FreeThinker

Amazing.

I have no doubt that introduced animals can adapt to their new environments. However, how do local species adapt to the introduced animals. For example, the coyote in your example might be adapting well but how are other predators in that area adapting to the coyote? Even if the other predators did adapt to the coyote, surely it’s a rare case. Introduced species often cause irreversible damage. Foxes, rabbits, feral pigs cause havoc in just about every place where they are introduced. At the very least it leads to the extinction of local species. I guess the real question is how much long term damage does it cause to the ecosystem? You could argue that the environment will change by simply adapting to the introduced species. But in that case we shouldn’t worry about any animals going extinct because the environment can adapt and possibly provide a path for new species to evolve.

A good teacher shows passion and enthusiasm for the subject that they are teaching. There is nothing worse than monotone teachers reading of the lecture notes. When a teacher starts lecturing you can tell weather they truly enjoy what they are teaching. This greatly affects the students, or at least myself. I remember when I had a lecture on Evolution in Biology and the teacher spoke with so much passion and knowledge that I did not want to leave ( and I actually listened to the audio of that lecture a couple of times). On the other hand, when I was doing genetics, and equally fascinating subject, I was asleep half way through, the teacher showed no passion or interest in the subject. He didn’t walk around and demonstrate, with hand actions, the subject matter. He just read the lecture notes on his laptop. I also like a teacher who gets the students involved by asking questions. It keeps me alert during the lecture and it really helps me remember. Good interaction is definitely important. But most of all a good teacher should give the students the time of the day. I always like to approach my professors about a recent book iv read, or something that on my mind. The difference between a teacher who cares and one who doesn’t is self evident in the look they give you.

Since the emergence of our ability to understand and manipulate the world, humans have been changing the face of the planet. It is not just ourselves that we are affecting. In the same way that natural selection has been applying pressure on life for millions of years, humans have been doing so more recently. An important difference between natural and Homo sapien selection (H.S.S) is that the later is happening at a much faster rate. Our ability to travel around the globe in short period of time has altered many ecosystems around the world. Rats, cats, dogs, foxes etc are all common companions to traveling humans. Once transferred to a foreign location, local animals have to adapt to the intruders. They have to adapt to the Homo sapien way. In Australia, the domestic animals are being driven to extinction by the feral cats and rabbits. Undoubted, natural selection has a role to play in this. But does natural selection have enough time to act? How might animals, if at all, adapt to this HSS selection pressure? Can natural selection compete with HSS selection? Only victory I see for natural selection is the parasites that infect humans. This is perhaps the best example of the arm race between HSS and natural selection. The HIV virus is an example of nature being able to act at extremely fast speed. But is such fast selection always doomed for the simplest of forms of life? I am assuming here that viruses are a form of life, which would be inaccurate according to many definitions. If you don’t consider viruses a form of life, can nature keep up at all? Are any animals that are affected by H.S.S, capable of adapting?

As usual I found myself wondering around the science section of a local bookstore. I tried to convince myself that I should finish reading one of the seven books by my bed before spending anymore of my, rent, money. After browsing the covers of numerous books, I was just ‘looking’, one caught my eye. A very visible font read: “Richard Dawkins”. I picked it up assuming, wrongly so, that this was Dawkins biography. I usually have a habit of reading the preface of the book I have my eye on, this time I went straight to the register. I started reading the book in the car when I walked out of the bookstore. Two days after, of non-stop reading, I have just put it down. The book is a collection of essays from a wide range of fields including biologists, writers and philosophers. They all describe the ways in which Dawkins has affected their academic life, field of study or the effects of his books, mostly the selfish gene, on the way we think of evolution. The first section, titled ‘Biology’, is a collection of essays describing how the genes eye view of evolution is sculpturing their research and how Dawkins’s explanation had shed a new light on evolution that continues to this day. The sections titled ‘The Selfish Gene” addresses this now infamous book and its impact on humanity, the view of culture (through Memes) and arguments for a reductionism approach when dealing with human behavior. The next three sections (Logic, Antiphonal Voices and Humans) contain essays that continue the Selfish gene theme and address the impact of Dawkins writing on some fundamental human questions. The sections titled ‘Controversy’ reviews the most controversial side of Dawkins, the Dawkins that is never afraid to be straight forward when attacking religious dogma and promoting atheism. Finally the section on ‘Writing’ sums up this book perfectly. In the midst of all the controversy and scientific arguments it is not difficult to forget that Dawkins is truly mesmerizing with words. The two essays in this section sum up his writing technique and perhaps clarify why even those who don’t agree with his views are so captivated by his books. If you are a fan of Dawkins, or even if you are not, this is a must have.

