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Evolution
The scientific theory according to which populations change gradually through a process of natural selection.
5,264 Questions
Do variations in populations lead to new species?
Variations in offspring are acted upon by natural selection: some offspring will be slightly more proficient at producing new offspring than others. This means that some alleles will promulgate throughout the population gene pool at a faster rate than others, resulting in a shifting frequency of incidence in the population gene pool. This is what evolution is: shifting allele frequencies in the population gene pool.
DNA or deoxyribonucleic acid is an important component in all organisms. Three of its functions are: to carry the genetic and hereditary material, to replicate itself to produce new cells, and for protein synthesis.
What is the concept of survival of the fittest?
Charles Darwin defined natural selection as relating to the members of the species who were the most successful in survival skills (ie finding food, avoiding enemies, living to adulthood were the ones who had children and so propagated the species with their genes).
It should be noted that the Charles Darwin didn't use the term 'survival of the fittest', it was coined by biologist, sociologist, and author Herbert Spenser in his Principles of Biology published in 1864, five years after Darwin's On The Origin of Species. He used the term in his discussion of Darwin's book.
In the context of 'survival of the fittest', the word 'fittest' means best suited to its environment.
What is a drawback of inbreeding?
Inbreeding (and sometime back breeding) is used to reinforce or strengthen certain genetic traits - making them dominant.
For example this process is used extensively in agricultural seed development, where you want to breed seed-lines that are identical when grown by farmers.
What is evolution and who is associated with it?
Evolution is the development of new characteristics and species over many generations which arises from changes in the environment. The idea (which has been called the single best idea ever had by a person) was that of Charles Darwin, an English naturalist and geologist.
The theory of natural selection comes along too. That is a random decision in which a species either thrives or becomes extinct. But sometimes extinction is caused by human interactions and environmental issues; not just by natural selection.
What is the primary mechanism that is responsible for evolutionary change?
Evolutionary change is generally a result of subtle morphological changes of an organism. These changes begin with genotypic mutations, often involving module duplication or deletion (a module being a unit on an organism that is easily adapted, such as segments, legs, or wings). If this change is adaptive (that is, it helps the organism survive), the gene will be passed on to the offspring (natural selection). Genetic mutations also help alter fully functioning features of organisms. For example, the ancient protein globulin originally existed in bacteria as a way to bind and carry oxygen. Over the centuries, mutations to the structure of globulin has expanded its role in organisms so that it functions differently in different tissue (e.g. muscle tissue versus fetal tissue)
Essentially, evolutionary change can affect a protein's diversity in function, its frequency of expression, heterochromy (i.e. change in timing of developmental events, or the change in time of expression of a protein), allometric growth (i.e. change in rate or dimension of growth, such as wings versus limbs), and many other forms of adaptation. However, it is important to note that everything is determined by a combination of nature and nurture. By nature, I mean genetics, and the pathway of gene to RNA to protein. Genes are the blueprints for proteins, which are ultimately the building blocks for organisms. However, the environment (nurture) interacts with the ability for genes to produce these proteins through processes such as methylation (which essentially determines how accessible a gene is). Mutations can also cause genetic deletions, translocations, inversions, duplications (etcetera) which affect protein expression. These types of mutations are often seen in diseases like sickle cell anemia. A genetic mutation inhibits the ability of hemoglobin to form the appropriate protein structure for red blood cells. These types of mutations often involve a loss of function, although they may still be categorized as evolutionary change.
In the end, evolutionary change is a constant, continuous process. To be cheesy: it's happening right now! :-)
http://evolution.berkeley.edu/evolibrary/article/0_0_0/evodevo_05
What is the mechanism that allows organisms to evolve?
1) Natural Selection
2) Climate changes
3) Geographical events
4) Radiations of organism into new habitats
5) Changes in ecosystem
6) Changes in continental position
Above are mechanisms of selection, the environment, basically.
Mechanisms of evolution are; mutation, gene flow. genetic drift and most importantly for adaptive changes, natural selection
What causes mutation in plants?
