Subject: Species and creation Topics: }No new species (alternately, +quot;kinds+quot;) are

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Subject: Species and creation Topics: }No new species (alternately, "kinds") are evolving today. }Slight variation can't turn one kind into another. }Just because two animals LOOK similiar does not mean there is "common ancestor }Mendelian inheritance says that recessive characters reappear }Hybrids are infertile, so a newly evolved individual couldn't breed. }The animals couldn't have distributed themselves all over the globe. }"impossible gulfs" }The failure of some organisms to evolve at all. }No new phyla, classes, or orders have appeared. }The occurrence of parallel evolution, in which similiar structures evolve }Many species have remained absolutely fixed throughout geologic time. }A great many modern species are very evident degenerate }All the great phyla appear quite suddenly in the fossil record. }Selection cannot change the frequency of variants ---------------------------------------------------------------------- }- No new species (alternately, "kinds") are evolving today. "Three species of wildflowers called goatsbeards were introduced to the United States from Europe shortly after the turn of the century. Within a few decades their populaltions expanded and began to encounter one another in the American West. Whenever mixed populations occurred, the specied interbred (hybridizing) producing sterile hybrid offspring. Suddenly, in the late Fourties two new species of goatsbeard appeared near Pullman, Washington. Although the new species were similliar in appearance to the hybrids, they pproduced fertile offspring. The evollutionary proces had created a separate species that could reproduce but not mate with the goatsbeard plants from which it had evolved." The article is on page 22 of the February, 1989 issue of _Scientific_American_. It's called "A Breed Apart." It tells about studies conducted on a fruit fly, Rhagoletis pomonella, that is a parasite of the hawthorn tree and its fruit, which is commonly called the thorn apple. About 150 years ago, some of these flies began infesting apple trees, as well. The flies feed an breed on either apples or thorn apples, but not both. There's enough evidence to convince the scientific investigators that they're witnessing speciation in action. Note that some of the investigators set out to prove that speciation was not happening; the evidence convinced them otherwise. In 1916, a single pair of wallabies escaped from a zoo in Oahu. They survived and bred in the wild, and now there is a whole population. They are smaller and more lightly colored than the Aussie wallabies. They eat Hawaiian plants that are poisonous to the Aussie wallabies, because they evolved a new liver enzyme to detoxify them. They can no longer breed with the Australian wallabies, so they qualify as a new species. Sources: "Instant Evolution", Science Digest, July 1982 Saladin / Gish debate at Auburn University at Montgomery, 24 March 1984 How can you say that no new species have arisen when dozens of previously undiscovered species are found each year in Costa Rica alone? Also, isn't the latest evidence that maize evolved about 4000 years ago? }- Slight variation can't turn one kind into another. "One lion may be fitter } than another lion, but ... all his offspring will still be lions." What is a "kind"? }Just because two animals LOOK similiar does not mean there is "common } ancestory" The interesting point is that, when checked, there IS. Genetic comparisons reveal (objectively) a kinship where it was before predicted on evolutionary grounds. I believe the error rate is less than 1%. What is facinating about the comparisons of the numbers of genes shared between species is that when you draw a genetic tree of what species are related to what, it looks almost identical to the tree drawn by anthropologists who make their tree based on comparisons of morphology (humans look more like chimps than turtles therefore chimps are more closely related). This is the beauty of science that a hypothesis (relatedness of species) is shown by two completely differing mechanisms just as the age of artifacts can be determined by rock layers (those on top are newer) and carbon and other radioactive dating techniques. How is this done? In brief: DNA similarity is measured by mixing fragments of DNA from the two species and measuring the thermal stability of the resulting hybrid molecules, which is proportional to the degree of matching. It can be calibrated by using DNAs of known composition, for example the genomes of completely sequenced viruses. Accuracy is limited by the ability to measure the melting temperature and by the slight difference in stability between A-T base pairs and C-G ones. There has been heavy theoretical debate (ending in an amazing shouting match at a meeting last summer, alas--I was there, and it was embarrasing) about whether the method is accurate enough to resolve the chimp/ human/gorilla trichotomy. DNA similarity does measure overall composition, and two organisms could be very different morphologically while still having high DNA similarity (indeed, chimps and humans are much more dissimilar than most pairs with the same DNA distance). However, overall composition is probably a better guide to relatedness than specific genes, which are likely to be under different selection in humans and chimps. What is the noise, and what is the signal? "Junk" DNA is the most useful for determining phylogeny, because it is more likely to evolve in a gradual time-dependent fashion. Coding and controlling regions are interesting in that they tell us about the differences. }- Mendelian inheritance says that recessive characters reappear, and thus we } should expect humans with characteristics of apes. They do. Tails, for instance. And other "ape" traits that happen to also be "human traits". Like toes, body hair,... This disregards the basic mechenisms of natural