Bridge of Size

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Cognostic's picture
@Old Man: Someone posted

@Old Man: Someone posted something like this the other day. I found it fascinating and have been reading up. It should answer your question.

"Approximately 32 million adults in the United States can't read, according to the U.S. Department of Education and the National Institute of Literacy. The Organization for Economic Cooperation and Development found that 50 percent of U.S. adults can't read a book written at an eighth-grade level."

Algebe's picture
@Cognostic: Approximately 32

@Cognostic: Approximately 32 million adults in the United States can't read

And there you have the secret of Donald's success. He's distilled his whole political strategy down into a four-letter slogan that can be printed on a hat over the space where Americans used to keep their brains. Even illiterates can pick out a four-letter word if they see it often enough.

Honestly, this makes me weep. I spent my childhood in a very tired England watching America surge ahead in every field of technology. It gave us all hope and excitement to see American jet fighters, rockets, space apes, Alan Shepard, John Glenn, Neil Armstrong... Star Trek reinforced that image of American technological prowess and hope for the future. Now god is turning Americans into dumbed-down illiterate Trump monkeys. What a crime.

Old man shouts at clouds's picture


Yes I think it was FTW. I read it and clicked the links. Very scary indeed. Then we have Ohio allowing religios wrong answers to be marked explained posters like Jo, and the current fantasies.

I despair.

Calilasseia's picture
I'm not playing "science says

I'm not playing "science says" and bowing down to the wishful thinking of other fallible human beings.

But you'll bow down to the wishful thinking of the authors of a pre-scientific mythology. Double standard duly noted.

That "testable natural processes were responsible ( how are natural processes "responsible" for anything ) for all " is a statement of faith based firmly in thin air.

Bollocks. The evidence for testable natural processes being responsible for all manner of entities and phenomena, is available by the supertanker load, in something like five million peer reviewed scientific papers. Many of which contain, wait for it, direct experimental test of the relevant postulates. Perhaps if you read even a small fraction of said literature, you would learn why those of us who paid attention in class, regard scientific postulates as vastly superior to mythological assertion.

What sort of test equipment was set up several billion years ago to observe these natural processes hard at work forming entities and being "responsible " ?

Are you genuinely this stupid, or is this merely more apologetic duplicity, erected to try and hide your manifest ignorance?

First of all, this specious attempt to play the tiresome creationist "where you there" card, can also be thrown right back at you. Were you there to observe the purported "events" asserted to have taken place in mythology? No? Then you're in no place to pull this piece of apologetic duplicity.

Second, in the case of, say, the origin of life, you have heard of chemical reactions, haven't you? Oh wait, the relevant scientists working in the field, postulate that specific chemical reactions were implicated in the origin of life, and in order to test this, they demonstrated that said reactions worked, and under prebiotic conditions.

Third, in the case of many postulates about the past, we don't need to have been there. All we need, is for the requisite interactions to leave behind them sufficiently persistent physical evidence. Which has happened.

Fourth, "faith" isn't based upon evidence, it's nothing more than uncritical acceptance of unsupported assertions. Which is all that mythology fanboys have to offer.

Fifth, good luck with your attachment to the merely asserted "supernatural". We've been waiting for 5,000 years for assorted mythology fanboys to come up with something better than "my mythology says so, therefore it's true", while in the 300 years it's been operating, modern science has asked, and answered, questions you and your ilk were incapable of even fantasising about.

Cognostic's picture
@C. Come on C. We can all

@C. Come on C. We can all read between the lines. "Then you're in no place to pull this piece of apologetic duplicity (OUT OF YOUR ASS!)

You know you wanted to say it!!!

Sheldon's picture

"Evolution must have the incredible umph to show HOW from absolutely nothing (non -existence) everything popped into existence."

Well well, another creatard who doesn't have even the most basic understanding of evolution, and is comparing it to abiogenesis.

Why aren't they embarrassed by such ignorance? I mean they could Google the difference here in a nanosecond. This tired old carnard represents the end of any attempt at erudite discourse, it's like claiming Newtonian theories of gravity are wrong because they don't tell us how the universe came to exist.

It's also impossible to accept these creatards haven't noticed the only scientific facts they reject are the ones that contradict the myths in their chosen superstition.

Dear oh dear...

As always I direct this lunatic to the talkorigins website, and urge him to educate himself at least with the most basic facts. Like what evolution means, and what the scientific theory evidences and explains and of course what it does not.

I also yet again urge him to look up and understand common logical fallacies, like the argumentum ad ignorantiam fallacy that implies here not knowing how life originated validates the unevidenced superstition of creationism.