Mutations are changes in the DNA sequence of a cell's genome and are caused by radiation, viruses, transposons and mutagenic chemicals, as well as errors that occur during meiosis or DNA replication.They can also be induced by the organism itself, by cellular processes such as hypermutation.
Mutation can result in several different types of change in DNA sequences; these can either have no effect, alter the product of a gene, or prevent the gene from functioning properly or completely. Studies in the fly Drosophila melanogaster suggest that if a mutation changes a protein produced by a gene, this will probably be harmful, with about 70 percent of these mutations having damaging effects, and the remainder being either neutral or weakly beneficial.Due to the damaging effects that mutations can have on cells, organisms have evolved mechanisms such as DNA repair to remove mutations.Therefore, the optimal mutation rate for a species is a trade-off between costs of a high mutation rate, such as deleterious mutations, and the metabolic costs of maintaining systems to reduce the mutation rate, such as DNA repair enzymes. Viruses that use RNA as their genetic material have rapid mutation rates,which can be an advantage since these viruses will evolve constantly and rapidly, and thus evade the defensive responses of e.g. the humanimmune system.
What is an example of cultural evolution?
Cultural evolution regards the changes and adaptations to a societies identity, sensitivities, perspectives, and behaviors over time. The transformation of closed societies to globalization is a major example of cultural evolution in action. Demographic changes and global migration are also another driving example of how cultures are rapidly adapting and evolving,
How old does evolution say the world is?
The theory of evolution describes the change in genetic material of a population of organisms over time. The theory of evolution has nothing to do with the age of the earth.
Scientists estimate the age of the earth to be around 4.5 billion years, based on radiometric dating of moon rocks.
What are the two main types of isolation?
That would be geographic isolation and reproductive isolation. Both could lead to speciation.
Who proposed the idea of survival of the fittest is a theory of evolution?
Charles Darwin. Also known as Darwin's Theory of Evolution.
How do fossils support the theory that the continents were once joined together?
The Continental drift theory posits that the shoreline of many continents were at one time interlocked. Through tectonic movement and axis shift, the continents have drifted apart as is evidenced by similar animal fossils on differing continents.
What is the molecule that's responsible for unity and diversity of life?
DNA is the molecule that is responsible for unity and diversity of life .
What did Francesco Redi do dealing with evolution?
Redi did an experiment seeing what maggots come from by putting meat into jars and left 1 open 1 covered with netting and one sealed the only one that didn't get maggots was the one that was sealed proving that maggots come from flies.
What absolute proof is there for the theory of evolution?
1: evolution has never been witnessed.
2: We in science are constantly trying to prove the theory of evolution with the theory that life self generated is a pool of amino acids and proteins by complete chance....so far all experiments to attempt to manufacture a self replicating DNA based Molecule have come to no result. there is some evidence supporting RNA based molecules though. Also if successful this would pose an interesting paradox about creation..being we Science created a self replicating molecule...it did not create itself as theory of evolution works.
3: Fossil record is incomplete, yes sure we share similar bone structures to other animals etc.. but there is no defined developmental line of slight mutation per generation to warrant it being evidence for the time being, but it is getting stronger.
Now I am not even saying Evolution is incorrect. I'm being very open minded.
In fact, I think if you were to ask Richard Dawkins (the prince of evolution) he would say similar and he has:
Dawkins stated that "evolution has been observed. It's just that it hasn't been observed while it's happening." He added that "it is rather like a detective coming on a murder after the scene... the detective hasn't actually seen the murder take place, of course. But what you do see is a massive clue ... Huge quantities of circumstantial evidence. It might as well be spelled out in words of English."
Circumstantial for the moment.
Remember I am answering the question at hand....."Absolute Proof?"
There is no absolute proof.
The theory has a lot evidence in its favor and is the leading idea behind the how did we get here? but it is not absolute.
