Laboratory Speciation in Helianthus Evolves a Native Species

DNA examination of five species of Helianthus (H. annuus, H. petiolarus fallax, H. anomalus, H. paradoxus, and H. deserticola) suggested that H. annuus and H. petiolarus fallax are the evolutionary parents of the other three species (Rieseberg 1993, 1995, 1993). All five species are self-incompatible and fertile. Typically, H. annuus (the ancestor of the commercial sunflower) and H. petiolarus fallax form hybrids that are almost fully sterile. However, the few fertile hybrids, when subjected to sib-matings and back crossing regimes yield a new species that is fully fertile and cannot cross with either of the parental species. This new species is virtually identical to H. anomalus. The produced species is genetically isolated from the parents by chromosomal barriers. "Under laboratory conditions these changes are repeatable across independent experiments" (Niklas, p.64). The laboratory derived H. anomalus readily crosses with the native H. anomalus. Results indicate that H. deserticola and H. paradoxus may also have arisen via hybridization of H. annuus and H. petiolarus fallax. These two species have different synthetic capabilities from the parents and live in sandier and drier soils. Hybrid speciation may be common in plants where hybrids often form (see Gilia sp., Grant, 1966, Stebbins, 1959, Arnold, 1995), but is presumed rare in animals where hybrids are less common (however, see the minnow Gila seminuda, Bellini, 1994). Experiments to confirm the evolutionary parents of H. deserticola and H. paradoxus have not been performed. 1. Based on nuclear and chloroplast DNA analysis results, the Theory of Evolution predicts that H. annuus and H. pertiolarus fallax are evolutionary ancestors of H. anomalus, H. deserticola and H. paradoxus. 2. Hybrids of H. annuus and H. petiolarus fallax subjected to different regimes (at least 3) of back crossing and sib-matings, all converged into a new plant species with "nearly identical gene combinations" (Rieseberg) as the native species H. anomalus. This confirms the natural evolutionary parents of H. anomalus as predicted.

References 1. Arnold, J and S.A. Hodges. 1995. Are Natural Hybrids Fit or Unfit Relative to Their Parents? Trends Ecol. Evol. 10:67-71. 2. Bullini, L. 1994. Origin and Evolution of Animals by Hybrid Animal Species. Trends Ecol. Evol. 9:422-6. 3. Futuyma, D.J. 1998. Evolutionary Biology. 3rd. Edition, Sinauer Associates Inc., Sunderland, MA. 4. Grant, V. 1966. The Origin of a New Species of Gilia in a Hybridization Experiment. Genetics 54:1189-99. 5. Niklas, K.J. 1997. The Evolutionary Biology of Plants. Univ. Chicago Press, Chicago, IL. 6. Rieseberg, L.H. 1995. The Role of Hybridization in Evolution: Old Wine in New Skins. Amer. J. Bot. 82:944-53. 7. Rieseberg, L.H., and N.C. Ellstrand. 1993. What Can Molecular and Morphological Markers Tell Us About Plant Hybridization? Crit. Rev. Plant Sci. 12:213-41. 8. Rieseberg, L.H., B. Sinervo, C.R. Linden, M. Ungerer and D.M. Arias. 1996. Role of Gene Interactions in Hybrid Speciation: Evidence from Ancient and Experimental Hybrids. Science 272:741-44.A

Nice, neat, repeatable and meets all scientific criteria for a definitive experiment.

[Nothing.In.Science.Is.Proven.]

Then this is all 'he said she said'? That is just another dodge. You mean a mathematical proof now. But you'll come back five minutes later and claim it is proven by 'preponderance of the evidence'. Don't play with words. That's what leads in circles.

Dear Mr. Scum: Here's what you're missing:

29+ Evidences for Macroevolution

Scientific Proof?
Copyright © 1999-2003 by Douglas Theobald, Ph.D.

Contents

hat is meant by scientific evidences and scientific proof? In truth, science can never establish "truth" or "fact" in the sense that a scientific statement can be made that is formally beyond question. All scientific statements and concepts are open to reevaluation as new data is acquired and novel technologies emerge. "Proof", then, is solely the realm of logic and mathematics. That said, we often hear "proof" mentioned in a scientific context, and there is a sense in which it denotes "strongly supported by scientific means". Even though one may hear "proof" used like this, it is a careless and inaccurate handling of the term. Consequently, except in reference to mathematics, this is the last time you will read the terms "proof" or "prove" in this article.
Common Sense is Not Science

