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Evolution
The scientific theory according to which populations change gradually through a process of natural selection.
5,264 Questions
What are some common misrepresentations of evolutionary theory?
That it is a random process when natural selection is involved, that the process is directed and plans for future evolutionary changes, that the process is always very slow, that the process reaches a plateau and goes no further and, finally, that man is somehow not subject to evolutionary processes, at least his mind is not so subjected.
What is the role of genes and the environment in evolution?
Genes play a critical role in evolution by influencing an organism's traits and characteristics. Changes in genes over generations (mutations, genetic drift, etc.) can lead to new variations that may be advantageous in certain environments, thus driving evolution. The environment also plays a significant role by selecting for certain traits that enhance an organism's survival and reproduction, shaping the direction of evolution.
What morphological evidence is there for common descent?
Carl Linnaeus was the first to devise a consistent, comprehensive system of classification for animals. He noticed that life seems to be organized in a set of nested hierarchies: groups within groups, within groups, each group having the basal characteristics of the larger group, as well as a set of characteristics uniquely identifying that group within the larger group. His only point of reference was the morphology of living things. His findings, although he was basically a creationist, were key in developing subsequent theories of evolution. Today, we know that these nested hierarchies do not just apply to the morphological characteristics of life, but to the genetic and behavioural as well.
When was Charles dawins theory on evolution published?
24 November 1859
On The Origin Of Species By Means Of Natural Selection Or The Preservation Of Favored Races In The Struggle For Life
Races means species.
What describes the transformation hypothesis of evolution?
Answer 1
Transformation hypothesis:
Evolution is the change in allele frequency over time in a population of organisms.
This is an observed and observable fact.
Natural selection is the nonrandom survival and reproductive success of randomly varying organisms. This is a theory, not a hypothesis.
Natural selection is the adaptive change driver of evolution by adapting individuals to their environment so they are reproductively more successful than their con-specifics and their genes are more frequently represented in the next generations of the population; evolution.
Answer 2
To my knowledge, there is no such thing as the "transformation hypothesis of evolution". Especially note that evolution does not describe any kind of transformation, but a process of undirected, gradual change over generations. Using the term 'transformation' might instil inaccurate ideas about what evolution is, and what evolutionary theory states about it.
Why did Darwin believe organisims evolved using natural selection instead of required traits?
One of the strongest reasons he had for thinking natural selection was the driving force of evolution in fact he started his book with this concept, was artificial selection. Breeders had long know that traits were heritable and they could select for the traits they wanted by just mating the favored organisms. From this example Darwin knew that acquired traits were neither heritable or selectable.
What is one factor that affects natural selection and artificial selection?
Variation in the organisms under selection. In both artificial selection and natural selection there must be heritable variations that have the possibility of being in the case of artificial selection what the selector wants in the organism and in thje case of natural selection survivability and reproductive advantages.
How does molecular evidence occur?
Take the cytochrome C electron shuttle in the electron transport chain and see how it is highly conserved in form and function among a wide variety of eukaryotes. That is molecular evidence for the relatedness of widely disparate organisms.
Why are heritable mutations important for evolution?
Genetic mutation is one of the mechanisms that provides the reproductive variation that drives evolution. It deactivates alleles, and introduces new alleles into the genome though insertion into, deletion from, duplication of, point mutation of and frameshifts of existing sequences.
Answer: Heritable mutations were postulated as a possible source of genetic variation to ennable natural selection to have material to work changes in organisms. This mechanism of variation was seen as vital to evolution from the time that the implications of genetics as discovered by Mendel was realised.
Unfortunately for evolution, there has never been discovered a single example of a mutation adding new genetic information (although occasionally mutations are beneficial, which is not always the same thing). Richard Dawkins was asked about this very issue in an interview and could not provide one single example of an information-adding mutation. This is no small problem for their is a staggering amount of new information necessary to be written into the DNA to change a microbe into a microbiologist (for example).
Actually mutations are universally shown to be causing genetic degradation in all multicellular life, In humans this is believed conservatively to amount to 100 new mutations per person per generation. Mostly these mutations are small such that natural selection does not 'see' them to eliminate them and so they accumulate in the genome of mankind like rust on a car. The rate of mutation which we observe today would lead to the extinction of the entire human race in a much shorter period of time than is commonly realised. This knowledge led one evolutionary geneticist to ask 'why are we not all dead already?' It is precisely because these deleterious mutations are inherited and retained in the genome and not selected against that the problem arises.
According to geneticist Dr John Sandford, from Cornell University, there is close to unanimous agreement among geneticists regarding human genetic degradation, even though most continue to believe in evolution. Sandford cites recent papers by geneticists such as Muller, Noal, Kondrashov, Nachmann/Crowell, Walker/Keightley, Crow, Lynch et al, Howell, Loewe and Sandford himself (in print). Sandford highlights Loewe's contention in a paper published in 2010 (in The Proceedings of the National Academy of Science) that there is a fitness decline of between 3-5% per generation. Sandford himself from his modeling believes it is not as dire. Another geneticist, Robert Carter, points out that the key issue is not that there are no beneficial mutations but that the deleterious ones are so subtle that they are not selected against, and so the net effect is downhill.