TheBlindWatchmaker's picture
non-intelligent non-living

non-intelligent non-living objects (molecules, swirling gases ,quarks, nothing at all

Everything is entirely made of sub atomic particles, nothing is immune from this, we are not 'special'.

When you open a door, it is not 'you' opening the door, but an interaction between the above.

Furthermore, if you follow the chain of causality, everything conforms to known laws of nature and physics.
What you propose is the suspension of the aforementioned and if that is the case, you must meet the burden of proof.

Cognostic's picture
TAKE THE QUIZ:https://www


"It turns out you're not stupid at all. In fact, your intelligence is probably above average. Thanks for playing and for being the shining beacon of intelligence that you are."

And my astrology sign is Gemeni, and my birth stone is Tiger-eye, and I have an Ouroboros tattooed on my back and the other around the scar my foreskin left behind. I had a nose piercing but it got ripped out in a bar fight when I lost my three front teeth.

Obviously nothing said in this post is true.

Cognostic's picture
Fucking test is inconsistent

Fucking test is inconsistent as hell. I took it a second time an it gave me this fucking shit ---

"The results are in're stupid. We'd prefer to let you down gently but there's just no other way to say it. But so what, it's not like stupid people can't live wonderful, happy lives. Embrace yourself for what you are and live every day like it could be your last...which it very well could be, considering how moronic you are. Just kidding. Not about the stupid part, but...well, let's not dwell on it. Thanks for playing."

Asshole test ---- DON'T TAKE IT. We alls knou I is smatr.

David Killens's picture


Cognostic's picture
@David: Post 51

@David: Post 51

Calilasseia's picture
Oh, in the meantime, anyone

Oh, in the meantime, anyone who wants to claim that evolution cannot result in speciation events, has to contend with this little list of scientific papers from the speciation literature, along with, of course, several hundred others containing additional evidence for evolutionary generation of speciation events ...

A Model For Divergent Allopatric Speciation Of Polyploid Pteridophytes Resulting From Silencing Of Duplicate-Gene Expression by Charles R.E. Werth and Michael D. Windham, American Naturalist, 137(4): 515-526 (April 1991) - DEVELOPMENT OF A MODEL TO MATCH OBSERVED SPECIATION IN NATURE

A Molecular Reexamination Of Diploid Hybrid Speciation Of Solanum raphanifolium by David M. Spooner, Kenneth. J. Sytsma and James F. Smith, Evolution, 45(3): 757-764 - DOCUMENTATION OF AN OBSERVED SPECIATION EVENT

A Mouse Speciation Gene Encodes A Meiotic Histone H3 Methyltransferase by Ondrej mihola, Zdenek Trachtulec, Cestmir Vlcek, John C. Scimenti and Jiri Forejt, Science, 323: 350-351 (16th January 2009) - DETERMINING THE FUNCTION OF A GENE DIRECTLY IMPLICATED IN SPECIATION AND FAILURE OF INTERFERTILITY BETWEEN DIVERGING POPULATIONS

A Rapidly Evolving MYB-Related Protein Causes Species Isolation In Drosophila by Daniel A. Barbash, Dominic F. Siino, Arron M. Tarone and John Roote, Proceedings of the National Academy of Sciences of the USA, 110(9): 5302-5307 (29th April 2003) - DETERMINING THE BEHAVIOUR OF A GENE DIRECTLY IMPLICATED IN SPECIATION AND FAILURE OF INTERFERTILITY BETWEEN DIVERGING POPULATIONS

A Screen For Recessive Speciation Genes Expressed In The Gametes Of F1 Hybrid Yeast by Duncan Greig, Public Library of Science Genetics, 3(2): e21 (February 2007) - Determining the presence of speciation genes in a primitive eukaryote, and the roles of any genes thus located

Adaptive Divergence And The Evolution Of Reproductive Isolation In The Wild: An Empirical Demonstration Using Introduced Sockeye Salmon by Andrew P. Hendry, Genetics, 112-113: 515-534 (2001) - DIRECT EXPERIMENTAL TEST OF REPRODUCTIVE ISOLATION AND ITS ROLE IN SPECIATION EVENTS

Adaptive Evolution And Explosive Speciation: The Cichlid Fish Model by Thomas D. Kocher, Nature Reviews Genetics, 5: 288-298 (April 2004) - DISCUSSION OF METHODS OF EMPIRICAL DEMONSTRATION OF SPECIATION INCLUDING MOLECULAR ANALYSES

