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Evolution Explained The most fundamental idea is that all living things alter over time These changes can aid the organism in its survival or reproduce or be more adaptable to its environment Scientists have utilized the new science of genetics to explain how evolution operates They also have used physics to calculate the amount of energy needed to cause these changes Natural Selection To allow evolution to occur organisms need to be able to reproduce and pass their genetic characteristics onto the next generation Natural selection is sometimes called survival for the fittest However the phrase can be misleading as it implies that only the strongest or fastest organisms will survive and reproduce In reality the most species that are welladapted are the most able to adapt to the environment they live in Environmental conditions can change rapidly and if a population is not well adapted to the environment it will not be able to survive resulting in a population shrinking or even disappearing The most fundamental element of evolutionary change is natural selection This occurs when advantageous phenotypic traits are more prevalent in a particular population over time leading to the creation of new species This process is driven by the genetic variation that is heritable of living organisms resulting from mutation and sexual reproduction as well as the need to compete for scarce resources Selective agents can be any environmental force that favors or dissuades certain characteristics These forces can be biological like predators or physical for instance temperature As time passes populations exposed to various selective agents can evolve so differently that no longer breed together and are considered to be distinct species Natural selection is a simple concept but it can be difficult to comprehend The misconceptions about the process are widespread even among educators and scientists Studies have found a weak relationship between students knowledge of evolution and their acceptance of the theory For instance Brandons specific definition of selection relates only to differential reproduction and does not encompass replication or inheritance However several authors such as Havstad 2011 have argued that a capacious notion of selection that encompasses the entire cycle of Darwins process is sufficient to explain both adaptation and speciation There are instances when a trait increases in proportion within an entire population but not at the rate of reproduction These cases may not be classified as natural selection in the focused sense of the term but could still be in line with Lewontins requirements for a mechanism to function for instance when parents who have a certain trait produce more offspring than parents with it 무료에볼루션 is the difference in the sequences of genes between members of the same species It is this variation that facilitates natural selection which is one of the main forces driving evolution Variation can result from changes or the normal process through which DNA is rearranged during cell division genetic recombination Different genetic variants can lead to different traits such as eye color fur type eye color or the ability to adapt to adverse conditions in the environment If a trait is advantageous it will be more likely to be passed on to future generations This is known as an advantage that is selective A particular type of heritable change is phenotypic plasticity which allows individuals to alter their appearance and behaviour in response to environmental or stress 무료에볼루션 can help them survive in a different habitat or make the most of an opportunity For instance they might grow longer fur to shield themselves from the cold or change color to blend in with a certain surface 에볼루션 사이트 however are not necessarily affecting the genotype and therefore cannot be considered to have contributed to evolutionary change Heritable variation is essential for evolution as it allows adapting to changing environments Natural selection can be triggered by heritable variation as it increases the chance that people with traits that are favorable to a particular environment will replace those who arent However in certain instances the rate at which a gene variant can be passed on to the next generation isnt fast enough for natural selection to keep pace Many harmful traits like genetic disease are present in the population despite their negative effects This is due to the phenomenon of reduced penetrance which means that certain individuals carrying the diseaserelated gene variant do not show any signs or symptoms of the condition Other causes are interactions between genes and environments and nongenetic influences such as diet lifestyle and exposure to chemicals In order to understand the reason why some negative traits arent eliminated by natural selection it is necessary to have a better understanding of how genetic variation influences the process of evolution Recent studies have shown genomewide association studies that focus on common variants dont capture the whole picture of disease susceptibility and that rare variants are responsible for the majority of heritability It is imperative to conduct additional studies based on sequencing to identify the rare variations that exist across populations around the world and determine their effects including geneby environment interaction Environmental Changes Natural selection influences evolution the environment impacts species through changing the environment within which they live This principle is illustrated by the infamous story of the peppered mops The whitebodied mops which were abundant in urban areas in which coal smoke had darkened tree barks were easy prey for predators while their darkerbodied mates thrived in these new conditions The reverse is also true that environmental change can alter species capacity to adapt to changes they face Human activities are causing environmental change at a global scale and the effects of these changes are irreversible These changes are affecting global biodiversity and ecosystem function Additionally they are presenting significant health hazards to humanity especially in lowincome countries as a result of polluted water air soil and food For instance the increased usage of coal in developing countries such as India contributes to climate change and raises levels of air pollution which threaten human life expectancy Furthermore human populations are consuming the planets scarce resources at an everincreasing rate This increases the chance that a lot of people will be suffering from nutritional deficiency and lack access to safe drinking water The impacts of humandriven changes to the environment on evolutionary outcomes is complex Microevolutionary responses will likely alter the fitness landscape of an organism These changes may also change the relationship between the phenotype and its environmental context For instance a research by Nomoto et al which involved transplant experiments along an altitudinal gradient revealed that changes in environmental signals such as climate and competition can alter a plants phenotype and shift its directional choice away from its previous optimal fit It is therefore crucial to understand how these changes are shaping contemporary microevolutionary responses and how this data can be used to predict the fate of natural populations in the Anthropocene era This is vital since the environmental changes triggered by humans have direct implications for conservation efforts as well as our health and survival This is why it is vital to continue studying the interaction between humandriven environmental changes and evolutionary processes on an international level The Big Bang There are many theories about the origins and expansion of the Universe However none of them is as wellknown as the Big Bang theory which is now a standard in the science classroom The theory provides explanations for a variety of observed phenomena including the abundance of lightelements the cosmic microwave back ground radiation and the large scale structure of the Universe In its simplest form the Big Bang Theory describes how the universe started 138 billion years ago as an unimaginably hot and dense cauldron of energy that has continued to expand ever since This expansion has created everything that is present today including the Earth and its inhabitants The Big Bang theory is widely supported by a combination of evidence including the fact that the universe appears flat to us as well as the kinetic energy and thermal energy of the particles that comprise it the temperature variations in the cosmic microwave background radiation and the proportions of heavy and light elements found in the Universe Furthermore the Big Bang theory also fits well with the data collected by astronomical observatories and telescopes and by particle accelerators and highenergy states In the early 20th century scientists held a minority view on the Big Bang Fred Hoyle publicly criticized it in 1949 However after World War II observational data began to surface which tipped the scales favor of the Big Bang Arno Pennzias Robert Wilson and others discovered the cosmic background radiation in 1964 This omnidirectional signal is the result of the timedependent expansion of the Universe The discovery of the ionized radioactivity with a spectrum that is consistent with a blackbody which is about 2725 K was a major turningpoint for the Big Bang Theory and tipped it in the direction of the prevailing Steady state model The Big Bang is a major element of the popular TV show The Big Bang Theory In the show Sheldon and Leonard use this theory to explain different phenomena and observations including their experiment on how peanut butter and jelly become squished together