Definition of Evolution
There seems to be some confusion about what exactly evolution is. Now, when most people say 'evolution' they are referring to Macro-evolution (or speciation), which is the process of one animal slowly changing into another animal. People also tend to refer to Micro-evolution (or adaptation) when trying to prove Macro-evolution but they are two separate processes.
Macro-evolution requires the addition of new genetic material as well as mutations to genetic material in order to bring about enough change to be considered. To be clear, a genetic mutation is the removal of, or change to present genetic material.
Micro-evolution is essentially genetic variation in a species due to genetic mutation. No one argues against Micro-evolution because it is clearly evident. Look at all the different breeds of dogs (or finches) there are today. But there is a limit to how much information you can breed out of dog (or finch) DNA before the animal becomes so unhealthy that it is either unable to reproduce or cannot survive long enough to reproduce.
Macro-evolution, on the other hand, is a theory based on speculation that there is no intelligent designer that created the universe and life, therefore it must have arisen by natural causes. This theory postulates that natural adaptations seen in animals today can eventually lead to the establishment of new species of animals, if given enough time. There is no experiment using the scientific method that can be used to prove that the theory of evolution is correct. That is unless you conduct an experiment over millions of years, but it still would not prove that evolution had occurred in the past.
So the short answer is:
'There is abundant proof of Micro-evolution, but no proof of Macro-evolution.'
For more information and discussion of this topic visit the Discussion Page.
How can variation in offspring be beneficial to survival of a population?
If every organism in a population had the same genes, then they would all be affected in exactly the same way by any outside factors from the environment.
This means that if some factor resulted in those genes being lethal or not suited to survival, the entire population would suffer in exactly the same way: they would all die and the species becomes extinct. The idiom "all your eggs in one basket" comes to mind when describing such a situation.
Variation allows for some organisms to survive different factors. If some genes were lethal or not suited for survival, then only the affected members die and the majority (or at least enough to ensure continuation) of the population survive.
Traits, which we define as visible aspects of an organism (known as the organism's phenotype) , are coded for by an organisms DNA and are expressed through the proteins that that DNA codes for. Here's the indepth version:
Every living organism on this earth has DNA (or in some bacteria, RNA). These strands of DNA are made of nucleic bases (adenine, thymine, cytosine, and guanine), phosphates, and sugars. These components form DNA into the double helix shape we associate with DNA (the twisted ladder shape.) The nucleic bases are held together in the middle of the two strands by weak hydrogen bonds. This is what we know contemporarily as a strand of DNA.
Strands upon strands of DNA are then packaged together (with protein formations generally called histones) to form what we know as the chromosome. DNA must be packaged this way so that the extremely long strands of DNA can be easily moved during sexual (or asexual) reproduction. But that's another topic.
The expression of "traits" can be traced back specifically to the order of nucleic bases in the DNA, and the proteins those bases code for. Here's how it works.
Let Organism A have a certain part of their DNA that reads
ATCAGCATAGCAUAG
These nucleic bases would then be paired with their complement bases on the other strand of DNA. But let us then say that the cells in Organism A want to express this trait. A process known as transcription and translation must occur.
First, the DNA is "unzipped" by an enzyme. Then, another enzyme moves along the DNA and lays down a "primer strand" (this enzyme, fittingly, is called primase) of RNA. RNA is just like DNA, except that in RNA, Thymine is not existant and a particle known as ribose is present. There are different types of RNA, but in this instance, mRNA (messenger RNA) is used. Another enzyme will move along the DNA-mRNA strands, inserting completmentary bases on the RNA. But since thymine is not expressed in RNA, Adenine must match with another base (only present in RNA) called uracil. The above code would be expressed like this in mRNA:
UAGUCGUAUCGUAUC
(NOTE: Adenine always binds with Thymine or Uracil, Cytosine always binds with Guanine)
This particular strand of mRNA is almost ready to leave the nucleus to be translated. First, a 5' cap and poly-A tail must be added to either end of the strand to protect it during transport.
This mRNA is then taken to ribosomes in the cell, which are located outside the nucleus. This step is called translation.
