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Evolution
The scientific theory according to which populations change gradually through a process of natural selection.
5,264 Questions
What percentage of scientists accept the validity of the theory of evolution?
In the relevant fields (biologists), 99.99% accept evolution.
In science generally, the figure is slightly lower, around 98%. Those that disagree usually do so on religious bases, not scientific ones.
Charles Darwin called the ability of an organism to survive and reproduce is its environment?
Charles Darwin referred to this ability as "natural selection." It is the process by which certain traits or characteristics that help an organism survive and reproduce in its environment become more common in a population over time. Natural selection is a key mechanism of evolution.
How quickly does evolution occur?
The rate of evolution can vary greatly depending on the species and the environmental pressures they face. Some organisms can evolve relatively quickly, such as bacteria that develop resistance to antibiotics within a few years. In contrast, larger and more complex organisms like humans or elephants may evolve over much longer timescales of thousands to millions of years.
What is the differences between geographic isolation temporal isolation and behavioral isolation?
Geographic isolation: a population is separated by distance or some kind of barrier so the members of the population can't interbreed with the main population.
Temporal isolation: Two species that breed at different times of the day, season, or year cannot mix their gametes.
Behavioral Isolation. Species-specific signals and elaborate behavioral patterns are used by closely related species to insure contact with the proper mate. Birds, mammals, and insects have pre-mating rituals that attract the proper mate. These signals can be chemical or physical in nature. Other organisms pay little or no attention to these behaviors or scents.
What support is there for evolution?
There is much support for evolution, because there is a lot of evidence. Almost all the scientific community has accepted evolution as fact and there is no longer much dispute about whether it is true.
Evidence for Evolution:-In the fossil recordRemains of animals and plants found in sedimentary rock deposits give us an indisputable record of past changes through vast periods of time. This evidence attests to the fact that there has been a tremendous variety of living things. Some extinct species had traits that were transitional between major groups of organisms. Their existence confirms that species are not fixed but can evolve into other species over time.
The evidence also shows that what have appeared to be gaps in the fossil record are due to incomplete data collection. The more that we learn about the evolution of specific species lines, the more that these so-called gaps or "missing links in the chain of evolution" are filled with transitional fossil specimens. One of the first of these gaps to be filled was between small bipedal dinosaurs and birds. Just two years after Darwin published On the Origin of Species, a 150-145 million year old fossil of Archaeopteryx was found in southern Germany. It had jaws with teeth and a long bony tail like dinosaurs, broad wings and feathers like birds, and skeletal features of both. This discovery verified the assumption that birds had reptilian ancestors.
GeneticsLiving things on earth are fundamentally similar in the way that their basic anatomical structures develop and in their chemical compositions. No matter whether they are simple single-celled protozoa or highly complex organisms with billions of cells, they all begin as single cells that reproduce themselves by similar division processes. After a limited life span, they also all grow old and die.
All living things on earth share the ability to create complex molecules out of carbon and a few other elements. In fact, 99% of the proteins, carbohydrates, fats, and other molecules of living things are made from only 6 of the 92 most common elements. This is not a mere coincidence.
All plants and animals receive their specific characteristics from their parents by inheriting particular combinations of genes. Molecular biologists have discovered that genes are, in fact, segments of DNA molecules in our cells.
Segments of DNA contain chemically coded recipes for creating proteins by linking together particular amino acids in specific sequences.
All of the tens of thousands of types of proteins in living things are made of only 20 kinds of amino acids. Despite the great diversity of life on our planet, the simple language of the DNA code is the same for all living things. This is evidence of the fundamental molecular unity of life.
In addition to molecular similarities, most living things are alike in that they either get the energy needed for growth, repair, and reproduction directly from sunlight, by photosynthesis or they get it indirectly by consuming green plants and other organisms that eat plants.
AnatomyMany groups of species share the same types of body structures because they inherited them from a common ancestor that had them. This is the case with the vertebrates which are the animals that have internal skeletons. The arms of humans, the forelegs of dogs and cats, the wings of birds, and the flippers of whales and seals all have the same types of bones (humerus, radius, and ulna) because they have retained these traits of their shared common ancient vertebrate ancestor.
All of these major chemical and anatomical similarities between living things can be most logically accounted for by assuming that they either share a common ancestry or they came into existence as a result of similar natural processes. These facts make it difficult to accept a theory of special and independent creation of different species.