I think the problem is that Dawkin's statements are often over analysed. Mutations are random events. Natural selection is very much NON random. However, death can strike the most adapted organism. Saverian attempted to take the meaning of "non randomness" out of context. Sure, a well adapted organism could be killed by lightning , or eaten by a 'lucky' predator. But a organism which is less adapt will have a bigger chance of being eaten. For natural selection to be truly random both , the well adapt and the less adapt, would have to have the same chance of being picked to be eaten. This not the case. The organism with the evolutionary advantage will be in the minority and therefore even chance will be on its side. As it spreads its genes, the populations will slowly start being better equipped at surviving in the particular environment. Eventually a significant portion of the population will be better equipped to survive that the rest. This is where the odd death of the better equipped organisms is even less significant ( as its genes would already be spread through out the population). Natural selection is the random in the same sence as a person choosing a mate. Anyone has a chance of being chosen by a particular member of the opposite sex. However, some individuals have an advantage over others( according to the taste of the selector). Once in a while someone might be tricked into marring someone but usually choosing of a partner is based on preferences and compatibility, not random chance.

Maybe they would be better off under Saddam. Maybe they wouldn't. It is not American right to make those decisions. Maybe the terrorists think American people would be better under a different government, so they tried to blow up the Pentagon? My point is that America went into Iraq based on a belief that Iraq possessed weapons of mass distruction. They did not. However, America has stayed in Iraq and this has caused a lot of innocent deaths. You think its for the good of the Iraqi people? Tell that to the mothers who lost children as a result of the American invasion. Tell that to the mothers of dead American soldiers. The war is unjustified. The terrorists in Iraq are a tiny minority. It is not logical to bomb an entire nation to get to a few bad guys. Depends how many innocent people will be sacrificed in hunt for Osama. As a fundamentalist leader, he can be replaced. Lives lost can not. Do you know what makes fundamentalists? Its not one guy brainwashing people. Its when a child loses his/hers parent as a result of American bombing and they have nothing to live for but revenge. When a father loses an only daughter. When someones house is destroyed and they have to watch their children starve to death. That's what causes fundamentalists. When you have lost everything, you are an easy person to persuade to become a suicide bomber. No matter how many 'leaders' America kills, the seed of hate has already been planted in Iraq.

I am supporting Australia. But it is hard look beyond Brasil when predicting the winner. They really have an outstanding team.

I am sure the Americans children who die as the result of the fueled hatred will need a pillow on their coffins.

Can anyone spare a though for the dead woman and children that died during this USA air strike? Only a naive person could think that the death of Zarqawi will make the situation any better in Iraq. If anything, it will get worst. The death of a leader will only encourage more fundamentalists to retaliate and seek revenge. The whole war is largely unjustified and too many innocent people have died on both sides.

To kill off any harmful pests that could destroy the food during storage. In third world countries the stock saved by food irradiation saves thousands of lives each year.

Very true. It is a shame that the potential of nuclear energy for good use (food irradiation , material testing, medical purposes etc.) is not publicised by the media. However, they are quick to mention nuclear weapons, nuclear accidents and anything else giving nuclear use a "bad name". I do not wish to be misunderstood. I do see the potential in nuclear energy to be a valuable, and an efficient , way of providing power. I am just questioning the timing of the idea. I will admit that my knowledge of the disposal techniques for nuclear waste is weak at best. I will read through the Canadian websites posted in a previous post.

They could be misinformed, not interested and possibly ignorant. To call them dumb is, well , dumb...

You can not be serious! What about all the woman and children that would day in the process? I hope you were joking...

Recent debate in Australia is weather the country should go nuclear ( power plants). Nothing is certain, but the cards are on the table. John Howard appears to be in favour of the idea. I am not so sure. Firstly, we have natural gas resources and by the time they are depleted some new technology could emerge. If not, we can always go back to nuclear power. And what to do with all the waste? We can bury it in sand but even then background radiation could cause problems. A much better alternative, in my opinion, is investing in hydro or solar power on mass scale. We have a enormous amount of space for either of these two options. Another problem with nuclear power is the time the idea is suggested. There is a possibility Iran will be invaded because of their plans to develop nuclear power plants, at least thats what they say. I am sure many people will be asking, why the double standard ?