Though science formally cannot establish absolute truth, it can provide overwhelming evidence in favor of certain ideas. Often these ideas are quite unobvious, and usually they clash with common sense. Common sense tells us that the earth is flat, that the Sun truly rises and sets, that the surface of the Earth is not spinning at over 1000 miles per hour, that bowling balls fall faster than marbles, that particles don't curve around corners like waves around a floating dock, that the continents don't move, and that objects heavier-than-air can't have sustained flight unless they can flap wings. However, science has been used to demonstrate that all these common sense ideas are wrong.
Science Provides Evidence for the Unobservable

The primary function of science is to demonstrate the existence of phenomena that cannot be observed directly. Science is not needed to show us things we can see with our own eyes. Direct observation is not only unnecessary in science; direct observation is in fact usually impossible for things that really matter. For example, the most important discoveries of science can only be inferred via indirect observation, including such things as atoms, electrons, viruses, bacteria, germs, radiowaves, X-rays, ultraviolet light, energy, entropy, enthalpy, solar fusion, genes, protein enzymes, and the DNA double-helix. The round earth was not observed directly by humans until 1961, yet this counterintuitive concept had been considered a scientific fact for over 2000 years. The Copernican hypothesis that the earth orbits the sun has been acknowledged virtually ever since the time of Galileo, though no one has ever observed the process to this day and in spite of the fact that direct observation indicates the very opposite. All of these "invisible" inferences were elucidated using the scientific method. When the term "evidence" is used in this article, it is used strictly in the context of this scientific method.
The Scientific Method: More than Mere Experimentation

What is the scientific method? This is a complex and contentious question, and the field of inquiry known as the philosophy of science is committed to illuminating the nature of the scientific method. Probably the most influential philosopher of science of the 20th century was Sir Karl Popper. Other notables are Thomas Kuhn, Imre Lakatos, Paul Feyerabend, Paul Kitcher, A. F. Chalmers, Wesley Salmon and Bas C. van Fraassen. This is not the place to delve into an explication of the various philosophies represented by these scholars; for more information I refer you to their works and to the discussion presented by John Wilkins in his Evolution and Philosophy FAQ. I personally take an experimentalist and comparative Bayesian view of the scientific method (Salmon 1990; Mayo 1996), and this will come through in how I present the evidence for common descent.
Now, to answer the question "What is the scientific method?" - very simply (and somewhat naively), the scientific method is a program for research which comprises four main steps. In practice these steps follow more of a logical order than a chronological one:

Make observations.
Form a testable, unifying hypothesis to explain these observations.
Deduce predictions from the hypothesis.
Search for confirmations of the predictions;
if the predictions are contradicted by empirical observation, go back to step (2).

Because scientists are constantly making new observations and testing via those observations, the four "steps" are actually practiced concurrently. New observations, although they were not predicted, should be explicable retrospectively by the hypothesis. New information, especially details of some process previously not understood, can impose new limits on the original hypothesis. Therefore, new information, in combination with an old hypothesis, frequently leads to novel predictions that can be tested further.
Examination of the scientific method reveals that science involves much more than naive empiricism. Research that only involves simple observation, repetition, and measurement is not sufficient to count as science. These three techniques are merely part of the process of making observations (#1 in the steps outlined above). Astrologers, wiccans, alchemists, and shamans all observe, repeat, and measure—but they do not practice science. Clearly, what distinguishes science is the way in which observations are interpreted, tested, and used.
The Testable Hypothesis

The defining characteristic of science is the concept of the testable hypothesis. A testable hypothesis must make predictions that can be validated by independent observers. By "testable", we mean the predictions must include examples of what should be observed if the hypothesis is true and of what should not be observed if the hypothesis is true. A hypothesis that can explain all possible observations and data is not testable nor is it scientific. A good scientific hypothesis must rule out some conceivable possibilities, at least in principle. Furthermore, a scientific explanation must make risky predictions—the predictions should be necessary if the theory is correct, and few other theories should make the same necessary predictions. These scientific requirements are the essence of Popperian falsifiability and corroboration.
For instance, the solipsistic hypothesis that the entire universe is actually an elaborate figment of your imagination is not a scientific hypothesis. Solipsism makes no specific or risky predictions, it simply predicts that things will be "as they are". No possible observations could conflict with solipsism, since all observations always may be explained away as simply another detailed creation of your imagination. Many other extreme examples can be thought of, such as the hypothesis that the universe suddenly came into existence in toto five minutes ago, with even our memories of "earlier" events intact. In general, creationist and "intelligent design" conjectures fail scientifically for these same reasons, since both can easily explain all possible biological observations, and since both make no risky, specific predictions.
In contrast, Newton's scientific theory of universal gravitation predicts that the force between two masses should be inversely proportional to the square of the distance between them (otherwise known as the "inverse square law"). In principle, we could take measurements which indicated that the force is actually inversely proportional to the cube of the distance. Such an observation would be inconsistent with the predictions of Newton's universal theory of gravitation, and thus this theory is falsifiable. Anti-evolutionists, such as the "scientific" creationists, are especially fond of Karl Popper and his falsifiability criterion, and they are well known for claiming that evolutionary theory is unscientific because it cannot be falsified. In this article, these accusations are met head on. Each of the evidences given for common descent contains a section providing examples of potential falsifications, i.e. examples of observations that are predicted not to be observed if the theory is correct.
Degrees of Testability: Hypotheses, Theories, Facts