Geographic DistributionAnother clue to patterns of past evolution is found in the natural geographic distribution of related species. It is clear that major isolated land areas and island groups often evolved their own distinct plant and animal communities. For instance, before humans arrived 60-40,000 years ago, Australia had more than 100 species of kangaroos, koalas, and other marsupials but none of the more advanced terrestrial placental mammals such as dogs, cats, bears, horses. Land mammals were entirely absent from the even more isolated islands that make up Hawaii and New Zealand. Each of these places had a great number of plant, insect, and bird species that were found nowhere else in the world. The most likely explanation for the existence of Australia's, New Zealand's, and Hawaii's mostly unique biotic environments is that the life forms in these areas have been evolving in isolation from the rest of the world for millions of years.
Genetic Changes Over GenerationsThe earth's environments are constantly changing, usually in subtle and complex ways. When the changes are so great as to go beyond what most members of a population of organisms can tolerate, widespread death occurs. As Charles Darwin observed, however, not all individuals always perish. Fortunately, natural populations have genetic diversity. Those individuals whose characteristics allow them to survive an environmental crisis likely will be the only ones able to reproduce. Subsequently, their traits will be more common in the next generation--evolution of the population will have occurred.
This process of natural selection resulting in evolution can be easily demonstrated over a 24 hour period in a laboratory Petri dish of bacteria living in a nutrient medium. When a lethal dose of antibiotic is added, there will be a mass die-off. However, a few of the bacteria usually are immune and survive. The next generation is mostly immune because they have inherited immunity from the survivors. That is the case with the purple bacteria in the Petri dishes shown below--the bacteria population has evolved.
This same phenomenon of bacteria evolution speeded up by human actions occurs in our own bodies at times when an antibiotic drug is unable to completely eliminate a bacterial infection. That is the reason that medical doctors are sometimes hesitant to recommend an antibiotic for their patients and insist that the full dosage be used even if the symptoms of illness go away. They do not want to allow any potentially antibiotic resistant bacteria to survive.
People have developed many new varieties of plants and animals by selective breeding. This process is similar to the bacteria experiment described above. Selection of specimens to breed based on particular traits is, in effect, changing the environment for the population. Those individuals lacking the desirable characteristics are not allowed to breed. Therefore, the following generations more commonly have the desired traits.
Species that mature and reproduce large numbers in a short amount of time have a potential for very fast evolutionary changes. Insects and microorganisms often evolve at such rapid rates that our actions to combat them quickly lose their effectiveness. We must constantly develop new pesticides, antibiotics, and other measures in an ever escalating biological arms race with these creatures. Unfortunately, there are a few kinds of insects and microbes that are now significantly or completely resistant to our counter measures, and some of these species are responsible for devastating crop losses and deadly diseases.
If evolution has occurred, there should be many anatomical similarities among varieties and species that have diverged from a common ancestor. Those species with the most recent common ancestor should share the most traits. For instance, the many anatomical similarities of wolves, dogs, and other members of the genus Canis are due to the fact that they are descended from the same ancient canine species and still share 99.8% of their genes. Wolves and dogs also share similarities with foxes, indicating a slightly more distant ancestor with them.
Yes, evolution has been observed in numerous studies and experiments. Examples include the development of antibiotic resistance in bacteria, changes in beak size of Galapagos finches, and the coloration of peppered moths in response to environmental changes.
What is the mechanism for determining evolution of life?
The mechanism for determining the evolution of life is natural selection, proposed by Charles Darwin. Natural selection refers to the process by which organisms with advantageous traits for survival and reproduction are more likely to pass on their genes to the next generation, leading to the gradual change in populations over time. Genetic mutations also play a key role in introducing new variations that can contribute to evolution.
Why does scientific evidence support scientific theories?
Scientific evidence supports scientific theories through empirical observations, experiments, and data analysis that consistently confirm the predictions and explanations of the theories. Theories are continuously tested and revised based on new evidence, leading to a more refined and accurate understanding of the natural world. Overall, the robustness and validity of scientific theories are demonstrated through the process of evidence accumulation and verification by multiple independent researchers.
Who came up up with your method for classifying organisms?
Carl Linnaeus is credited with developing the method for classifying organisms, known as the Linnaean system of taxonomy. He introduced the hierarchical classification system based on shared physical characteristics of organisms.
What are the doctrines of evolution?
There are no ' doctrines ' of evolution. Evolution, the change in allele frequency over time in a population of organisms, is fact. The theory of evolution by natural selection explains, to a great degree, this fact. The theory is supported by mountains of evidence, from fossils to molecular genetics. Science does not have doctrines.
What is evolutionary competition?
