely that they would meet this definition of "species." In any case, it is significant that Shikano et al., 1990 never makes any intimation that a new species of bacteria has evolved.

It’s noteworthy that this probably represents the most significant example of morphological change reported in the entire FAQ, but it was in bacteria which are known to vary widely in 36


response to selective pressures, and the change involved a significant fitness cost. In 2001, over ten years after this study was published, the British bacteriologist Alan Linton stated: "Throughout 150 years of the science of bacteriology, there is no evidence that one species of bacteria has changed into another."
142 Shikano et al. (1990) does not claim to contradict Linton’s conclusion.

PART IV: DOES THE EVIDENCE FOR SPECIATION

COME FROM NATURE OR GROUPTHINK?

The FAQ claims "the biological community considers [speciation] a settled question. Many researchers feel that there are already ample reports in the literature." But this is contradicted by the very literature cited by the FAQ:

 For example one paper cited by the FAQ (Weinberg
et al., 1992) admits that "the entire process of speciation has rarely been observed."143

 Another paper cited by the FAQ (Thoday and Gibson, 1962) states: "Though speciation is one of the more striking features of evolution, direct experimental evidence concerning the origin of species is limited."144

 Yet another paper cited by the FAQ (Dobzhansky and Pavlovsky, 1971) provides the striking admission that: "we are in a situation today similar to that experienced by Darwin more than a century ago: differentiation of species is inferred from copious indirect evidence, but has not actually been observed."145

Again, my purpose has never been to deny that speciation can occur in nature, especially when speciation is defined by the trivial definition of a mere reproductively isolated population. Rather, my purpose is to test the FAQ’s claims.
In that regard, if the FAQ is correct that "Many researchers feel that there are already ample reports in the literature," then the quotes above, and this analysis as a whole, suggest those researchers are wrong.

Perhaps this is an instance where many Darwinian biologists take speciation on faith, an assumption which needs no proof;
someone else has explained speciation. Ironically, the FAQ’s author reports an informal survey which seems to document such groupthink regarding the evidence for speciation:

"I asked about two dozen graduate students and faculty members in the department where I'm a student whether there were examples where speciation had been observed in the literature. Everyone said that they were sure that there were. Next I asked them for citings or descriptions. Only eight of the people I talked to could give an example, only three could give more than one. But everyone was sure that there were papers in the literature."

In other words, "everyone was sure" that the literature contained documented examples of speciation, but only 1/3 could provide an example of such, and only 1/8 could provide more than one example. 37


Presumably the references provided by these graduate students and faculty members provided the basis for many of the references in the FAQ which, as we have seen, almost entirely fail to document speciation.

In his book
The Politically Incorrect Guide to Darwinism and Intelligent Design, Jonathan Wells also analyzed some of the examples in the FAQ. His analysis states:

"Anyone who takes the time to plow through the references cited in these essays finds that most of the alleged instances of ‘observed’ speciation are actually analyses of already existing species that are used to defend one or another hypothesis of how speciation occurs."
146

After taking that time and plowing through the references, I believe that Dr. Wells is correct. As we have seen, at most only "reproductive isolation" was observed—but that is
very different from observing significant biological change. In fact, in most instances: (1) complete reproductive isolation was not even observed so the examples fail to meet the biological species concept definition of "species." And (2) even when reproductive isolation was observed, only very small amounts of biological change were observed, trivializing the importance of the example.

Those examples which fit into category (2) show that the claims of "speciation" often sound impressive, but in reality evolutionists are hiding behind impressive-sounding terminology in order to make it sound like significant biological change has evolved, when in reality virtually nothing of interest happened.


PART V: CONCLUSION

The TalkOrigins "Observed Instances of Speciation" FAQ claims it "discusses several instances where speciation has been observed." After scrutinizing much of the technical literature cited by the FAQ, however, we see claims of mere "incipient" speciation, where reproductive isolation is "initiated" but only "weak" or "partial" and "not complete," or merely "the first step of one possible route to" speciation. Moreover:

 In plant hybridization studies, there was only one example where a new viable species was demonstrated (Section 5.1.1.5). This species does not show significant morphological change from its parent species. Moreover, speciation by hybridization and polyploidy is not a viable mechanism for the vast majority of evolution because: (1) it occurs only within flowering plants, (2) it does not produce new morphological characteristics, and (3) polyploid hybrids cannot arise without pre-existing parent species, meaning it entails a collapse—not gain—of existing diversity. This cannot be a major mechanism in animal speciation.