Hello all, I recently wrote an essay on endosymbiosis. I have received feedback from the teachers, but it wasn’t very satisfactory in my opinion. So I figured that if any of you guys could give me some constructive feedback it would only help me improve .Any feedback will be greatly appreciated! -------------------------------------------------------------- Endosymbiosis provides an explanation for the origins of DNA-containing organelles. Critically evaluate the evidence for and against this theory. Introduction It is rather ironic that Darwin’s now famous book “On the Origins of Species” never dealt with how species originate. To explain natural phenomena such as the origins of Eukaryotic cells, Darwin’s explanation of a gradual accumulation of beneficial mutations might not be the whole story; endosymbiosis is the theory that attempts to fill the gap. Symbiosis is used to refer to the relationship between a host (animal or plant) and the smaller organisms (the symbiont). The term “endosymbiosis“ refers to the relationship where a symbiont lives within the host. Endosymbiosis provides an explanation for the origins of plastids and mitochondria, proposing that they were once free living bacteria that merged with a host organism to form Eukaryotic cell (C. Mereschkowsky, 1905), (Margulis 1970). This essay will critically evaluate the evidence in support of the theory through; the observation of endosymbiosis in nature, organelle function, modern advancements in genomics, DNA sequencing and the fossil record. The evidence against the theory will also be assessed. Both sides of the argument will be considered in establishing how well the evidence supports or refutes the theory that endosymbiosis is responsible for the origins of organelles in Eukaryotic cells. Symbiosis and endosymbiosis in nature Numerous life forms on this planet are committed to a cooperative relationship; from the bacteria in the dog’s stomach to Ophrydium, a ciliate that accommodates a colony of symbiotic bacteria who function as a single individual, (Margulis, 1998a). Termites depend on the micro-organisms that live in their guts to digest wood and in return the micro-organisms depend on the termites to find wood, (Dawkins, 1999). Recently two scientists, (Okamoto – Inouye, 2005) have observed the early stages of endosymbiosis in Hatena, a flagella found in Japan that has acquired a green “placid” and both, the host and the symbiont, have undergone changes to suit one another. Most importantly the placid is only inherited by one daughter cell, confirming that it is a symbiont, (Okamoto – Inouye, 2005). The fact that organism migrate into cooperation with other organisms is an observed phenomenon in nature; the question is whether the organelles of Eukaryotic cells had a symbiotic origin. Early observations In his book Lectures on the Physiology of Plants, Sachs (1882, cited by U. Kutschera) proposed that chloroplasts are independent organisms capable of reproducing independently of the cells nucleus. Almost a decade later, Altman (1890, cited by U. Kutschera et al) observed similarities between mitochondria and free living bacteria. Endosymbiosis , as an explanation for the origins of organelles in Eukaryotic cells, remained highly speculative in the scientific community until the Russian botanists, (C. Mereschkowsky, 1905a) published a landmark paper presenting three lines of evidence in favor of endosymbiosis: (1) chloroplast are transmitted from generation to generation and are never made new from the nucleus of the cell, (2) the close resemblance between plastids and free living cyanobacteria and (3) the resemblance of chloroplast and zoochlorellae (bacteria that live in other organisms). The advancement in genetics has further increased the evidence for the bacterial origins of chloroplast and mitochondria. Bacterial ancestry and genetic evidence Despite the hundreds of millions of years spent in the host cell, the chloroplast endosymbiot retains the characteristics of its bacterial ancestry, (McFadden, 1999). Mitochondria and chloroplast retain “genes, metabolic activities, genetic mechanisms and protein import complexes” that clearly establishes their prokaryotic origins, (Osteryoung and Nunnari, 2003). The DNA of the organelles indicates that they are more closely related to prokaryotic cells than their Eukaryotic hosts, (Archibald, 2005). Further analysis of DNA data has identified two groups of bacteria, α-Proteobacteria and Cyanobacteria as the closest relatives of mitochondria and chloroplast, respectively, (Gray-Spencer, 1996). This evidence has further strengthened the case for a bacterial ancestry of the organelles (Douglas and Raven, 2003). Plastids and mitochondria do not just resemble bacteria; they behave like bacteria as well. (Mereschkowsky, 1905) They grow, divide and produce substances synthetically without dependents on the nucleus of the cell, (Mereschkowsky, 1905b). However, the organelles are not completely independent of the nucleus. They have surrendered their metabolic functions to the host cell, (Margulis, 1970). Cooperation with the host DNA transfer from the nucleus to organelle is a, frequent, ongoing process which has been observed in laboratory experiments, (Huang, 2003). Genetic analysis has established that the eukaryotic cell nucleus contains ancient bacterial genes that have been transferred from the plastid organelles, (Archibald, 2005). How this protein chain evolved is one of the biggest mysteries of endosymbiosis. Margulis (1970) suggests that the same natural selection pressure that drives cave animals to lose their eyes would drive the endosymbiot to develop cooperation with the host nucleus, and vice-versa. Fossils record Another piece of evidence in favor of endosymbiosis is the fossil record. No fossil evidence has been found of intermediates between placid-lacking organisms and plastid containing organisms, as would be expected if the organelle evolved by slow accumulation of random mutation. However if the plastid merged with the host via endosymbiosis no such intermediated would exist (Margulis, 1970). This observation agrees with the theory of “Punctuated Equilibrium” which claims that evolution is not a gradual process but a process of stops and spurs, and that species can appear suddenly ( in evolutionary time) (Gould, 1980). Critiques of the theory The opposite view of endosymbiosis is the autogenous hypothesis, which claims that the organelles evolved inside the cell and were never free organisms (Cavalier-Smith. 1975, cited by U. Kutschera et al). It is also argued that not enough is known about the DNA makeup of mitochondria and plastids, and until further research is done the origins of the organelles in eukaryotic cells will remain a mystery. (Lang et al, 1999). Even though the fossil record seems to support the theory of endosymbiosis, the gradualist view points out how unlikely it is for organisms (especially bacteria) to fossilise and that the ‘gaps’ in the fossil record exist because animals failed to fossilise, not because it reflects what really happened in evolutionary history (Dawkins, 1996). Conclusion Through the observation of endosymbiosis in nature, DNA sequencing of the organelles which indicates a bacterial origins and the fossil record evidence in support of endosymbiosis, the puzzle of how mitochondria and chloroplast originated in Eukaryotic cells is starting to come together. Even though many aspects of the theory remain unknown, no alternative hypothesis can fit the evidence as well as endosymbiosis, (Martin-Kowallik, 1999). Darwin proposed that complexity is the result of billions of years of evolution. It was Darwin’s ‘bulldog’ Huxley who was skeptical of this view. Huxley believed evolution could progress so rapidly that the slow process of rock sedimentation would never catch the act. If endosymbiosis did occur in eukaryotic cells, it would have been an instant event and a truly giant leap in evolution of life on earth. The British geologist, Derek. V. Agar wrote: “The history of any one part of the earth, like life of a soldier, consists of long period of boredom and short periods of terror.” With the current evidence supporting endosymbiosis, he was probably right. References Altmann, 1890 R. Altmann, Die Elementarorganismen und ihre Beziehungen zu den Zellen, Verlag von Veit & Comp., Leipzig (1890). cited by U. Kutschera and K.J. Niklas , 2005 Endosymbiosis, cell evolution, and speciation vol. 124 pp. 1-24 Archibald, M.J, 2005, ‘Jumping Genes and shrinking Genomes – Probing the Evolution of Eukaryotic Photosynthesis with Genomics ‘, Life vol. 57, pp. 539-547 Dawkins R, 1999 ‘Unweaving the rainbow’ Penguin Books pp. 229-230 Dawkins R, 1996 ‘The Blind Watchmaker’ W.W Norton pp.223-225 Douglas A E., Raven J.A., 2003 ‘Genomes at the interface between bacteria and organelles’ Phil. Trans. R. Soc. Lond. B 358 (2003), pp. 5–18 Cavalier-Smith, 1975 T. Cavalier-Smith, The origin of nuclei and of eukaryotic cells, Nature 256 (1975), pp. 463–468. ) cited by U. Kutschera and K.J. Niklas , 2005 Endosymbiosis, cell evolution, and speciation vol. 124 pp. 1-24 Gray MW, Spencer DF. 1996. Organellar evolution. In Evolution of Microbial Life,ed. DM Roberts, P Sharp, G Alderson, MCollins, pp. 109–126. Cambridge: CambridgeUniv. Press Gould S. J, 1980 ‘ The Episodic Nature of Evolutionary Change’ The Panda’s Thumb W.W Norton , pp. 179.186 Huang, C. Y., Ayliffe, M. A., and Timmis, (2003) ‘Direct measurement of the transfer rate of chloroplast DNA into the nucleus.’ Nature vol. 422 72-76. Lang et al., 1999 B.F. Lang, M.W. Gray and G. Burger, Mitochondrial genome evolution and the origin of eukaryotes, Annu. Rev. Genet. 33, pp. 351–397. Lynn Margulis (1998), The Symbiotic Planet: a new look at evolution, First edition, Published by Weidenfeld & Nicholson, London Lynn Margulis (1970) ‘Origin of Eukaryotic Cells’ Yale University Press Mereschkowsky, C. (1905). U $ ber Natur und Ursprung der Chromatophoren im P¯anzenreiche. Biol. Centralbl., 25: 593±604. English translation in Martin, W., Kowallik, K. V. (1999). Annotated English translation of Mereschkowsky's 1905 paper `U $ ber Natur und Ursprung der Chromatophoren im P¯anzenreiche '. Eur. J. Phycol., 34: 287±295. Martin W, Kowallik K , (1999) ‘). Annotated English translation of Mereschkowsky's 1905 paper `U $ ber Natur und Ursprung der Chromatophoren im P¯anzenreiche '. Eur. J. Phycol., 34: 287±295. Osteryoung and J. Nunnari 2003 K.W., The division of endosymbiotic organelles, Science 302, pp. 1698–1704. Sachs, 1882 J. Sachs, Vorlesungen über Pflanzen-Physiologie, Verlag W. Engelmann, Leipzig (1882) cited by U. Kutschera and K.J. Niklas , 2005 Endosymbiosis, cell evolution, and speciation vol. 124 pp. 1-24