When the mRNA arrives at the ribosome, it begins to slide "through" the ribosome. Now, it is important to know that DNA and mRNA is read in groups of three. Every three bases, known as a codon, has a matching anticodon. These mRNA codons will feed through the ribosome, and according to the particular order of the bases, a molecule called tRNA (transport RNA) will arrive at the ribosome with the matching anticodons. Attatched to these tRNA structures are the matching anticodons and an amino acid.
The above strand would then match with these anticodons. Note how the anticodons resemble the original DNA.
AUCAGCAUAGCAUAG
The only difference is the fact that thymine is replaced by Uracil. The amino acids that are brought to the ribosome by tRNA then bind to each other through peptide bonds, eventually forming a polypeptide chain (the beginnings of a protein).
Thus, we can see how DNA codes for RNA which then codes for specific amino acids. Scientists have developed a table that can determine which aminos are coded for according to the order of the bases.
So, the need to know is this: DNA codes for mRNA in a process called transcription. Then, that mRNA is translated at ribosomes. The anticodons that bind to the mRNA determine which proteins are made. Ultimately, those proteins express traits based on the function of the protein.
DNA codes for mRNA--> mRNA codes for tRNA anticodons---> the specific order of the assembled amino acids determines their function, thus expressing a trait.
What is the definition of positive mutation?
Last Answer: "Never! When would it be positive? It's a DEFORMATION!!!"
That's incorrect. Without mutations, evolution could never occur. For example:
Imagine a bird with a very small mouth. The seeds it eats are very large, and many birds die of starvation. Because of a mutation, one bird's mouth is larger than any other's, and it ends up surviving, passing on that "deformed" gene to its offspring who also survive because of their large mouths.
That is just one example of how a mutation can lead to positive evolutionary changes.
Origin of man on biblical theory?
Well there's the big bang theory then evolution which is scientifically proven also various religious beliefs regarding how man and the world was created for example christians belive that god created the world and mankind
Why is Darwin more famous than Wallace in the explanation of evolution?
The reason the focus, or major credit goes to Darwin is, though they both realized the principles of evolution, Wallace's presentation was little more than the realization. Darwin had had the realization and spent almost twenty years documenting and exploring the relations and complexities of said theory. Wallace himself had no difficulty with Darwin receiving the majority of the credit. Wallace had sent Darwin his paper on the topic, which kind of shocked Darwin that some one else might scoop his idea, he decided to present his idea to the Royal Society, and when he did so, he presented at the same time Wallace's paper, a very gracious thing to do on Darwins part. Wallace was at the time totally unaware of what was happening and only learned after the fact that he was presented to the Royal Society as co-discoverer of, The Theory Of Evolution By Natural Selection.
Which is an example of vestigial structure?
Most of the "higher evolved" animals I can think of have a vestigial structure or two. The most common example given is of the vestigial leg structures that can be found in the back of whales. Ostriches can't fly so i think their wings are considered vestigial. Humans have a vestigial tail bone.
What evidence is used to support evolutionary theory?
Darwin noted similarities in species far removed from each other. His observations of finch beaks on the Galapagos Islands was one key piece of information helping him formulate his theory. Darwin did not realize these birds were finches to begin with. Only after he brought specimens back to England did an ornithologist point out what his birds were. The adaptations in beaks was one of the things that helped him piece together his theory.
Other evidence existed in the numerous fossils Darwin accumulated. These fossils showed gradual changes in species over vast periods of time. Birds and reptiles are diapsids, whereas all mammals (including humans) are synapsids. Darwin conjectured some fossil might exist to show a link between reptiles and birds, and that fossil was Archeopteryx. Since then we have found numerous other examples of transitions between species.
Yet more evidence is found in genetic similarities. On the basis of their anatomy organisms can be grouped into tree like structures of nested hierarchies. These nested hierarchies are evidence of common ancestry. Any other classification system would constitute evidence against common ancestry, and hence against evolution. However, genetic analysis produces identical overlapping tree structures. This is considered excellent evidence for the soundness of the foundational theory of biology.