selection and genetics. It makes the wrong assumption that ape-like characters are recessive and that all of the traits in the ancestor population are present but usually unexpressed in the supposed descendant population. Neither idea is true. }- Hybrids are infertile, so a newly evolved individual couldn't breed. Hybrids are often not fertile or robust. They may be desirable to man if man amde, but they may not succeed in an evolutionary sense. The premise is incorrect. First, what is meant by "hybrid" is unclear in this context - is it a hybrid only if it is infertile? And even in those cases in which the offspring is usually infertile, that is not always the case. As witnessed the horse and the donkey. }- There exist "impossible gulfs" between animal/vegetable, } invertebrate/vertibrate, marine animals/amphibians, amphibians/reptiles, } reptiles/birds, reptiles/mammals, mammals/humans. } Eight impossible gulfs: Impossible to find gulfs. } 1) Between the living and non-living or dead matter; This is the abiogenesis debate. The rest is a taxinomy of man with the similarity argument turned into the gaps argument. Is the glass half empty or half full? What is this gulf? I have yet (despite looking and asking many) found it at all, let alone found it to be an impossible gulf. The spectrum between clearly living and singular elementary particles is wide, and not linear (few things really are) but it appears to be continuous. }} 2) Between the vegetable and the animal kingdoms; Animal cells have some similarity with plant cells, and indeed there are forms, euglena, with cloroplasts and flagellae, that look like intermediates. Cells from both kingdoms are eukeryots that are distinct from other cell types belonging to at least three other kingdoms. There are quite a few plant/animals in the same creature. Most microscopic because a plant doesn't collect enough energy to be mobile in large scale. But there are plenty of small ones. What is a euglena? And where do protista & viri fit in here? } 3) Between the invertebrates and the vertebrates; The vetebrates are biochemically closest to the echinodermata, and urochordates. The free swimming soft chord animals are similar to the sessile forms. See also sharks and squids. } 4) Between marine animals and amphibians; A steady change from fish to lobefined air breathing fish to amphibians with fish like larval stages can be observed in extant species and in the fossil record. See also mudpuppies and frogs. An amphibian that never leaves the water is a marine animal. This gulf is not only impossible, it is non-existant. } 5) Between amphibians and reptiles; Amphibians predate reptiles in the fossil record. The development of the amneonic egg, with shell and the difference in the skin of extant reptiles and amphibians suggests that the reptilian characters were adaptaions developed on amphibian ancestors. The time in the fossil record when the reptiles became important was one when amphibian habitats were being reduced and when reptiles could have succeeded on drier continents. What is this gulf, and what was a dinosaur? (warning: trick question! Specifically what is the impossible gulf between, for instance, a salmander and a chamelion? } 6) Between reptiles and birds; The ornithischia, with bird-like pelvises appeared before the modern birds, whch began to appear in Cretaceous time. Intermediates are known. } 7) Between reptiles and mammals; The therapsida in permean time, Mammal-like reptiles appear before the first mammals, but intermediate forms are known, and a fairly complete record of the changes in the facial bones between these reptiles and true mammals is known from Permean time. Does anyone know if mammalian dentition is documented into this time. Did the Therapsida have differentialted dentition? } 8) Between mammals and the human body; Man is classified, based on his dentition, with the Primates. All the primates have the same teeth. The fossils that relate to our origins are well understood and dated. The controverseries about the detailed lineages are minor compared with the general phylogeny they document. }12) The failure of some organisms to evolve at all. If it passes the selection filter, no change required. These organisms are excellently adapted to their particular niche in their environment. (like sharks: the "perfect eating machine", right?) Like the brachiopod Lingula, and the cockroach, identifiable through most of the phanerazoic and still with us. If an organism is well adapted to a niche it can readily occupy, then why should it evolve? }- No new phyla, classes, or orders have appeared. Subsequently to what? Trees of descent for organisms are drawn by grouping organisms together based on common features. Twigs which are close together are organisms which differ only in few and minor respects. Main branches, down at the bottom of the tree, are groups of organisms that differ in many and major respects. One of the main premises of evolution is that this tree is (more or less) proportional to time. Asking for a phylum to appear today is asking for a major branch to be up at the tip of the tree--it makes no sense, considering the way such trees are drawn! It is perfectly possible that in several million years there will be recognizable phyla which were just differentiating today, but there is no way to recognize a "new phylum" in the bud. For example, modern plants use two different photosynthesis reactions. It is quite possible that those two groups will eventually be so different that we will call them seperate phyla, because the two reactions probably favor different evolutionary pathways. But how can we know in advance whether or not this will happen? That's what you're asking for when you want to see a new phylum arise today. This is just not true. while most of the phyla present today were present at the beginning of the Cambrian, and their origin is shrouded, there is enough of a fossil record from the so-called eo-cambrain to suggest that some of the animals