Agnostic, Imagine two rabbits of opposite sex. If we allowed these two rabbits to mate, and all their offspring survived, and all their offspring survived, and all their offspring survived… the world would be over run by rabbits in a very short time. However, this does not happen. Here is why: 1) Predators will eat a number of individuals 2) There is a limited amount of food supply , and each individual will compete with other individuals for food 3) Potential mates are limited, and each individual will compete with other individuals for mates 4) Each individual rabbit is different and hence each will have a different chance of escaping predators, surviving or finding food. The rabbits that have a disadvantage (slower running speed, more distinct colours attacking predators) will, on average, tend to get eaten, die or fail to reproduce. Ultimately, in evolutionary perspective, this will mean the rabbit will not pass its genes on to the next generation. The better equipped rabbit will pass on its genes. Now imagine a species of rabbits that get separated by a newly formed river. Different traits might be favored in the two different groups. One side might have an abundance of a certain type of food which can only be eaten by long teeth (individuals with short teeth are unable to eat the food, for whatever reason). Individuals with shorter teeth will not be able to feed and eventually the population will be dominated by rabbits with longer teeth (because the longer teeth rabbits eat more food, hence don’t die and live long enough to pass on their genes on to the next generation”). On the other side of the river the rabbits might be favored for shorter teeth because of the food present. For the same reason as the original side, the population will become dominated by individuals with shorter teeth. Imagine this sort of selection happening on the ears, body shape, eyes and molecular structures. Eventually, give it a few million years; the genomes of the two species will be so different that they will not be able to reproduce with each other. It is all logic, logic supported by a mountain of evidence. Humans have successfully made hundreds of species of dogs by choosing individuals for their desirable characteristics. This has been done in only a few thousand years, imagine what nature can do in 3 billion!