"Testability" is not an either-or concept; some hypotheses are more testable than others. Contrary to some anti-evolutionist claims, not all hypotheses are equally valid scientific "interpretations" of the evidence. Some hypotheses are more successful in terms of the scientific method. Based on the scientific method, a hypothesis that simply and elegantly explains the observed facts, that predicts many previously unobserved phenomena, and that withstands many potential falsifications is considered a valid and useful hypothesis. From a Bayesian perspective and according to Popper's corroboration measure, the best hypothesis available is the one that explains the most facts with the fewest assumptions, the one that makes the most confirmed predictions, and the one that is most open to testing and falsification.
In scientific practice, a superior and well-supported hypothesis will be regarded as a theory. A theory that has withstood the test of time and the collection of new data is about as close as we can get to a scientific fact. An example is the aforementioned notion of a heliocentric solar system. At one time it was a mere hypothesis. Although it is still formally just a well-supported theory, validated by many independent lines of evidence, it is now widely regarded as scientific "fact". Nobody has ever directly observed an electron, stellar fusion, radiowaves, entropy, or the earth circling the Sun, yet these are all scientific facts. As Stephen J. Gould has said, a scientific fact is not "absolute certainty", but simply a theory that has been "confirmed to such a degree that it would be perverse to withhold provisional consent".
Testing Involves a Totality of Evidence and Statistics

The validity of a hypothesis does not stand or fall based on just a few confirmations or contradictions, but on the totality of the evidence. Often, data that initially may seem to be inconsistent with a theory will in fact lead to new important predictions. The history of Newtonian physics gives a clear example. The abnormal movement of Uranus was initially considered a potential falsification of Newton's new theory. However, by claiming the existence of an unseen planet, the anomaly was explained within Newton's paradigm. In general, an explanation for anomalous behavior should be considered ad hoc unless it is independently verifiable. Positing a new, unseen planet might be considered hedging if there were no independent way to detect if a new planet actually existed. Nevertheless, when technology had advanced enough to reliably test the new prediction, the unseen planet was found to be Neptune.
The lesson to be learned is that alternate explanations for "anomalies" should be treated like any other hypotheses: they should be weighed, tested, and either ruled out or confirmed. But a hypothesis should not be considered falsified until thorough testing has produced multiple lines of positive evidence indicating that the hypothesis is truly inconsistent with the empirical data.
A crucial related point is that modern scientific theories are probabalistic. This means that all testing of scientific predictions is carried out in a statistical framework. Probability and statistics pervade modern scientific theories, including thermodynamics (statistical mechanics), geology, quantum mechanics, genetics, and medicine. The mathematics of probability is a discipline that many people find, shall we say, distasteful. However, a working knowledge of statistics is absolutely essential for judging the fit between observed data and the predictions of any theory.

Contents

References

Chalmers, A. F. (1982) What is this thing called Science? Queensland, Australia, University of Queensland Press.
Stephen J. Gould (1981) "Evolution as Fact and Theory." Discover. May issue.
Kuhn, T. (1970) The Structure of Scientific Revolutions.
Lakatos, I. (1974) "Falsification and the Methodology of Scientific Research Progammes." Criticism and the Growth of Knowledge. I. Lakatos and A. Musgrave. Cambridge, Cambridge University Press: 91-196.
Mayo, D. (1996) Error and the Growth of Experimental Knowledge. Chicago, University of Chicago Press.
Popper, K. R. (1968) The Logic of Scientific Discovery. London, Hutchinson.
Salmon, W. (1990) "Rationality and Objectivity in Science, or Tom Kuhn meets Tom Bayes." Scientific Theories. C. W. Savage. Minneapolis, University of Minnesota Press. 14.
von Fraassen, B. C. (1980) The Scientific Image. Oxford, Clarendon Press.

