drosophila kept in dark for 3 generations have eyes  again in 4 generation  disprove which theory?
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Neither, because genetic material is inherited and not lost, probably just lying dormant, waiting to be 'switched on' when the conitions are right. After all, life has to be prepared to wait for environmental changes, or there is no evolution.
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think about the eye.  it's no good if all you have is an eyeball, yet lack an optic nerve to transmit the light as an electric signal, or an occipital cortex to interpret the electric pulses back into a picture.\n\nso how could the eye have evolved?  suppose some primordial worm starts getting two black dots on its head that will eventually turn into eyes.  suppose they eventually turn into eyes.  he still can't see.  this is not a viable mutation as it has no possible survival value or advantage over the other plain ol' worms.  an eye is no good unless every other part of the visual system is already intact.\n\nso a gradual evolving a pair of eyes won't work, since it will hinder the creature's survival before it will actually help it out.  the only way natural selection favours evolutionary andvancements is through ''hopeful monsters.'' a lizard hatching a bird, a worm with no eyes giving rise to one with eyes in a single generation.\n\nand that's another thing.  what if a lizard tried to grow longer and longer scales in hopes that they'd one day become feathers?  well, there comes a point where this lizard has half feather/scales, on some rather cumbersome, yet extremely fragile wing-like ''hands,'' which it can no longer use for running from predators, yet, it still cannot fly.  natural selection would quickly weed out such a transitional creature.\n\nand that's another thing...where are all these transitional fossils that had to be here?  since evolution took place over millions and millions of years, right?  (the earth's age is actually closer to what the bible says, anyway, as the speed of light is slowing down, and used to be much much faster in the past, according to modern quantum physics and other considerations, [see sources] so radioactive decay used to be much faster in the past, making radio-carbon dating yeild ages far too old)....there actually wasn't even enough time for things to evolve.  the only way evolution could've happened was by hopeful monsters...\n\nwhat about the peppered moth, mike?  what about it?  there's a variation in the species.  what about red heads and brunettes? ;-)  okay, what about the tiny 18 inch tall horses in fossil records?  well, modern, wild brown horses can be selectively bred to get tiny little horses like that.  yes, it takes about 80 years, but it can be done.  (evolutionists tend to call this ''micro-evolution'' just to get a foothold ;-)  )  what's more, regular house cats have been successfully bred with lions to produce ''medium sized'' cats.  this only shows that there is a wide variance in the species, but it's still one kind.  evolution states that one species will change so much over a period of time that it cannot breed with other species that have branched off in different directions.
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Yes.  Blind cave fish (info link below) have evolved that way from living in the dark.\nAs far as humans are concerned it would take quite some time for that to happen I would think.\n\nhttp://www.bio.brandeis.edu/~sekuler/senpro/topic_1_stuff/sensory_deprivation.html  is a link to an article about sensory deprivation.
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I think their light-loving behavior has to do with mating. \nYou see, in the dark, it´s very difficult to get together with individuals of the same species, so evolution came up with a great idea: a universal rendez-vous for insects. \nBy moving towards light, the chances of meeting a nice partner climb up. And that is directly related to an enhanced ability to reproduce, the ideal mix of features for any trait to get evolutionarily fixed in a population.
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Since you haven't given the context, you could be right...\n\nY is dominant to y.\nIt may well be that Y (green) is dominant to y (yellow), since often genes are name after what happens when they don't work.  The gene that causes fruitflies to have red eyes is actually called "white".  Stupid, huh?  W (red) is dominant to w (white).  Hope I haven't confused you.
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This is an example of a chimera. We all carry two copies for each gene, one from each parent. Rarely, one copy of one gene can get inactivated in a cell, or in a group of cells.\n\nPeople with two different coloured eyes carry two different eye colour genes, let's say brown and blue. Normally, the dominant gene would be the one you'd see, i.e. brown. If, however, during development the brown gene gets turned off or mutated in a cell that ends up giving rise to the area of the body that makes one eye, then that eye will be blue, and the other brown.\n\nNote that the same thing can happen within one eye - it means that the mutation happened later, so it was in a cell making only part of the iris, rather than the whole iris. There's a summary and theory discussion at the link below.
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COLORBLIND WMEN ARE RARELY FIND. BUT IF SO HAPPEN THEN THE THIRD GENRATION WILL BE AFFECTED N NOT THEIR CHILDRN! AS WMEN HAV XX CHROMOSOMES N MEN HAV XY CHROMOSOME
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it is all genetic orriented , the genes for orange beaks and yellow ones are present but may be reccessive in certain cases. i think it is the yellow gene that is reccessive in the Black birds.
