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Evolution Explained The most basic concept is that living things change in time. These changes can help the organism to survive or reproduce, or be more adapted to its environment. Scientists have used the new genetics research to explain how evolution operates. They also utilized physical science to determine the amount of energy needed to create these changes. Natural Selection To allow evolution to occur organisms must be able to reproduce and pass their genetic characteristics onto the next generation. This is the process of natural selection, sometimes referred to as “survival of the best.” However, the phrase “fittest” is often misleading as it implies that only the strongest or fastest organisms can survive and reproduce. In reality, the most species that are well-adapted are able to best adapt to the conditions in which they live. Moreover, environmental conditions can change rapidly and if a group is not well-adapted, it will not be able to sustain itself, causing it to shrink, or even extinct. The most important element of evolutionary change is natural selection. This happens when advantageous phenotypic traits are more common in a given population over time, which leads to the development of new species. This process is driven by the genetic variation that is heritable of organisms that result from mutation and sexual reproduction and the competition for scarce resources. Selective agents may refer to any force in the environment which favors or discourages certain characteristics. These forces can be biological, such as predators, or physical, for instance, temperature. Over time populations exposed to various agents of selection can develop different that they no longer breed together and are considered separate species. While the idea of natural selection is straightforward, it is not always clear-cut. The misconceptions about the process are common even among scientists and educators. Surveys have shown that students' understanding levels of evolution are only weakly associated with their level of acceptance of the theory (see the references). Brandon's definition of selection is limited to differential reproduction, and does not include inheritance. But a number of authors, including Havstad (2011) has claimed that a broad concept of selection that encompasses the entire cycle of Darwin's process is sufficient to explain both adaptation and speciation. Additionally there are a variety of instances where a trait increases its proportion within a population but does not alter the rate at which people with the trait reproduce. see this site are not necessarily classified in the strict sense of natural selection, but they could still be in line with Lewontin's requirements for a mechanism such as this to function. For 에볼루션 무료체험 with a particular trait might have more offspring than those without it. Genetic Variation Genetic variation refers to the differences in the sequences of genes that exist between members of a species. Natural selection is one of the major forces driving evolution. Variation can be caused by mutations or the normal process by which DNA is rearranged in cell division (genetic Recombination). Different gene variants may result in a variety of traits like eye colour, fur type or the capacity to adapt to changing environmental conditions. If a trait is characterized by an advantage, it is more likely to be passed down to future generations. This is known as a selective advantage. A particular type of heritable change is phenotypic plasticity, which allows individuals to alter their appearance and behaviour in response to environmental or stress. These changes could allow them to better survive in a new habitat or take advantage of an opportunity, for example by increasing the length of their fur to protect against the cold or changing color to blend in with a particular surface. These phenotypic changes, however, don't necessarily alter the genotype and thus cannot be considered to have contributed to evolution. Heritable variation is essential for evolution because it enables adapting to changing environments. It also permits natural selection to function in a way that makes it more likely that individuals will be replaced in a population by those with favourable characteristics for the environment in which they live. In some cases however the rate of variation transmission to the next generation might not be enough for natural evolution to keep up. Many harmful traits, such as genetic disease persist in populations, despite their negative effects. This is due to a phenomenon referred to as diminished penetrance. This means that people with the disease-related variant of the gene don't show symptoms or signs of the condition. Other causes include gene-by- environment interactions and non-genetic factors like lifestyle, diet, and exposure to chemicals. To understand why certain undesirable traits aren't eliminated through natural selection, it is important to understand how genetic variation influences evolution. Recent studies have demonstrated that genome-wide associations that focus on common variations do not reflect the full picture of disease susceptibility and that rare variants account for the majority of heritability. Further studies using sequencing are required to catalogue rare variants across worldwide populations and determine their effects on health, including the influence of gene-by-environment interactions. Environmental Changes The environment can influence species by altering their environment. This concept is illustrated by the famous story of the peppered mops. The white-bodied mops, that were prevalent in urban areas in which coal smoke had darkened tree barks were easily prey for predators, while their darker-bodied counterparts thrived under these new circumstances. The opposite is also true: environmental change can influence species' ability to adapt to changes they face. The human activities cause global environmental change and their effects are irreversible. These changes are affecting global biodiversity and ecosystem function. Additionally, they are presenting significant health hazards to humanity especially in low-income countries, because of pollution of water, air, soil and food. For instance an example, the growing use of coal by countries in the developing world, such as India contributes to climate change, and raises levels of air pollution, which threaten human life expectancy. Furthermore, human populations are using up the world's finite resources at a rapid rate. This increases the risk that many people are suffering from nutritional deficiencies and lack access to safe drinking water. The impacts of human-driven changes to the environment on evolutionary outcomes is complex. Microevolutionary changes will likely alter the fitness landscape of an organism. These changes may also alter the relationship between a certain characteristic and its environment. Nomoto et. al. have demonstrated, for example that environmental factors like climate, and competition, can alter the characteristics of a plant and shift its choice away from its previous optimal match. It is therefore important to know the way these changes affect the microevolutionary response of our time, and how this information can be used to predict the fate of natural populations in the Anthropocene period. This is vital, since the environmental changes caused by humans directly impact conservation efforts, as well as our health and survival. Therefore, it is essential to continue research on the interplay between human-driven environmental changes and evolutionary processes at an international scale. The Big Bang There are a myriad of theories regarding the universe's origin and expansion. However, none of them is as widely accepted as the Big Bang theory, which has become a staple in the science classroom. The theory explains a wide range of observed phenomena, including the abundance of light elements, cosmic microwave background radiation as well as the vast-scale structure of the Universe. The simplest version of the Big Bang Theory describes how the universe started 13.8 billion years ago in an unimaginably hot and dense cauldron of energy that has been expanding ever since. The expansion has led to all that is now in existence, including the Earth and its inhabitants. The Big Bang theory is supported by a variety of evidence. This includes the fact that we perceive the universe as flat as well as the thermal and kinetic energy of its particles, the temperature fluctuations of the cosmic microwave background radiation, and the relative abundances and densities of heavy and lighter elements in the Universe. The Big Bang theory is also well-suited to the data gathered by astronomical telescopes, particle accelerators, and high-energy states. In the early years of the 20th century the Big Bang was a minority opinion among physicists. Fred Hoyle publicly criticized it in 1949. But, following World War II, observational data began to surface which tipped the scales favor of the Big Bang. In 1964, Arno Penzias and Robert Wilson were able to discover the cosmic microwave background radiation, an omnidirectional sign in the microwave band that is the result of the expansion of the Universe over time. The discovery of this ionized radiation, that has a spectrum that is consistent with a blackbody at about 2.725 K, was a major turning point in the Big Bang theory and tipped the balance in its favor over the competing Steady State model. The Big Bang is an important part of “The Big Bang Theory,” a popular TV show. In the show, Sheldon and Leonard make use of this theory to explain various phenomena and observations, including their study of how peanut butter and jelly get mixed together.