Chromosomal Rearrangements And Speciation by Loren H. Rieseberg, TRENDS In Ecology & Evolution, 16(7): 351-358 (July 2001) - determination of the input that chromosomal rearrangements may have upon speciation evnets

Chromosome Evolution, Phylogeny, And Speciation Of Rock Wallabies by G. B. Sharman, R. L. Close and G. M. Maynes, Australian Journal of Zoology, 37(2-4): 351-363 (1991) - DOCUMENTATION OF OBSERVED SPECIATION IN NATURE

Evidence For Rapid Speciation Following A Founder Event In The Laboratory by James R. Weinberg Victoria R. Starczak and Danielle Jörg, Evolution 46: 1214-1220 (15th January 1992) - EXPERIMENTAL GENERATION OF A SPECIATION EVENT IN THE LABORATORY

Evolutionary Theory And Process Of Active Speciation And Adaptive Radiation In Subterranean Mole Rats, Spalax ehrenbergi Superspecies, In Israel by E. Nevo, Evolutionary Biology, 25: 1-125 - DOCUMENTATION OF OBSERVED SPECIATION IN NATURE

Experimentally Created Incipient Species Of Drosophila by Theodosius Dobzhansky & Olga Pavlovsky, Nature 230: 289 - 292 (2nd April 1971) - EXPERIMENTAL GENERATION OF A SPECIATION EVENT IN THE LABORATORY

Founder-Flush Speciation On Drosophila pseudoobscura: A Large Scale Experiment by Agustí Galiana, Andrés Moya and Francisco J. Alaya, Evolution 47: 432-444 (1993) EXPERIMENTAL GENERATION OF A SPECIATION EVENT IN THE LABORATORY

Gene Duplication And Speciation In Drosophila: Evidence From The Odysseus Locus by Chau-Ti Ting, Shun-Chern Tsaur, Sha Sun, William E. Browne, Yung-Chia Chen, Nipam H. Patel and Chung-I Wu, Proceedings of the National Academy of Sciences of the USA, 101(33): 12232-12235 (17th August 2004) - EMPIRICAL ANALYSIS OF THE ROLE OF A DEFINED SPECIATION GENE AND DUPLICATION THEREOF IN SPECIATION EVENTS

Gene Transfer, Speciation, And The Evolution Of Bacterial Genomes by Jeffrey G. Lawrence, Current Opinion in Microbiology, 2(5): 519-523 (October 1999) - determining the role of horizontal gene transfer in the development of new bacterial serotypes

Genes And Speciation by Chung-I Wu, Journal of Evolutionary Biology, 14: 889-891 (2001) - development of a rigorous theory of reproductive isolation taking into account incomplete interfertility failure events

Hybrid Lethal Systems In The Drosophila melanogaster Species Complex. II. The Zygotic Hybrid Rescue (Zhr) Gene Of Drosophila melanogaster by Kyoichi Sawamura, Masa-Toshi Yamamoto and Takao K. Watanabe, Genetics, 133: 307-313 (February 1993) - EMPIRICAL DETERMINATION OF THE ROLE OF A NAMED SPECIATION GENE IN SPECIFIC LIVING ORGANISMS

Hybridisation And Adaptive Radiation by Ole Seehausen, TRENDS In Ecology & Evolution, 19(4): 198-207 (April 2004) - development of a rigorous theory underpinning hybrid speciation and SPECIFICATION OF EMPIRICAL TESTS OF THAT THEORY

Incipient Speciation By Sexual Isolation in Drosophila: Concurrent Evolution At Multiple Loci by Chau-Ti Ting, Aya Takahashi and Chung-I Wu, Proceedings of the National Academy of Sciences of the USA, 98(12): 6709-6713 (5th June 2001) - EMPIRICAL DEMONSTRATION OF THE EXISTENCE OF GENES GOVERNING MALE MATING SUCCESS AND FEMALE MATING PREFERENCE LEADING TO SEXUAL SELECTION AND SPECIATION

Laboratory Experiments On Speciation: What Have We Learned In 40 Years? by William R. Rice and Ellen E. Hostert, Evolution, 47(6):1637-1653 (December 1993) - review of speciation literature and determination of the validity of reproductive isolation as a speciation mechanism

Models Of Evolution Of Rperoductive Isolation by Masatoshi Nei, Takeo Maruyama and Chung-I Wu, Genetics, 103: 557-559 (March 1983) - DIRECT EMPIRICAL TEST OF MODELS OF REPRODUCTIVE ISOLATION, AND ESTABLISHMENT OF CORRELATION WITH REAL WORLD DATA

