Speciation?

The accompanying is a reproduction of the discovery institute's article

Specious Speciation:

The Myth of Observed Large-Scale

Evolutionary Change


A Response to TalkOrigins’

"Observed Instances of Speciation" FAQ


(Updated Sept. 9, 2013)


by Casey Luskin


Casey Luskin is Research Coordinator at the Center for Science and Culture at Discovery Institute. He holds both a B.S. and M.S. in Earth Sciences from the University of California, San Diego and has conducted geological research at the Scripps Institution for Oceanography. He is also a licensed attorney.



PART I: EXECUTIVE SUMMARY

The TalkOrigins Speciation FAQ, titled "Observed Instances of Speciation"
1 (herein "FAQ"), claims it "discusses several instances where speciation has been observed." For years, this FAQ has been cited by pro-Darwin internet debaters as allegedly demonstrating that neo-Darwinian evolution is capable of producing significant biological change. However, an analysis of the technical literature regarding many of the examples discussed in the FAQ2 reveals that such claims are clearly incorrect. This assessment finds:


NOT ONE of the examples demonstrates the origin of large-scale biological change.

 The vast majority of the examples do NOT even show the production of new species, where a "species" is defined according to the standard definition of a "reproductively isolated population." Only one single example shows the production of a new species of plants via hybridization and polyploidy, but this example does not entail significant biological change.

 Only one of the examples purports to document the production of a reproductively isolated population of animals—
however this example is overturned by a later study not mentioned in the FAQ.

2


　

 Thus, not a single bona fide example of speciation in animals—e.g., the establishment of a completely reproductively isolated population—is given in the FAQ.

I should note from the outset that my purpose is not to deny that speciation can occur in nature, especially when speciation is defined merely as a reproductively isolated population. When trying to assess the creative power of the Darwinian mechanism, that definition is trivial. 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 [of speciation] in the literature," then an analysis of the literature cited in the FAQ suggests those researchers are wrong.


While most of the FAQ’s discussions of the papers it cites are reasonably accurate, these papers amount to citation bluffs if one is claiming to "discus[s] several instances where speciation has been observed." People who believe this FAQ demonstrates that Darwinian processes can produce large-scale biological change have been badly misled. The examples in the FAQ are ultimately used to make inaccurate claims, and the FAQ’s title, "Observed Instances of Speciation," is unwarranted.

PART II: "SPECIATION?" IT’S ALL IN THE DEFINITION.

The TalkOrigins "Observed Instances of Speciation" FAQ, claims to discuss "several instances where speciation has been observed." The most important question is whether these examples show significant biological change has occurred. But this analysis shows:


(1) As a primary finding, none of the examples demonstrate that Darwinian evolution is capable of causing large-scale evolutionary change.

 (2) As a secondary finding, the vast majority of the examples do not even meet the standard definition of "speciation."

To understand why both (1) and (2) are the case, we first need to understand the implications of how evolutionary biologists typically define "species."

Evolutionary biologists typically define "species" as a reproductively isolated population of individuals. For example, the FAQ quotes the great neo-Darwinian evolutionary biologist Ernst Mayr defining a species as "groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups." This classical definition is called the biological species concept. Under this standard definition, speciation entails the origin of such a reproductively isolated population. But does it entail anything else?

Not necessarily. Such definitions say nothing about the degree of morphological, behavioral, or genetic change that has evolved. Thus,
such a definition of "species" does not necessarily imply that significant biological change has taken place between the two populations. In many cases, two populations may be termed different "species" under the biological species concept, but yet the differences between the populations are small-scale and trivial. Indeed: 3

　

 One of the papers cited by the FAQ (Dodd, 1989) clearly states that speciation is reduced to mere reproductive isolation, "According to the biological species concept, speciation is basically a problem of reproductive isolation."3 Another paper (Schluter and Nagel, 1995) cited by the FAQ notes that under this definition species are "defined by the criterion of reproductive isolation rather than morphological criteria."4

 Yet even the notable evolutionary biologist Theodosius Dobzhansky (1972) admits that under this view, "speciation may occur without rearrangement of the genetic materials in the chromosomes" and "Reproductive isolation evidently can arise with little or no morphological differentiation."5

 Putting these quotes, claims, and definitions together, papers cited by the FAQ admit that under the biological species concept, "speciation" does not require any morphological change.

As noted, the FAQ is often cited to explicitly or implicitly claim that Darwinian evolution is capable of producing significant biological change. But the FAQ’s definition of "speciation" seems contrived when used to demonstrate the grander claims of Darwinian evolution that fundamentally new biological structures, body plans, and higher taxa can evolve. Even if we do find reproductively isolated populations that document "speciation," that might provide virtually no evidence that Darwinian processes can produce new complex biological features or large-scale change.
Indeed, the primary finding of this analysis is that the examples in the FAQ do not report the kind of change which shows Darwinian processes can produce fundamentally new types of organisms, new complex biological structures, or higher taxa.

What is more, the vast majority of the examples in the FAQ don’t even document "speciation" under the biological species concept. One paper cited by the FAQ (Rice and Hostert, 1993) notes that "Once pre- and/or postzygotic isolation is complete, speciation has occurred."
6 But in the vast majority of the instances cited by the FAQ, pre- or postzygotic isolation was not complete, and thus speciation did not occur. Thus, a secondary finding of this report is that only one single paper analyzed in the entire FAQ actually reported complete reproductive isolation, and thus "speciation" under the biological species concept.

This raises an irony: the title of the FAQ is "Observed Instances of Speciation," yet the vast majority of the examples analyzed show that complete reproductive isolation was not achieved. Thus, the FAQ is overselling the evidence, not just for significant morphological change, but also for true speciation (e.g., complete reproductive isolation).
If these are some of the best examples for "speciation" that evolutionists can muster, then the evidence for Darwinian evolution must be meager indeed.

Before discussing this analysis of the FAQ, I must again reiterate that 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. 4


PART III: ANALYZING THE FAQ

Section 5.0 of the FAQ purports to provide "examples of observations of speciation," making this the section that needs to be studied to confirm if the evidence backs the FAQ’s claims.

Many of the references cited by the FAQ are old and were difficult to obtain. I downloaded whatever papers I could find online from my local university library and analyzed those examples.


A. Summary of Findings

The following table summarizes the findings of this review for the examples analyzed: FAQ Section:	Summary:
5.1.1.3, "Tragopogon"	Two plant species could hybridize into populations showing small-scale changes compared to the "parent species"—the greatest of which is color changes of the kind well known within plants. Since hybrids are "extremely sterile," it does not seem that speciation has occurred.
5.1.1.5 "Hemp Nettle (Galeopsis tetrahit)"	Two highly similar species of flowering plants within the same genus were crossed in the laboratory to produce a polyploid plant virtually identical to a known species in nature. This confirms the long-known fact that plants can hybridize to form new polyploid forms. But speciation by polyploidy does not produce new morphological characteristics, and the tetraploid daughter species showed only small-scale changes—the greatest of which is color changes of the kind well known within plants—from the parent species. 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.
5.1.1.8, "Maidenhair Fern (Adiantum pedatum)"	An abnormal sporophyte ultimately led to tetraploid, rather than normal diploid sporophytes in a species of fern. No morphological change was reported and tetraploid sporophytes were "less vigorous" than normal. At best this evidence only "provided the opportunity to characterize the first step of one possible route to polyploid formation" as speciation was merely "incipient." Complete speciation was not observed and large-scale morphological change was not observed.
5.1.2, "Animals"	While hybrids can occasionally occur between very closely related animal species, generally speaking animal hybrids are "rare organisms" because hybridization is not a viable