Contents

Divide the difference between the two by that number of generations and see how much water it takes to get that much change in the next generation.

"How much water"...?

You may find 10 or a hundred highly fragmentary fossils that can be made to look more like one or another.

No you can't. Calling the fossil sequences "made to look more like one or another", as if any fossil can be force-fit into any arbitrary hypothetical transitional sequence, is a gross misrepresentation of the high degree of match actually found in the fossils, and a disgusting slur on paleontologists.

But paradoxically, a longer chain creates a bigger problem:

Ah, yes, the old "the better the evidence, the worse the case is for evolution" ploy...

If you can get 100 steps in sequence from one to the other to happen, why doesn't step one happen 100 times over the same period? And step two 99 times.

For the same reason that if you play a 100 hands of poker in a night, you don't get the same hands dealt twice.

That would scatter intermediates all over the spectrum all over time.

It would if your premise were correct, but...

Apparently it isn't that easy to happen.

Only in the sense that it "isn't that easy" to get a *particular* set of hands dealt in poker. And yet, it's not hard to shuffle and deal the cards.

And if it isn't that easy, how do you get 100 of them until the mammals we happen to have today are perfectly adapted to earth and water?

The same way you can get 100 hands of poker in a night -- one after another.

Is today some special time in history?

No.

Why didn't the transitions die out before reproducing?

Some do.

Why are there then so many of them that just happen to turn up?

Because they existed, and left fossil records of their existence.

There is a lot of wishful thinking in the bone chips that are so elegantly reconstructed to "show" evolution.

Actually, "there is a lot of wishful thinking" in the hand-wavings of people who want to deny the clear indications of the evidence.

Does this look like "bone chips" to you?

Many are not such museum quality

And you feel that somehow justifies your mischaracterizering the ones which are, or ignoring the totality of the evidence?

Links on whale evolution

(From Plagiarized Errors and Molecular Genetics)
.
A particularly impressive example of shared retroposons has recently been reported linking cetaceans (whales, dolphins and porpoises) to ruminants and hippopotamuses, and it is instructive to consider this example in some detail. Cetaceans are sea-living animals that bear important similarities to land-living mammals; in particular, the females have mammary glands and nurse their young. Scientists studying mammalian anatomy and physiology have demonstrated greatest similarities between cetaceans and the mammalian group known as artiodactyls (even-toed ungulates) including cows, sheep, camels and pigs. These observations have led to the evolutionist view that whales evolved from a four-legged artiodactyl ancestor that lived on land. Creationists have capitalized on the obvious differences between the familiar artiodactyls and whales, and have ridiculed the idea that whales could have had four-legged land-living ancestors. Creationists who claim that cetaceans did not arise from four-legged land mammals must ignore or somehow dismiss the fossil evidence of apparent whale ancestors looking exactly like one would predict for transitional species between land mammals and whales--with diminutive legs and with ear structures intermediate between those of modern artiodactyls and cetaceans (Nature 368:844,1994; Science 263: 210, 1994). (A discussion of fossil ancestral whale species with references may be found at http://www.talkorigins.org/faqs/faq-transitional/part2b.html#ceta) Creationists must also ignore or dismiss the evidence showing the great similarity between cetacean and artiodactyl gene sequences (Molecular Biology & Evolution 11:357, 1994; ibid 13: 954, 1996; Gatesy et al, Systematic Biology 48:6, 1999).
Recently retroposon evidence has solidified the evolutionary relationship between whales and artiodactyls. Shimamura et al. (Nature 388:666, 1997; Mol Biol Evol 16: 1046, 1999; see also Lum et al., Mol Biol Evol 17:1417, 2000; Nikaido and Okada, Mamm Genome 11:1123, 2000) studied SINE sequences that are highly reduplicated in the DNA of all cetacean species examined. These SINES were also found to be present in the DNA of ruminants (including cows and sheep) but not in DNA of camels and pigs or more distantly related mammals such as horse, elephant, cat, human or kangaroo. These SINES apparently originated in a specific branch of ancestral artiodactyls after this branch diverged from camels, pigs and other mammals, but before the divergence of the lines leading to modern cetaceans, hippopotamus and ruminants. (See Figure 5.) In support of this scenario, Shimamura et al. identified two specific insertions of these SINES in whale DNA (insertions B and C in Figure 5) and showed that in DNA of hippopotamus, cow and sheep these same two sites contained the SINES; but in camel and pig DNA the same sites were "empty" of insertions. More recently, hippopotamus has been identified as the closest living terrestrial relative of cetaceans since hippos and whales share retroposon insertions (illustrated by D and E in Figure 5) that are not found in any other artiodactyls (Nikaido et al, PNAS 96:10261, 1999). The close hippo-whale relationship is consistent with previously reported sequence similarity comparisons (Gatesy, Mol Biol Evol 14:537, 1997) and with recent fossil finds (Gingerich et al., Science 293:2239, 2001; Thewissen et al., Nature 413:277, 2001) that resolve earlier paleontological conflicts with the close whale-hippo relationship. (Some readers have wondered: if ruminants are more closely related to whales than to pigs and camels, why are ruminants anatomically more similar to pigs and camels than they are to whales? Apparently this results from the fact that ruminants, pigs and camels changed relatively little since their last common ancestor, while the cetacean lineage changed dramatically in adapting to an aquatic lifestyle, thereby obliterating many of the features -- like hooves, fur and hind legs -- that are shared between its close ruminant relatives and the more distantly related pigs and camels. This scenario illustrates the fact that the rapid evolutionary development of adaptations to a new niche can occur through key functional mutations, leaving the bulk of the DNA relatively unchanged. The particularly close relationship between whales and hippos is consistent with several shared adaptations to aquatic life, including use of underwater vocalizations for communication and the absence of hair and sebaceous glands.) Thus, retroposon evidence strongly supports the derivation of whales from a common ancestor of hippopotamus and ruminants, consistent with the evolutionary interpretation of fossils and overall DNA sequence similarities. Indeed, the logic of the evidence from shared SINEs is so powerful that SINEs may be the best available characters for deducing species relatedness (Shedlock and Okada, Bioessays 22:148, 2000), even if they are not perfect (Myamoto, Curr. Biology 9:R816, 1999).