Phylogenetics And Speciation by Timothy G. Barraclough and Sean Nee, TRENDS in Ecology & Evolution, 16(7): 391-399 (July 2001) - Determination of rigorous methods for using phylogenetic analyses to establish speciation events

Pollen-Mediated Introgression And Hybrid Speciation In Louisiana Irises by Michael L. Arnold, Cindy M. Buckner and Jonathan J. Robinson, Proceedings of the National Academy of Sciences of the USA, 88(4): 1398-1402 (February 1991) - OBSERVATION OF A SPECIATION EVENT IN NATURE

Premating Isolation Is Determined by Larval Rearing Substrates in Cactophilic Drosophila mojavensis. IV. Correlated Responses In Behavioral Isolation To Artificial Selection On A Life-History Trait by William J. Etges, The American Naturalist, 152(1): 129-144 (July 1998) - DIRECT EMPIRICAL TEST OF BEHAVIOURAL ISOLATION AS A MECHANISM DRIVING SPECIATION

Rapid Evolution Of Postzygotic Reproductive Isolation In Stalk-Eyed Flies by Sarah J. Christianson, John G. Swallow and Gerald S. Wilkinson, Evolution, 59(4): 849-857 (12th January 2005) - DIRECT EMPIRICAL TEST AND MOLECULAR ANALYSIS OF SEXUAL SELECTION AND HYBRID STERILITY AS MECHANISMS DRIVING SPECIATION

Role Of Gene Interactions In Hybrid Speciation: Evidence From Ancient And Experimental Hybrids by Loren H. Rieseberg, Barry Sinervo, C. Randall Linder, Mark C. Ungerer and Dulce M. Arias, Science, 272: 741-745 (3rd May 1996) - DIRECT EXPERIMENTAL TESTS OF HYPOTHESES REGARDING HYBRID SPECIATION

Searching For Speciation Genes by Roger Butlin and Michael G. Ritchie, Nature, 412: 31-33 (5th July 2001) - DIRECT EMPIRICAL SEARCH FOR GENES IMPLICATED IN SPECIATION EVENTS

Selfish Operons And Speciation By Gene Transfer by Jeffrey G. Lawrence, Trends in Microbiology, 5(9): 355-359 (September 1997) - EMPIRICAL DETERMINATION OF MECHANISMS FOR DEVELOPMENT OF NEW BACTERIAL SEROTYPES

Sex-Related Genes, Directional Sexual Selection, And Speciation by Alberto Civetta and Rama S. Singh, Molecular & Biological Evolution, 15(7): 901-909 (1998) - EMPIRICAL DETERMINATION OF THE SHAPING OF GENES IMPLICATED IN SPECIATION VIA SEXUAL SELECTION

Sexual Selection, Reproductive Isolation And The Genic View Of Speciation by J. J. M. Van Alphen and Ole Seehausen, Journal of Evolutionary Biology, 14: 874-875 (2001) - application of known speciation mechanisms to the Lake Victoria superflock of Cichlid fishes

Speciation Along Environmental Gradients by Michael Doebeli and Ulf Dieckmann, Nature, 421: 259-264 (16th January 2003) - determination of the effects of environmental pressures upon the outcome of speciation events

Speciation And The Evolution Of Gamete Recognition Genes: Pattern And Process by S. R. Palumbi, Heredity, 102: 66-76 (2009) - determination of the role of gamete recognition genes in speciation events, and their rapid evolution in segregated populations

Speciation By Hybridisation In Heliconius Butterflies by Jesús Mavárez, Camilo A. Salazar, Eldredge Bermingham, Christian Salcedo, Chris D. Jiggins and Mauricio Linares, Nature, 441: 868-871 (15th June 2006) - DETERMINATION OF A SPECIATION EVENT IN NATURE, FOLLOWED BY LABOARTORY REPRODUCTION OF THAT SPECIATION EVENT, AND CONFIRMATION THAT THE LABORATORY INDIVIDUALS ARE INTERFERTILE WITH THE WILD TYPE INDIVIDUALS

Speciation By Hybridization In Phasmids And Other Insects By Luciano Bullini and Guiseppe Nascetti, Canadian Journal of Zoology 68(8): 1747-1760 (1990) - OBSERVATION OF A SPECIATION EVENT IN NATURE