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Two potentially unresolved questions in evolutionary biology are how and why did sex evolve (the big unresolved issue), and why only two as opposed to more sexes is stable. theory allegedly predicts three is more stable and better than two for example.\n\nYour text book anwsers, like recombination to break the linkage between "good" and "bad" genes and to avoid parasites (red queen hypothesis) explain why sex, ONCE it has evolved, is stable and selected for, BUT not how or why it evolved.\n\nPerhaps you should consider work by Lynn Marguilas et al. on the symbiont theory. Although now largely accepted that organelles like the mitochondria and chloroplast are degenearte symbionts, and less accepted that the nucleus is too, extrapolation of this theory would allow (account for) for the evolution of diploidy and reductive meisois (and thus sexual reproduction) by having two organisms (one aerobic the other anerobic) merging and seperating according to the oxygen levels (oxygen was at first a highly toxic compound to life untill aerobic metabolism evolved). \n\nBy the way hemaphrodites are still sexual, even selfing ones.\n\nAnd additionaly please note and remember for future that sexual discrimination, like homosexual discrimination, and so on, is neither a prerequisite nor a product of sexual reproduction.
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Segregate two populations of creatures into separate environments, and see if evolutionary differences between the two populations occur over many generations. That's the sort of experiment the bible thumpers would have to twist logic into a pretzel in order to refute.
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To understand this phenomenon, you need to know about phototaxis. Phototaxis is an organism's automatic movement toward or away from light. Cockroaches are an example of a negatively phototactic organism. You've probably noticed how they scurry back into dark corners and crevices when you illuminate their late-night snacking party in your kitchen. Moths are positively phototactic. They seem charmed by your porch light, your headlights or your campfire (even if it leads to their untimely demise). While there is no definitive explanation for this phenomenon, there are some interesting theories.\n\nSome types of moths are known to migrate, and it's possible that the night sky gives them navigational clues. A moth's up-down orientation might depend in part on the brightness of the sky relative to the ground. Some lepidopterists (moth and butterfly scientists) suggest that moths use the moon as a primary reference point and have the ability to calibrate their flight paths as the Earth's rotation causes the moon to move across the sky. (There is even evidence to support the theory that migrating moths have an internal geomagnetic compass system to guide them in the right direction.) So a moth's attraction to an artificial light or to a fire could be related to orientation, and lead to disorientation -- the moth wasn't "expecting" to actually get to "the moon" (the light source) or to be able to fly above it, so confusion results.\n\nIt's also possible that moths have an escape-route mechanism related to light. Imagine disturbing a bush-full of moths at night -- they all fly up and out of the bush, toward the sky. To a moth in danger, flying toward the light (which is usually in the sky, or at least upward) tends to be a more advantageous response than flying toward darkness (which is usually downward).\n\nMoths are more sensitive to some wavelengths of light -- ultraviolet, for example -- than they are to others. A white light will attract more moths than a yellow light. Yellow is a wavelength moths don't respond to.\n\nAnother interesting question is: Why do moths stay at lights? A moth's eyes, like a human's eyes, contain light sensors and adjust according to the amount of light the sensors detect. In high illumination, light from each of the moth's thousands of fixed-focus lens facets is channeled to its own sensor (ommatidium). In low illumination, light from multiple lenses is channeled to the same ommatidium to increase light sensitivity. You probably experience a few moments of blindness when you turn on a bright light after your eyes have adjusted to darkness, or when you are suddenly in darkness after being in bright light. A moth's dark-adapting mechanism responds much more slowly than its light-adapting mechanism. Once the moth comes close to a bright light, it might have a hard time leaving the light since going back into the dark renders it blind for so long. In the case that the moth escapes, it won't remember the problem with flying too near the light and will probably find itself in the same predicament all over again.\n\nAnother possible explanation for why moths stay at lights is that they are mostly night-flying creatures and eventually respond to the light as they would to the sun -- by settling in for their daytime "sleep."
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http://en.wikipedia.org/wiki/Drosophila_melanogaster
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Really rare, since there are SEVERAL genes that control eye color, and then you have to worry about the issue of genetic complementation. If you know the allele frequency of each genes that control eye color, it is a very small number, but it is still possible.