Science is the only tool we have for answering our questions. Will it answer all the questions? I dont know, but it has answered a lot of questions thus far ( including the way life devlopes on earth).

I have : Chemistry Biology Statistics How do you people deal with the pre exam jitters?

We already know that the membrane molecules (lipids with hydrocarbon tales and a phosphate group) arrange themselves in such a way that: The hydrophilic end (Phosphate group) faces towards water and encloses the hydrophobic end (the hydrocarbon tales). So a membrane can form, and does in the lab, according to the laws of physics. Now imagine how this would have created a different environment from the one on the outside of the membrane. Different chemicals would have either made this membrane a) more stable or b) cause it to collapse. So even at this level, which can be explained by the laws of physics, some form of selection took place.

“Of course we must be open-minded, but not so open-minded that our brains drop out.” Richard Dawkins

Fair enough. Good idea

Excuse my interruption but what is this letter going to achieve? Do you think the people who made this video will really pay attention to it? Do you all think scientific truth is what they really want?

Are you also open minded to the fact that computers might be operated by little green men?

Weather science will have the answers to all our questions is unknown. I personally believe that it will take us a very long way. The point is, and I will use your metaphor, that the road thus far has been fairly straight. I am not implying that no mistakes have been made; in fact science couldn’t progress without the mistakes. If you are willing to accept scientific discoveries behind practical technology as "fact" than you should, by logic, accept the theory of evolution. You can’t have your cake and eat it too.