Speciation By Postzygotic Isolation: Forces, Genes And Molecules by H. Allen Orr and Daven C. Presgraves, Bioessays, 22(12): 1085-1094 (2000) - EMPIRICAL DETERMINATION OF THE EXISTENCE OF SPECIATION GENES AND THEIR ROLE IN INTERFERTILITY FAILURE BETWEEN SEGREGATED POPULATIONS

Speciation Genes by H. Allen Orr, John P. Masly and Daven C. Presgraves, Current Opinion in Genetics & Development, 14: 675-679 (2004) - DETERMINATION OF THE EXISTENCE OF SPECIATION GENES AND THEIR SUSCEPTIBILITY TO DARWINIAN SELECTION

Speciation, Hybrid Zones And Phylogeography - Or Seeing Genes In Space And Time by Godfrey M. Hewitt, Molecular Ecology, 10: 537-549 (2001) - review of origins of speciation theory, current developments, and application to past and present speciation events

Speciation By Habitat Specialisation: The Evolution Of Reproductive Isolation As A Correlated Character by William R. Rice, Evolutionary Ecology, 1: 301-314 (1987) - LINKING OF SPECIATION EVENTS TO NICHE MOBILITY AND ADAPTATION FOR NEW NICHES

The Evolution Of Asymmetry In Sexual Isolation: A Model And Test Case by Stevan J. Arnold, Paul A. Verrell and Stephen G. Tilley, Evolution, 50(3): 1024-1033 (June 1996) - DEVELOPMENT OF AN EXTENDED MODEL OF SEXUAL SELECTION FOLLOWED BY EMPIRICAL TEST OF THAT MODEL AND DETERMINATION OF CORRELATION WITH A REAL WORLD POPULATION DIVERGENCE EVENT

The Evolution Of Reproductive Isolation Through Sexual Conflict by Oliver Y. Martin and David J. Hosken, Nature,423: 979-982 (26th June 2003) - DIRECT EXPERIMENTAL TEST OF SEXUAL CONFLICT AS A DRIVER OF SPECIATION

The Evolutionary Genetics Of Speciation by Jerry A. Coyne and H. Allen Orr, Philosophical Transactions of the Royal Society of London Part B, 353: 287-305 (1998) review of recent advances in speciation theory and empirical results

The Genetic Basis Of Reproductive Isolation: Insights From Drosophila by H. Allen Orr, Proceedings of the National Academy of Sciences of the USA, 102 supplement 1: 6522-6526 (3rd May 2005) - review of work on speciation genes and the empirical determination of their roles

The Genic View Of The Process Of Speciation by Chung-I Wu, Journal of Evolutionary Biology, 14: 851-865 (2001) - review of theory of speciation including renewed insights into Darwin's own early view of the topic, and how this correlates to a hitherto unforeseen extent with modern genetic results

The Gibbons Speciation Mechanism by S. Ramadevon and M. A. B. Deaken, Journal of Theoretical Biology, 145(4): 447-456 (1991) - DEVELOPMENT OF A MODEL ACCOUNTING FOR OBSERVED INSTANCES OF SPECIATION

The Phylogeny Of Closely Related Species As Revealed By The Genealogy Of A Speciation Gene, Odysseus by Chau-Ti Ting, Shun-Chern Tsaur and Chung-I Wu, Proceedings of the National Academy of Sciences of the USA, 97(10): 5313-5316 (9th May 2000) - EXPERIMENTAL VERIFICATION OF A PREDICTION ABOUT SPECIATION MECHANISMS AT THE MOLECULAR LEVEL

The Population Genetics Of Speciation: The Evolution Of Hybrid Incompatibilities by H. Allen Orr, Genetics, 139: 1805-1813 (April 1995) - development of a gene-based model for speciation and the implications of the results obtained from that model for speciation research

The Theory Of Speciation Via The Founder Principle by Alan R. Templeton, Genetics, 94:1011-1038 (April 1980) - development of a model for founder speciation, and DIRECT EXPERIMENTAL TEST of that model by applying it to a real world organism

What Does Drosophila Genetics Tell Us About Speciation? by James Mallet, TRENDS in Ecology & Evolution, 21(7): 386-393 (July 2006) - Comparison of Drosophila data with data from other organisms to produce a more complete picture of speciation mechanics

Indeed, one of the papers I didn't list above, but which is particularly relevant, is one I shall now cover in detail, viz:

Reproductive Isolation As A Consequence Of Adaptive Divergence In Drosophila pseudoobscura by Diane M. B. Dodd, Evolution, 43(6): 1308-1311 (September 1989) [Full paper downloadable from here]

According to the biological species concept, speciation is basically a problem of reproductive isolation. Of the many ways to classify isolating mechanisms, the two main divisions are premating isolation, in which mating is prevented from occurring, and postmating isolation, in which mating takes place but viable, fertile offspring are not produced. There is much debate over which type of mechanism, premating or postmating, is most likely to develop first and how the isolation comes about (e.g., see Dobzhansky, 1970; Mayr, 1963; and Muller, 1949).