In all of the other examples analyzed, there was not a single example found where complete reproductive isolation, and thus speciation, was demonstrated. There were also no examples of significant morphological change.

38

1 See http://www.talkorigins.org/faqs/faq-speciation.html (downloaded July 27, 2011).

2 This response responds to as many examples in the FAQ as possible where the original papers cited in the FAQ could be downloaded at a local university library. Some of the examples cited in the FAQ refer to very old papers that were not easily accessible. This rebuttal thus responds to 21 out of 30 total sections in the FAQ.

3
Diane M.B. Dodd, "Reproductive Isolation as a Consequence of Adaptive Divergence in Drosophila pseudoobscura," Evolution, Vol. 43 (6): 1308-1311 (September, 1989).

4
Dolph Schluter and Laura M. Nagel, "Parallel Speciation by Natural Selection," The American Naturalist, Vol. 146 (2):292-301 (August, 1995).

5
Theodosius Dobzhansky, "Species of Drosophila," Science, Vol. 177 (4050):664-669 (August 25, 1972).

6
William R. Rice and Ellen E. Hostert, "Laboratory Experiments on Speciation: What Have We Learned in 40 Years?," Evolution, Vol. 47 (6):1637-1653 (December, 1993).

7
Alan Linton, "Scant search for the maker," Times Higher Education Supplement (April 20, 2001):29.

8
Marion Ownbey, "Natural Hybridization and Amphiploidy in the Genus Tragopogon," American Journal of Botany, Vol. 37 (7):487-499 (July, 1950).

9
Marion Ownbey, "Natural Hybridization and Amphiploidy in the Genus Tragopogon," American Journal of Botany, Vol. 37 (7):487-499 (July, 1950).

10
Indeed, Soltis and Soltis (1989) acknowledge that "Previous morphological, cytological, and electrophoretic analyses indicated that T. mirusa rose independently at least three times." Douglas E. Soltis and Pamela S. Soltis, "Allopolyploid Speciation in Tragopogon: Insights from Chloroplast DNA," American Journal of Botany, Vol. 76 (8):1119-1124 (August, 1989).

11
Jennifer A. Tate, Douglas E. Soltis, and Pamela S. Soltis, "Polyploidy in Plants," p 395 in The Evolution of the Genome (T. Ryan Gregory ed., Elsevier Academic Press, 2005).

12
Arne Müntzing, "Cyto-genetic Investigation on Synthetic Galeopsis tetrahit," Hereditas, Vol. 16:105-154 (1932).

13
Jonathan Wells, The Politically Incorrect Guide to Darwinism and Intelligent Design, p. 53 (Regnery, 2006) (emphasis added) (quoting Douglas J. Futuyma, Evolution, p. 398 (Sinauer Associates, 2005)).

14
Jonathan Wells, The Politically Incorrect Guide to Darwinism and Intelligent Design, p. 53 (Regnery, 2006).

15
Theodosius Dobzhansky and Olga Pavlovsky, "Experimentally Created Incipient Species of Drosophila," Nature, Vol. 230:289-292 (April 2, 1971).

This study has thus arrived at similar results as the assessment by Jonathan Wells in his book The Politically Incorrect Guide to Darwinism and Intelligent Design:

"So except for polyploidy in plants, which is not what Darwin’s theory needs, there are no observed instances of the origin of species. As evolutionary biologists Lynn Margulis and Dorion Sagan wrote in 2002: ‘Speciation, whether in the remote Galápagos, in the laboratory cages of the drosophilosophers, or in the crowded sediments of the paleontologists, still has never been directly traced.’ Evolution’s smoking gun is still missing."
147

The TalkOrigins "Speciation FAQ" gives no evidence that anything has changed significantly since Dobzhansky stated that "we are in a situation today similar to that experienced by Darwin more than a century ago: differentiation of species is inferred from copious indirect evidence, but has not actually been observed."
148 Those who believe that this FAQ provides evidence for significant morphological change or even speciation (e.g., complete reproductive isolation) have been badly misled.