found in Australia are different phyla that became extinct by the time fossils became abundant. The affinities of several Cambrian groups is by no means clear, and they might be separate phyla, such as the archeocyathids. Our phylum, Vetebrata (Chordata), appears no earlier than Ordovician, and then only the cartilagenous and jawless fish are known. All the other classes appear later than that. Vascular plants, and all more advanced plant phyla appear no earlier than Silurian time. There are now five kingdoms known, based on their biochemistry and there are enough precambrain microfossils to document their appearence. The geochemistry of sediments in Precambrain rocks is understood well enough to establish when the oxygen level of the biosphere was high enough to support modern plants and animals, that comprize two of the five kingdoms. Before this date it can be infered that the Plant and Animal kingdoms did not exist. I am not faliliar with Precambrain events to fix this date, 1.8 billion years B.P. ?, or to document the micro fossils that might bear this out. }- The occurrence of parallel evolution, in which similiar structures evolve } in quite different circumstances. If you start with the same ancestor, they can only vary so much. Also, what he thinks are "different circumstances" are not necessarily so. Physics has an interesting set of constraints... }Many species have remained absolutely fixed throughout geologic time. There are no known examples of organisms that have not evolved over a period of time and this includes cockroaches, lungfish, lampreys, sharks, bacteria, and all other organisms that some people claim are "frozen in time". Some of these species appear to be morphologically similar to ancestors that lived in the past but evolution is much more than external appearance. When the structure of their genes and proteins are examined it becomes obvious that they have evolved at the molecular level. In fact the rate of evolution of these species is similar to that of species whose external appearance has changed more drastically. It is incorrect to claim that some organisms have not evolved simply because their external morphology has not changed. The problem here is that the fossil record only preserves some parts of an organism. The fact that these parts have not changed very much doesn't mean that the species has not evolved. }A great many modern species are very evident degenerate, rather than }higher, forms of those found as fossils. There is no hierarchy to evolution. There is no reason to suppose that modern organisms should be "higher" than extinct ones. Loss of a structure is just as much evolution as gain of one. If Creationists admit that some organisms have become "degenerate" then they are admitting to evolution. }All the great phyla appear quite suddenly in the fossil record. Marvelous. As long as he gets to pick which ones he wants, they do. Collect the data to support you conclusion. Keep throwing out the outliers (97% discarded?) till it fits. }Selection cannot change the frequency of variants Since evolution is, by definition, a change in the frequency of genes in a population, then this statement is equivalent to saying that selection cannot cause evolution. There are many experiments in the literature that directly demonstrate how false and ridiculous this statement really is. Perhaps the easiest examples for the non-biologist are those that involve human selection, as in breeds of dogs or cattle. In those cases selection for distinct characteristics has led to populations with differing frequencies of alleles (variants). Thus selection has been PROVEN capable of changing the frequency of variants or alleles in a population and we have every reason to believe that it did so in the past as well. Directional selection (selection "for" or "against" something) in a static environment will lose variation. To get a more interesting result, you can look at either of two things: 1. Selection which is not directional. Here are some examples: Frequency dependent selection. Forms which are rare are at an advantage. There are several decent real-world examples of this; female fruit flies prefer males who look "different", and animals which have immune system genes different from their neighbors' seem less likely to get diseases from them. Heterozygote advantage. The organism with two different forms of the gene has an advantage over others. The classical example is sickle-cell anemia in humans, where the person with one sickle and one normal allele is protected from malaria. Two kinds of selection pulling in different directions. For example, females may prefer brightly colored males, but so may predators. Some values for the parameters here will give a balance of different forms in the population. 2. Non-static environments. This is much harder to model, but interesting. You can easily get frequency-dependent selection out of an environment with two food sources, both subject to overexploitation. Environments which change over time either randomly or in a cycle can also maintain variability. *** The simplest model I know in which something like speciation can be seen to happen is one that contains two factors: There is a gene with two variants, and the heterozygote is worse than either homozygote. There is the possibility for evolving reproductive isolation based on the first gene. Reproductive isolation could be modeled in several ways. You could explicitly add a gene that controls mate recognition. You could arrange your simulated organisms on a grid and restrict most mating to near neighbors, and see if two populations seperated from an initial mixture. Don't forget that if you use random rather than strictly proportional selection (that is, if you use a random number to see who lives and who dies), population size makes a huge difference. It is almost impossible to maintain high variability in a tiny population, even with strong selection.


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