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Scientists said Thursday that they had discovered a tiny genetic mutation that largely explains the first appearance of white skin in humans tens of thousands of years ago, a finding that helps solve one of biology’s most enduring mysteries and illuminates one of humanity’s greatest sources of strife. \n\nThe work suggests that the skin-whitening mutation occurred by chance in a single individual after the first human exodus from Africa, when all people were brown-skinned. \n\nThat person’s offspring apparently thrived as humans moved northward into what is now Europe, helping to give rise to the lightest of the world’s races. … \n\nThe newly found mutation involves a change of just one letter of DNA code out of the 3.1 billion letters in the human genome—the complete instructions for making a human being. \n\n“It’s a major finding in a very sensitive area,” said Stephen Oppenheimer, an expert in anthropological genetics at Oxford University who was not involved in the work. “Almost all the differences used to differentiate populations from around the world really are skin-deep.” … \n\nThe discovery, described in today’s issue of the journal Science, was an unexpected outgrowth of studies that study leader Keith Cheng and his colleagues were conducting on inch-long zebrafish, which are popular research tools for geneticists and developmental biologists. \n\nHaving identified a gene that, when mutated, interferes with its ability to make its characteristic black stripes, the team scanned human DNA databases to see if a similar gene resides in people. \n\nTo their surprise, they found virtually identical pigment-building genes in humans, chickens, dogs, cows and many other species, an indication of its biological value. \n\nThey got a bigger surprise when they looked in a new database comparing the genomes of four of the world’s major racial groups. That showed that whites with Northern and Western European ancestry have a mutated version of the gene.\n\nSo, what does this mean?  It strikes a blow into everyone, from the racist white right to the black nationalist left, who seeks to elevate one race over another.  In short, we are all niggers now. \n\nBut here’s a thought.  If white people came from black people, and black people were the first people on Earth, and God made man in His image, then God is black.  Chew on that one for a while.
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The Genetics of Human Eye Color\nCan a baby's eye color be predicted using the eye color of the parents, grandparents and siblings?\nEye color is a physical trait that is genetically determined. A favorite pastime for many expectant parents is documenting the eye color of grandparents and extended family members to attempt to predict the eye color of their baby. Any discussion of the inheritance of eye color, requires a review of genetics. In basic terms, eye color is determined by the amount of a pigment called melanin that is in the iris of the eye. Brown eyes have lots of pigment, blue eyes very little. The amount of pigment is determined by a number of genes controlling pigment production. Generally speaking, brown is dominant, meaning that if one parent has brown eyes and the other has blue eyes, the baby will most likely have brown eyes. But the situation is really much more complicated than that. For a more complete description, read on. \n\n\nWhat is a gene and what does it have to do with eye color?\nHumans have a diploid number of 46 chromosomes (23 pair) located in the cell nucleus. In the process called meiosis, sperm and egg cells are produced that have the haploid number (23) of chromosomes. During fertilization of the egg by the sperm the diploid number of 46 is restored. During the course of pregnancy, the fertilized egg (zygote) undergoes a complex series of changes including multiple cell divisions and differentiation of cells into the different organ systems. The result is a baby whose cells each have 46 chromosomes. One chromosome of each pair is inherited from the baby's father and the other from the mother. A gene is a length of DNA on a chromosome that does something particular for an organism. It is the basic unit of heredity, determining the observable characteristics, or phenotype, of an individual. The actual genetic makeup of an individual is referred to as its genotype. Genes are arranged in a linear fashion on the chromosome, much like beads on a string. The arrangement of genes along a chromosome is the same for both members of a chromosome pair. Therefore genes also occur in pairs. \n\n\nIf genes occur in pairs are both genes alike?\nGenes may occur in different forms called alleles so the appearance of any characteristic is dependent on the types of alleles present. A person who carries two of the same alleles is called homozygous for that gene. If two different alleles are present the person is heterozygous for that gene. In a heterozygous gene pair, one allele may be expressed over the other. The allele that is expressed is called the dominant allele. The allele that is not expressed is called the recessive allele. Dominance and recessiveness refer to which allele is expressed when the two occur together. There is nothing abnormal or defective implied in the terms. Examples of dominant/recessive inheritance are many of the famous genetic experiments conducted by Gregor Mendel. Mendel bred pea plants and found that crosses between homozygous purple flower plants and homozygous white flower plants always produced plants with purple flowers. In the process of incomplete dominance, a heterozygous gene pair produces a characteristic that is intermediate between the characteristic produced by the homozygous condition of each allele. An example of this occurs when a red snapdragon is crossed with a white one resulting in a plant with pink flowers. In a third process called codominance, the affect of each allele is expressed simultaneously. An example of codominance is the human AB blood group system in which a person with an A allele and a B allele will have type AB blood. \n\n\nI have heard that a single pair of genes determines what color my eyes are. Is this true?\nAt one time scientists thought that a single gene pair, in a dominant/recessive inheritance pattern, controlled human eye color. The allele for brown eyes was considered dominant over the allele for blue eyes. The genetic basis