Evolutionary competition is the process in which organisms compete for limited resources, such as food, habitat, and mates, in order to survive and reproduce. This competition drives natural selection, where individuals with traits that best suit their environment are more likely to pass on their genes to the next generation. Over time, this can lead to the evolution of characteristics that enhance an organism's ability to compete and succeed in their environment.
Instead of using a family tree scientists use a tree to track the evolutionary history of a species?
Yes, scientists use a phylogenetic tree to depict the evolutionary relationships between different species. This tree shows how species are related through common ancestors and provides a visual representation of the evolutionary history of a group of organisms. The branches on the tree represent the evolutionary split points where new species have arisen.
How can mutation affect evolution?
Mutations can introduce new genetic variations that may be beneficial, neutral, or harmful to an organism's survival and reproduction. Beneficial mutations can provide an advantage in certain environments, leading to an increased likelihood of those traits being passed on to future generations through natural selection, which can drive evolutionary change. Harmful mutations may be selected against and reduced in frequency within a population over time.
Is there no evidence of a common ancestor?
There is ample evidence of a common ancestor for all life on Earth, known as the Last Universal Common Ancestor (LUCA). This is supported by various lines of evidence, including genetic similarities, shared biochemical pathways, and the universal presence of certain biomolecules across diverse species.
Evolution is as logical as you can get. Supported by concrete evidence, corroborated by scientists worldwide, and put through the scientific method time and time again... it does not deviate into a subjective opinion. Those who don't believe the theory of evolution is logical clearly do not understand evolution.
The frequencies of alleles and genotypes remain constant from generation to generation unless?
Unless there are factors such as mutation, genetic drift, gene flow, or natural selection that can cause changes in allele frequencies within a population. This concept is known as the Hardy-Weinberg equilibrium, which describes the conditions under which allele and genotype frequencies remain stable over time in a population.
Which of the following resulted from a genetic variation that was favored by natural selection?
The development of antibiotic resistance in bacteria is a result of genetic variation that was favored by natural selection. Bacteria that had a mutation making them resistant to antibiotics were able to survive and reproduce, passing on this trait to future generations. Over time, this led to the prevalence of antibiotic-resistant strains in bacterial populations.
What does the main trunk at the bottom of a phylogenetic tree represent?
The main trunk at the bottom of a phylogenetic tree represents the common ancestor from which all the species or groups included in the tree descended. It is the starting point from which the branches representing different species or groups diverge.
How does the geologic time scale help support the theory of evolution?
The geologic time scale provides a framework for understanding the sequence of events in Earth's history, allowing scientists to study the fossil record and track the evolution of organisms over millions of years. By correlating the age of rocks with the appearance of different species in the fossil record, the geologic time scale helps support the idea of gradual change and common ancestry proposed by the theory of evolution.
Who was the First to propose a theory of evolution?
Charles Darwin is credited with proposing the theory of evolution through natural selection in his book "On the Origin of Species" published in 1859.
What is a rapid evolution of species that comes about by the mutation of a few genes?
An example of very rapid speciation could be the process of polyploidy, which is often observed in plants, but also known to occur in animals. This is the uncharacteristic (at least in that particular species) duplication of all chromosomes in offspring. Occasionally, such a whole-genome duplication can cause an inability to interbreed with organisms from the parental stock, meaning that speciation has occurred. This form of speciation would be almost impossible to occur in species of sexually reproducing animals, unless the same whole-genome duplication occurred more frequently, or the organism in question were able to self-fertilize (some hermaphrodite organisms may be able to do so).
Of course any set of mutations that significantly alters the physiology of offspring without inhibiting its ability to reproduce could be categorized in the same way.
What is heavily influenced by the theory of evolution?
Many fields are influenced by the theory of evolution, including biology, psychology, anthropology, and medicine. Evolutionary theory helps explain the development and diversity of living organisms, the behavior of species, and the emergence of traits that provide advantages for survival and reproduction. It has also influenced concepts such as natural selection, adaptation, and genetic variation.
Generation-to-generation change in allele frequencies in a population is?
The term used to describe the generation-to-generation change in allele frequencies of a population is simply evolution.
Simple answer for a complicated-looking question. ;) Hope this helps.
Which type of natural selection tends to prevent evolution?
Stabilizing selection tends to prevent evolution as it favors the intermediate phenotype and reduces genetic variation in a population. This can lead to the maintenance of a stable population with limited change over time.
Does evidence prove or disprove evolution?
Law and math prove things. Science supports tentative ( more or less ) explanations of natural phenomenon with evidence.
The evidence overwhelmingly supports evolutionary theory.
PS Evolution itself is a observed and observable fact.