In an attempt to gain insight into the process of the development of reproductive isolation, eight populations of Drosophila pseudoobscura were studied. These were first used by Powell and Andjelkovič (1983) in a study of the alpha-amylase (Amy) locus. Four were reared on a starch-based medium, and four were reared on a maltose-based medium. These two media are both quite stressful; it initially took several months for the populations to become fully established and healthy. Considering the pressure placed on the populations by the media, one would expect to see some kind of adaptive divergence between the starch-reared and maltose-reared flies.

Several changes were in fact observed in the eight populations. Powell and Andjelkovič noted an increase in the "fast" allele of Amy in the starch populations as well as an increase in one of the patterns of amylase activity in the midgut. However, no corresponding changes were seen in the maltose populations. Elsewhere (Dodd, 1984), I have presented evidence that the populations have become differentially adapted to the two media. In this study, it is shown that the populations have also developed behavioral isolation as a pleiotropic by-product of this adaptive divergence.

Basically, Dodd's experiment consisted of maintaining populations of flies, subjecting them to different dietary régimes in a manner that would result in adaptations to those régimes appearing, then demonstrating that assortative mating took place amongst the flies - in other words, members of each population exhibited a strong preference for members of their own population as mate choices.

Assortative mating is regarded as a major sign of incipient speciation, because it eliminates gene flow between the populations, thus ensuring that those populations will diverge. Eventually, said divergence will result in a fertility gap arising between the two populations. If we have two such populations, A and B, then individuals from population A can be trial mated to individuals from population B, to determine if interfertility failure has taken place. If it has, then you have a bona fide speciation event. Prior to such tests indicating interfertility failure, what you have, from a rigorous standpoint, is an incipient speciation event - the potential is there, but it hasn't actually been put to the test fully. Dodd only claimed in her paper that assortative mating was observed, but of course, assortative mating is a significant indicator that speciation is taking place, because of its effects upon gene flow.

Let's delve into the paper in more detail, shall we?

Materials And Methods

All eight D. pseudoobscura populations were derived from a single population collected at Bryce Canyon, Utah (see Powell and Andjelkovič [1983] for details on the media and the generation of the populations). The four starch-reared populations were designated Ist- IVst; the maltose-reared populations were designated Ima-IVma. The flies were maintained in population cages at 25°C. The present investigation was begun approximately one year after the populations were started.

Starch-adapted populations were tested against maltose-adapted populations in every possible combination to determine whether adaptation to the two new regimes could have induced the development of ethological isolation. Multiple-choice tests were performed using mating chambers modeled on those described by Elens and Wattiaux (1964). All flies used in the mating-preference tests were reared for one generation on standard cornmeal-molasses-agar medium. Virgin males and females were anesthetized with CO2, isolated from the opposite sex, and aged on standard medium for 3-6 days. Twelve females from each of the populations to be tested were placed in the chamber. Twelve males from the two populations were then introduced as nearly simultaneously as possible. The flies were not anesthetized for this procedure. The tests were performed at room temperature (no higher than 25°C), under bright (but not direct) lighting. The chambers were observed for 60-90 minutes.

Individuals of one population had the tips of their right wings clipped to allow identification. At least two replicates of each test were performed, with the wing clipping alternated between populations. Wing clipping has not been found to interfere with mating success in Drosophila (Ehrman, 1966; Ehrman and Petit, 1968; Powell, 1978; Robertson, 1982; Knoppien, 1984; van den Berg et al., 1984; Dodd and Powell, 1985; Spiess, 1986), and once again in the present tests, wing clipping had no effect on mating propensity in either sex. Of the 1,558 matings scored, 778 were with nonclipped males, and 780 were with clipped males; 793 non-clipped females mated, while 765 clipped females mated. These differences are not statistically significant.

An isolation index (I) was calculated for each mating test. The index used follows Stalker (1942), Bateman (1949), and Merrell (1950), with the standard error derived following Malogolowkin-Cohen et al. (1965):

I = (homogamic matings - heterogamic matings) ÷ total matings(N)

Standard Error (SE) of I = [(1-I^2)/N]^½

I ranges from -1 to 1; a value of zero indicates random mating; I > 0 indicates positive assortative mating; and I < 0 indicates negative assortative mating. Contingency chi-square tests were also performed to check for deviations from random mating.