Figure 5. Specific SINE insertions can act as "tracers" that illuminate phylogenetic relationships. This figure summarizes some of the data on SINEs found in living artiodactyls and shows how the shared insertions can be interpreted in relation to evolutionary branching. A specific SINE insertion event ("A" in the Figure) apparently occurred in a primitive common ancestor of pigs, ruminants, hippopotamus and cetaceans, since this insertion is present in these modern descendants of that common ancestor; but it is absent in camels, which split off from the other species before this SINE inserted. More recent insertions B and C are present only in ruminants, hippopotamus and cetaceans. Insertions D and E are shared only by hippopotamus and cetaceans, thereby identifying hippopotamus as the closest living relative of cetaceans (at least among the species examined in these studies). SINE insertions F and G occurred in the ruminant lineage after it diverged from the other species; and insertions H and I occurred after divergence of the cetacean lineage.

That's just a quick layman-level overview of *one* of the many ways that whale evolution has been verified. For more technical examinations along several independent lines of evidence, see for example:

SINE Evolution, Missing Data, and the Origin of Whales
Phylogenetic relationships among cetartiodactyls based on insertions of short and long interpersed elements: Hippopotamuses are the closest extant relatives of whales
Evidence from Milk Casein Genes that Cetaceans are Close Relatives of Hippopotamid Artiodactyls
Analyses of mitochondrial genomes strongly support a hippopotamus±whale clade
A new, diminutive Eocene whale from Kachchh (Gujarat, India) and its implications for locomotor evolution of cetaceans
A new Eocene archaeocete (Mammalia, Cetacea) from India and the time of origin of whales
Mysticete (Baleen Whale) Relationships Based upon the Sequence of the Common Cetacean DNA Satellite1
The Mitochondrial Genome of the Sperm Whale and a New Molecular Reference for Estimating Eutherian Divergence Dates
Limbs in whales and limblessness in other vertebrates: mechanisms of evolutionary and developmental transformation and loss
Eocene evolution of whale hearing
Novel Phylogeny of Whales Revisited but Not Revised
Land-to-sea transition in early whales: evolution of Eocene Archaeoceti (Cetacea) in relation to skeletal proportions and locomotion of living semiaquatic mammals
Subordinal artiodactyl relationships in the light of phylogenetic analysis of 12 mitochondrial protein-coding genes
New Morphological Evidence for the Phylogeny of Artiodactyla, Cetacea, and Mesonychidae
Cetacean Systematics
LIKELIHOOD ESTIMATION OF THE TIME OF ORIGIN OF CETACEA AND THE TIME OF DIVERGENCE OF CETACEA AND ARTIODACTYLA
Phylogenetic Relationships of Artiodactyls and Cetaceans as Deduced from the Comparison of Cytochrome b and 12s rRNA Mitochondrial Sequences
Molecular evolution of mammalian ribonucleases

And much, much more.

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.