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What is Free Evolution Free evolution is the notion that the natural processes of living organisms can cause them to develop over time This includes the development of new species and change in appearance of existing species This has been proven by many examples of stickleback fish species that can thrive in saltwater or fresh water and walking stick insect types that have a preference for specific host plants These are mostly reversible traits however are not able to be the reason for fundamental changes in body plans Evolution by Natural Selection The development of the myriad of living organisms on Earth is an enigma that has fascinated scientists for many centuries The most wellknown explanation is Charles Darwins natural selection an evolutionary process that occurs when betteradapted individuals survive and reproduce more effectively than those that are less welladapted Over time the population of individuals who are welladapted grows and eventually creates a new species Natural selection is an ongoing process and involves the interaction of 3 factors variation reproduction and inheritance Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity within a species Inheritance refers to the transmission of a persons genetic traits including recessive and dominant genes to their offspring Reproduction is the process of producing fertile viable offspring which includes both sexual and asexual methods All of these factors must be in harmony to allow natural selection to take place If for example a dominant gene allele causes an organism reproduce and last longer than the recessive allele The dominant allele will become more common in a population However if the allele confers an unfavorable survival advantage or reduces fertility it will be eliminated from the population This process is selfreinforcing meaning that an organism that has an adaptive trait will live and reproduce more quickly than one with a maladaptive characteristic The greater an organisms fitness measured by its ability reproduce and survive is the more offspring it produces People with desirable traits like a longer neck in giraffes or bright white colors in male peacocks are more likely to be able to survive and create offspring which means they will become the majority of the population in the future Natural selection only acts on populations not on individual organisms This is an important distinction from the Lamarckian theory of evolution which claims that animals acquire traits through use or disuse If a giraffe stretches its neck to catch prey and the neck grows longer then the offspring will inherit this trait The difference in neck size between generations will increase until the giraffe is unable to reproduce with other giraffes 에볼루션 바카라사이트 by Genetic Drift Genetic drift occurs when alleles of one gene are distributed randomly within a population In the end one will attain fixation become so common that it can no longer be eliminated by natural selection while the other alleles drop to lower frequency In the extreme it can lead to a single allele dominance The other alleles are essentially eliminated and heterozygosity falls to zero In a small group it could lead to the total elimination of recessive alleles This scenario is called the bottleneck effect It is typical of the evolutionary process that occurs when a large number individuals migrate to form a group A phenotypic bottleneck can also happen when the survivors of a disaster such as an epidemic or a mass hunt are confined in a limited area The surviving individuals will be mostly homozygous for the dominant allele meaning that they all share the same phenotype and will consequently share the same fitness characteristics This situation might be caused by conflict earthquake or even a plague Whatever the reason the genetically distinct group that remains could be susceptible to genetic drift Walsh Lewens and Ariew define drift as a departure from the expected values due to differences in fitness They cite a famous example of twins that are genetically identical and have the exact same phenotype and yet one is struck by lightning and dies whereas the other lives and reproduces This type of drift is vital to the evolution of a species Its not the only method of evolution The main alternative is a process known as natural selection in which phenotypic variation in a population is maintained by mutation and migration Stephens argues that there is a big difference between treating drift as a force or an underlying cause and considering other causes of evolution such as mutation selection and migration as forces or causes He argues that a causalprocess explanation of drift lets us distinguish it from other forces and this differentiation is crucial He also claims that drift has a direction that is it tends to eliminate heterozygosity and that it also has a magnitude that is determined by population size Evolution by Lamarckism When students in high school take biology classes they are frequently introduced to the work of JeanBaptiste Lamarck 1744 1829 His theory of evolution also referred to as Lamarckism is based on the idea that simple organisms develop into more complex organisms through taking on traits that are a product of the organisms use and misuse Lamarckism is usually illustrated with an image of a giraffe extending its neck longer to reach the higher branches in the trees This could cause giraffes to pass on their longer necks to offspring which then get taller Lamarck was a French zoologist and in his inaugural lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on 17 May 1802 he presented a groundbreaking concept that radically challenged the previous understanding of organic transformation According Lamarck living organisms evolved from inanimate matter by a series of gradual steps Lamarck was not the first to suggest that this might be the case but the general consensus is that he was the one giving the subject his first comprehensive and thorough treatment The predominant story is that Charles Darwins theory on natural selection and Lamarckism were rivals in the 19th century Darwinism eventually won leading to the development of what biologists refer to as the Modern Synthesis The theory argues that acquired traits are passed down from generation to generation and instead it claims that organisms evolve through the selective influence of environmental factors such as Natural Selection Although Lamarck supported the notion of inheritance through acquired characters and his contemporaries also offered a few words about this idea however it was not a central element in any of their evolutionary theorizing This is partly due to the fact that it was never tested scientifically Its been over 200 years since the birth of Lamarck and in the field of age genomics there is an increasing body of evidence that supports the heritabilityacquired characteristics This is often referred to as neoLamarckism or more commonly epigenetic inheritance This is a variant that is just as valid as the popular neodarwinian model Evolution by Adaptation One of the most common misconceptions about evolution is that it is driven by a sort of struggle for survival This is a false assumption and ignores other forces driving evolution The fight for survival is more accurately described as a struggle to survive in a particular environment This could be a challenge for not just other living things but also the physical environment itself To understand how evolution functions it is important to think about what adaptation is It is a feature that allows a living organism to live in its environment and reproduce It could be a physical structure such as feathers or fur It could also be a behavior trait that allows you to move into the shade during hot weather or escaping the cold at night The ability of a living thing to extract energy from its environment and interact with other organisms as well as their physical environments is crucial to its survival The organism must possess the right genes for producing offspring and be able find sufficient food and resources Furthermore the organism needs to be capable of reproducing itself at a high rate within its niche These factors in conjunction with mutations and gene flow can lead to a shift in the proportion of different alleles in the gene pool of a population This change in allele frequency can result in the emergence of new traits and eventually new species over time Many of the features we find appealing in animals and plants are adaptations For example lung or gills that extract oxygen from air feathers and fur for insulation long legs to run away from predators and camouflage to hide However a thorough understanding of adaptation requires attention to the distinction between behavioral and physiological characteristics Physiological adaptations such as the thick fur or gills are physical characteristics whereas behavioral adaptations such as the tendency to seek out companions or to retreat into the shade in hot weather are not In addition it is important to remember that a lack of thought does not make something an adaptation In fact failure to think about the implications of a decision can render it ineffective despite the fact that it appears to be logical or even necessary