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What is Free Evolution Free evolution is the concept that the natural processes of organisms can lead them to evolve over time This includes the development of new species as well as the transformation of the appearance of existing ones Many examples have been given of this including various varieties of fish called sticklebacks that can live in either salt or fresh water and walking stick insect varieties that prefer particular host plants These typically reversible traits do not explain the fundamental changes in the basic body plan Evolution through Natural Selection Scientists have been fascinated by the evolution of all living creatures that live on our planet for ages The most wellknown explanation is that of Charles Darwins natural selection process an evolutionary process that is triggered when more welladapted individuals live longer and reproduce more effectively than those who are less welladapted Over time the population of individuals who are welladapted grows and eventually forms an entirely new species Natural selection is an ongoing process that involves the interaction of three factors variation inheritance and reproduction Sexual reproduction and mutations increase the genetic diversity of an animal species Inheritance is the term used to describe the transmission of a persons genetic traits which include both dominant and recessive genes to their offspring Reproduction is the process of producing viable fertile offspring This can be done through sexual or asexual methods All of these variables must be in harmony to allow natural selection to take place If for example the dominant gene allele makes an organism reproduce and last longer than the recessive allele The dominant allele becomes more common in a population If the allele confers a negative survival advantage or lowers the fertility of the population it will be eliminated 에볼루션사이트 is selfreinforcing meaning that an organism with a beneficial characteristic is more likely to survive and reproduce than one with a maladaptive characteristic The more fit an organism is which is measured by its ability to reproduce and survive is the more offspring it will produce People with good characteristics like a longer neck in giraffes and bright white patterns of color in male peacocks are more likely survive and have offspring which means they will eventually make up the majority of the population in the future Natural selection only acts on populations not individuals This is an important distinction from the Lamarckian theory of evolution which argues that animals acquire traits through use or neglect For example if a giraffes neck gets longer through stretching to reach prey and its offspring will inherit a more long neck The difference in neck length between generations will persist until the giraffes neck becomes too long that it can not breed with other giraffes Evolution through Genetic Drift Genetic drift occurs when alleles of a gene are randomly distributed in a population In the end only one will be fixed become common enough that it can no more be eliminated through natural selection and the other alleles will drop in frequency This can result in an allele that is dominant at the extreme The other alleles have been essentially eliminated and heterozygosity has been reduced to a minimum In a small group this could result in the total elimination of recessive alleles This scenario is called the bottleneck effect It is typical of the evolutionary process that occurs whenever the number of individuals migrate to form a group A phenotypic bottleneck can also occur when survivors of a disaster such as an epidemic or mass hunting event are concentrated in a limited area The survivors will have an dominant allele and will share the same phenotype This situation might be the result of a war earthquake or even a cholera outbreak The genetically distinct population if it is left susceptible to genetic drift Walsh Lewens and Ariew use Lewens Walsh and Ariew use a purely outcomeoriented definition of drift as any deviation from the expected values for different fitness levels They cite the famous example of twins who are genetically identical and share the same phenotype However one is struck by lightning and dies but the other lives to reproduce This type of drift is crucial in the evolution of the species Its not the only method for evolution Natural selection is the most common alternative where mutations and migration maintain the phenotypic diversity in a population Stephens asserts that there is a big distinction between treating drift as a force or a cause and considering other causes of evolution such as selection mutation and migration as causes or causes He argues that a causalprocess model of drift allows us to distinguish it from other forces and this differentiation is crucial He also argues that drift is a directional force that is it tends to eliminate heterozygosity It also has a magnitude that is determined by the size of population Evolution through Lamarckism When students in high school study biology they are often introduced to the work of JeanBaptiste Lamarck 1744 1829 His theory of evolution is commonly known as Lamarckism and it states that simple organisms grow into more complex organisms through the inherited characteristics that are a result of the natural activities of an organism use and misuse Lamarckism is typically illustrated with an image of a giraffe that extends its neck to reach higher up in the trees This causes the longer necks of giraffes to be passed on to their offspring who would grow taller Lamarck a French zoologist presented a revolutionary concept in his opening lecture at the Museum of Natural History of Paris He challenged the previous thinking on organic transformation According to him living things had evolved from inanimate matter via an escalating series of steps Lamarck wasnt the only one to propose this however he was widely thought of as the first to offer the subject a comprehensive and general treatment The dominant story is that Charles Darwins theory on natural selection and Lamarckism were competing during the 19th century Darwinism eventually prevailed leading to what biologists refer to as the Modern Synthesis This theory denies that traits acquired through evolution can be acquired through inheritance and instead argues that organisms evolve through the selective action of environmental factors like natural selection While Lamarck supported the notion of inheritance by acquired characters and his contemporaries also offered a few words about this idea however it was not an integral part of any of their theories about evolution This is largely due to the fact that it was never validated scientifically Its been more than 200 years since the birth of Lamarck and in the age genomics there is a growing body of evidence that supports the heritability of acquired traits It is sometimes called neoLamarckism or more frequently epigenetic inheritance This is a version that is as reliable as the popular Neodarwinian model Evolution by Adaptation One of the most popular misconceptions about evolution is its being driven by a struggle to survive This view is a misrepresentation of natural selection and ignores the other forces that drive evolution The fight for survival can be more precisely described as a fight to survive in a specific environment which may involve not only other organisms but also the physical environment To understand how evolution operates it is beneficial to think about what adaptation is It is a feature that allows living organisms to live in its environment and reproduce It could be a physical feature like feathers or fur Or it can be a trait of behavior that allows you to move towards shade during hot weather or coming out to avoid the cold at night The capacity of a living thing to extract energy from its environment and interact with other organisms as well as their physical environments is essential to its survival The organism needs to have the right genes to produce offspring and must be able to find sufficient food and other resources The organism should also be able reproduce itself at an amount that is appropriate for its niche These elements along with mutations and gene flow can cause a shift in the proportion of different alleles within the gene pool of a population This change in allele frequency can result in the emergence of novel traits and eventually new species in the course of time Many of the features we appreciate in animals and plants are adaptations For example lungs or gills that extract oxygen from the air feathers and fur as insulation long legs to run away from predators and camouflage to conceal However a thorough understanding of adaptation requires paying attention to the distinction between the physiological and behavioral traits Physical characteristics like the thick fur and gills are physical characteristics Behavior adaptations arent like the tendency of animals to seek companionship or move into the shade in hot temperatures It is important to remember that a insufficient planning does not make an adaptation Failure to consider the implications of a choice even if it appears to be logical can make it inflexible