Basically, the procedure consisted of the following:

[1] Set up several populations of Drosophila pseudoobscura, divided into two groups. One group of populations is raised on a starch-rich medium (these populations are designated in her paper with the postfix "st"), and the other group is raised on a maltose-rich medium (these populations are designated with the postfix "ma").

[2] Keep these populations separate from each other for a number of generations. In Dodd's experiment, approximately 1 year elapsed before the assortative mating tests took place. For this species, 1 year equates to 8 new generations, which might seem to be a surprisingly small number of generations for any such effect to become noticeable: more usually, one would expect something like 30 or 40 generations to be required. One of the interesting features of Dodd's research, which has since been replicated with essentially the same results, is that the experimental results were obtained after just 8 generations of separation. Out of interest, way back in the 1960s, Theodosius Dobzhansky reared a population of the same fly species in isolation from wild-type flies for approximately 5 years, then tested his population for interfertility with the wild type - the paper in question documenting this is the following:

Experimentally Created Incipient Species Of Drosophila by Theodosius Dobzhansky & Olga Pavlovsky, Nature 230: 289 - 292 (2nd April 1971)

Sadly this paper is behind a paywall, so I can't bring it in here (sigh), but the abstract reads thus:

By means of selection in many generations, ethological (sexual) isolation has been built between strains of Drosophila which were formerly not reproductively isolated.

In that experiment, Dobzhansky demonstrated that his laboratory population of Drosophila exhibited interfertility failure with wild type flies - all the males produced by cross matings were sterile. This occurred after just five years of isolation, which would equal approximately 40 generations in the case of Drosophila pseudoobscura.

As a consequence of that prior work, Dodd's research can safely be regarded as having generated an incipient speciation event, because cessation of gene flow between Drosophila populations has been demonstrated to result in rapid divergence between the populations thus genetically isolated, sufficient to result in empirically validated interfertility failure, at which point you have a full-blown speciation event.

Let's return to Dodd's paper, shall we?


The results of the mating-preference tests between starch-adapted and maltose-adapted populations are given in Table 1. Contingency chi-square tests reveal that 11 out of the 16 combinations show significant deviation from expectations based on random mating. The isolation indexes of these crosses all indicate positive assortative mating, ranging from 0.30 ± 0.13 to 0.49 ± 0.10. The crosses that do not show significant departure from random mating also have positive isolation indexes, ranging from 0.18 ± 0.14 to 0.24 ± 0.13. A one-tailed sign test (Champion, 198 1 pp. 276-280) on the indexes shows that the probability of obtaining 16 positive indexes for 16 crosses is less than 0.001.

It is possible that the behavioral isolation apparent between the starch- and maltose-adapted populations is a result of bottlenecks in population size when the populations were first established. Thus, the populations may have diverged due to such founder-flush effects as proposed by Carson (197 1, 1975) and experimentally observed by Powell (1978). If this were the case, there should be isolation between populations within the same regime. Therefore, each starch-adapted population was tested with each other starch-adapted population. Likewise, each maltose-adapted population was tested with each other maltose-adapted population.

Table 2 gives the data for these crosses. None of the within-regime tests deviates significantly from expectations for random mating according to the [chr]967[/chr][sup]2[/sup] tests. The indexes range from -0.06 ± 0.14 to 0.15 ± 0.13 in the starch-regime tests and from -0.21 ± 0.13 to 0.18 ± 0.14 in the maltose-regime tests. Four of the six within-maltose-regime crosses show heterogamic preferences, as do two of the six within-starch-regime crosses. Two-tailed sign tests were again performed to confirm the randomness of the indexes: starch regime: P = 0.688; maltose regime: P = 0.688; all within-regime crosses: P > 0.999.

There is no assortative mating within regimes. Averaging the isolation indices within the three categories illustrates the general pattern: 0.33 for the tests of starch versus maltose, 0.05 for the tests within the starch regime, and -0.01 for the tests within the maltose regime.

So, the following tests were performed:

[1] Establish whether there existed positive assortative mating enforcing genetic separation between the st and ma populations;

[2] Establish whether or not positive assortative mating occurred within the separate st and ma populations as well, in order to eliminate founder-flush effects.

The results were conclusive. Strong positive assortative mating existed between the st and ma populations after only 8 generations. However, no such assortative mating occurred within the st populations or the ma populations.