What role does Surface area and volume play in evolution?
S2/V3
Sets the size of cells for one thing as the volume can not grow too greatly over the surface area of a cell as the cell would not be able to import nutrients and export wastes.
It isn't. It is one of the truest things you can ever find.
Science has proven evolution time and time again. We have even witnessed some speciesevolvingbefore our very eyes.
Some religious organisations are still in denial,clingingonto ancient traditions that are dying in the modern world and no longer fit into modern society.
Science has provided facts and proof. Whereas with religion, it just says so in a book. If the bible is true because it's a book, then by that logic, Harry Potter is true too.
When the mean value of variation is selected for what type of selection results?
When the mean value of variation is selected, it typically results in stabilizing selection. This type of selection favors individuals with traits that are close to the average, reducing the prevalence of extreme phenotypes. As a result, the population tends to maintain its average traits over time, leading to reduced variation and increased uniformity within the population.
How long ago did the modern human species evolve?
This theoretical question has highly differing answers. Some archaeologists may argue that the modern human species evolved around 2.3 million years ago, while others believe differently.
Are there complicated links between microevolution and macroevolution?
Microevolution is small evolutionary changes. Macroevolution is change above the specie level. Biologists debate if this process even exists. Some say they are fundamentally the same thing. It seems that macroevolution is the evolution of evolution. That sounds complicated.
What are the five main points of Darwin's theory of natural selection?
- Variation: Individuals within a species exhibit variation in traits.
- Competition: Resources are limited, leading to competition for survival.
- Survival of the fittest: Individuals with advantageous traits are more likely to survive and reproduce.
- Heritability: Traits that confer a survival advantage are passed on to offspring.
- Gradual change: Over time, the population evolves as advantageous traits become more common.
Is gradualism a slow continuous process?
Yes, gradualism is a concept that suggests change happens slowly and steadily over time, without sudden shifts or abrupt changes. It refers to a continuous process of evolution or transformation.
What is the accumulation of differences between groups that lead to formation of new species?
This is called genetic divergence. Over time, accumulated genetic differences between populations can lead to the formation of new species through a process known as speciation. This can occur through various mechanisms such as natural selection, genetic drift, and isolation.
What the differences between natural selection and sexual selection?
Sexual selection is a subset of natural selection that is strictly " concerned " with reproductive success. You will see organisms adapted in physiology and behavior to attract mates of the other sex with these adaptions contravening survival possibilities. Take the classic peacock example. The peacock is selected by the peahen on the basis of his tail display regardless of how such a heavy and survival risking adaption leaves the peacock open to predation. Remember, fitness is reproductive fitness and if the peacock can father most of the progeny of his local population at mating time because his tail attracts more females then what matter if he dies young.
Does evolution mean to change gradually over time?
Yes, evolution refers to the process by which organisms change over successive generations through genetic variation and natural selection. This change can occur gradually over long periods of time, leading to the diversity of life on Earth today.
That evolution by natural selection is occurring in this cactus population?
To determine if evolution by natural selection is occurring in a cactus population, you would need to observe changes in the heritable traits of the cacti over time, caused by differences in survival and reproduction. This would indicate that certain traits are being favored, leading to a shift in the genetic makeup of the population.
How do scientist think first plants appeared on earth?
They think that the first algae developed as a result of endosymbiosis between primitive eukaryotic cells and cyanobacteria. A similar phenomenon can be seen in amoebae of the species Paulinella chromatophora, with which modern cyanobacteria have formed an endosymbiotic relationship.
When distantly related life form develop similar trits is it convergent evolution?
Yes, when distantly related life forms independently evolve similar traits to adapt to similar environmental pressures, it is called convergent evolution. This phenomenon demonstrates the power of natural selection in shaping organisms to their environments.
Why was the evolution of spores important to the success of life on land?
Spores allowed plants to reproduce and disperse in a dry environment, enabling them to colonize land. Spores served as a protective mechanism against desiccation and helped plants survive in diverse habitats. This adaptation was essential for the transition of plants from aquatic to terrestrial environments.
What did Darwin mean when he said that natural selection works on existing variation?
Natural selection is the differential reproductive success of genomic variation. But for differing variants to be able to compete reproductively, such variants must exist in the first place. Reproduction causes such variants to come into existence.
Why was Lamarck's theory of evolution incorrect?
Lamarck's theory of evolution, known as Lamarckism, proposed that organisms could pass on traits acquired during their lifetime to their offspring, such as a giraffe stretching its neck to reach higher leaves and then having offspring with longer necks. This idea was incorrect because it lacks genetic basis; traits are inherited through genes, not acquired characteristics. Modern genetics and Darwinian natural selection provide a more robust explanation for evolution, emphasizing heritable variations that arise through mutations rather than acquired traits.