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Phenotype frequency:\nDo you know what a phenotype is?  It's the result of the genotype and environmental influence.  In other words, it's the organism's physical characteristics (and some other things).  A phenotype could be green eyes, red hair, pale skin, and freckles, or simply green eyes.  The phenotype frequency is just how often that phenotype occurs in the population.  So if green eyes occur in 5% of the population (note I'm just making up the number), the frequency of the phenotype green eyes is 5% or 0.05.\n\nSympatric speciation:\nSympatric speciation refers to speciation that occurs within a population in a single location (as opposed to speciation that occurs as the result of geographical isolation).  The most frequently observed example of sympatric speciation is polyploidy in plants.  In most animals, a complete extra set of chromosomes is generally really bad, but for plants it can be just fine, or even a good thing.  When, through random chance, a plant receives a complete extra set of chromosomes (so it now alternates between tetraploid and diploid rather than dipliod and haploid), it can no longer produce fertile offspring with the members of the parent species (the offspring would be triploid, which makes meitosis impossible - if you'd like me to explain this in more detail, just ask).  Thus the new tetraploid (4n) plants are a separate species from the original diploid (2n) plants.  Becaues the new species arose without a geographical barrier (a mountain range, river, etc. separating the two populations), this is an example of sympatric speciation.\n\nPostzygotic isolation:\nFor starters, do you know what a zygote is?  It's the result of fertilizaition.  Post- means after, so postzygotic means after fertilization.  I assume you know what isolation means :), so postzygotic isolation is reproductive isolation that occurs after fertlization.  Basically, the sperm of one species can successfully combine with the egg of another species, but the resulting zygote will either be inviable (i.e. it will die in the early stages of embryonic development) or grow into an infertile organism.
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Mendel's law of dominance\nIn a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. Offspring that are hybrid for a trait will have only the dominant trait in the phenotype. \n[edit]\nMendel's law of segregation\n \nFigure 3 : The color alleles of Mirabilis jalapa are not dominant or recessive.\n(1) Parental generation. (2) F1 generation. (3) F2 generation. The "red" and "white" allele together make a "pink" phenotype, resulting in a 1:2:1 ratio of red:pink:white in the F2 generation. \nFigure 1 : Dominant and recessive phenotypes.\n(1) Parental generation. (2) F1 generation. (3) F2 generation. Dominant (red) and recessive (white) phenotype look alike in the F1 (first) generation and show a 3:1 ratio in the F2 (second) generationMendel's law of segregation, also known as Mendel's first law, essentially has four parts.\n\nAlternative versions of genes account for variations in inherited characters. This is the concept of alleles. Alleles are different versions of genes that impart the same characteristic. Each human has a gene that controls eye color, but there are variations among these genes in accordance with the specific color the gene "codes" for. \nFor each characteristic, an organism inherits two genes, one from each parent. This means that when somatic cells are produced from two gametes, one allele comes from the mother, one from the father. These alleles may be the same (true-breeding organisms, e.g. ww and rr in Fig. 3), or different (hybrids, e.g. wr in Fig. 3). \nIf the two alleles differ, then one, the dominant allele, is fully expressed in the organism's appearance; the other, the recessive allele, has no noticeable effect on the organism's appearance. In other words, the dominant allele is expressed in the phenotype of the organism. However this does not always hold true: Today, we know several examples that disprove this "law", e.g. Mirabilis jalapa, the "Japanese wonder flower" (Fig. 3). This is called incomplete dominance. There is also codominance on a molecular level, e.g. people with sickle cell anemia, when normal and sickle-shaped red blood cells mix and prevent malaria. \nThe two genes for each character segregate during gamete production. This is the last part of Mendel's generalization. The two alleles of the organism are separated into different gametes, ensuring variation. \nDuring his experiments, Mendel encountered some traits that did not follow the laws he had encountered. These traits did not appear independently, but always together with at least one other trait. Mendel could not explain what happened and chose not to mention it in his work. Today, we know that these traits are linked on the same chromosome.\n\n[edit]\nMendel's law of independent assortment\nAlso known as Mendel's Second Law \nThe most important principle of Mendel's law of independent assortment is that the emergence of one trait will not affect the emergence of another. While his experiments with mixing one trait always resulted in a 3:1 ratio (Fig. 1) between dominant and recessive phenotypes, his experiments with mixing two traits showed 9:3:3:1 ratios (Fig. 2). Mendel concluded that each organism carries two sets of information about its phenotype. If the two sets differ on the same phenotype, one of them dominates the other. That way, information can be passed on through the generations, even if the phenotype is not expressed (F1 generations, figures 1 and 2).\n\nMendel's findings allowed other scientists to simplify the emergence of traits to mathematical probability. A large portion of Mendel's findings can be traced to his choice to start his experiments only with true breeding plants. He also only measured absolute characteristics such as color, shape, and position of the offspring. His data was expressed numerically and subjected to statistical