Dodd's paper concludes with:


Significant behavioral isolation between starch-adapted and maltose-adapted populations was observed. The isolation was not a result of conditioning of the flies to the two media, since all tests were performed using flies that had been reared on a common medium and had experienced neither starch nor maltose. Nor was physical isolation alone responsible for the changes in mating behavior, since there was no evidence of behavioral isolation between any pair of the four starch-adapted populations nor between any pair of the four maltose-adapted populations.

The ethological isolation was a pleiotropic by-product ofthe adaption of the populations to the two media, confirming one of the basic tenets of the Modem Synthesis. Reproductive isolation was not the target of the selection, and there was no a priori reason to believe that adaptation to starch or maltose should have any effect on mating behavior, yet isolation developed.

Similar studies resulting in the development of stable premating isolation due to adaptive divergence have been reported. Kilias et al. (1980) observed behavioral isolation between strains of D. melanogaster reared at different temperatures and relative humidities. Flies from the same base population subjected to different regimes developed reproductive isolation, while flies from different gene pools reared under the same conditions exhibited random mating. Markow (1981) selected for phototactic and geotactic behavior in D. melanogaster. Behavioral isolation was evident between some pairs of the selected and control populations. Soans et al. (1974) and Hurd and Eisenberg (1975) reported reproductive isolation in housefly (Musca domestica) populations selected for positive and negative geotaxis.

The results of this study also demonstrate that reinforcement of premating isolating mechanisms through selection is not necessary for the development of significant levels of behavioral isolation. The isolation observed here developed in complete allopatry. The populations were maintained separately at all times, and thus there was no opportunity for reinforcement through selection against hybrids. The isolation is due solely to the process of adaptation to the novel regimes.

This process led to consistent changes in all four populations under each regime. Each of the four populations subjected to the same regime acquired the same (or similar) changes in mating behavior, such that flies from different populations under the same regime are not isolated. Isolation is only evident between regimes.

The mechanism of the isolation in this system is as yet unknown. Kilias et al. (1980) noted for one of their nine combinations that females adapted to one regime (cool, dry) mated more frequently than females from the second regime (warm, humid). Yet in another case, males reared in the warm, humid regime were more active than the cool-adapted males. Overall, there was no significant difference in sexual activity, as measured by numbers of each type mating, in either sex. Similarly, in this study chi-square tests revealed no significant differences in the numbers of flies from each population involved in matings (Χ²(males) = 4.5, Χ²(females) = 1.8, d.f: = 7). There is no difference in sexual activity between flies from the two regimes. Possible differences in specific courtship behaviors are presently being examined.

I think that covers all the bases you need. Of course, this is one of the reasons why I keep telling people to read the papers for themselves, so that they can see for themselves what is actually being claimed.

In short, Dodd demonstrated that two separated populations, will eventually develop assortative mating preventing gene flow between those populations, and that over time., the divergence in those separated populations will eventually result in interfertility failure between those populations, at which point one has a speciation event in place. This is an experiment that the diligent can perform in an ordinary greenhouse over a three year period, at the end of which, one will have populations diverged to the point of interfertility failure. Which means that you can produce your own speciation event, simply by keeping the relevant populations separated for sufficient time.

Again, game over, methinks.

cranky47's picture
I'm beginning to think

I'm beginning to think Vochensmut is a troll , or possibly a Trump voter.

On the other hand, I guess it is possible for a person to be so engulfed with cognitive dissonance so as to be literally incapable of reason when it comes to personal superstitions.

In the meantime, it's nice to have a nice new chew toy. When everyone is finally sufficiently bored, just ignore it and it will go away

Cognostic's picture
@Calilasseia: RE: Speciation

@Calilasseia: RE: Speciation. I gotta admit, to any normal human being that would seem like a slam ducn, bitch slap into reality. But you gotta remember those creationists have super human mind control and the all powerful God, creator of the universe, on their side. I just worry that it's not enough for them.

(Edit: don't slam your duck, it will die. Dunk it instead.)

Sheldon's picture
The most commonly used

The most commonly used bestselling text for medical practitioners and students on human anatomy, is The Atlas of Human Anatomy by Frank H Netter MD.

Now guess what, it tells us nothing at all about the origin of life. One assumes then this latest creatard troll thinks the book, and the entire medical profession are wrong?

Or is evolution being singled out yet again by another disgruntled creatard, because it contradicts the risible unevidenced creation myth is his bible.


Sheldon's picture
4 pages, and not one piece of

4 pages, and not one piece of objective evidence offered to support the existence of any deity, quelle surprise.


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