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What is Free Evolution Free evolution is the idea that natural processes can cause organisms to develop over time This includes the emergence and development of new species This is evident in many examples such as the stickleback fish species that can be found in saltwater or fresh water and walking stick insect species that have a preference for specific host plants These mostly reversible trait permutations however are not able to explain fundamental changes in body plans Evolution by Natural Selection The evolution of the myriad living organisms on Earth is an enigma that has intrigued scientists for centuries The most widely accepted explanation is that of Charles Darwins natural selection which occurs when individuals that are better adapted survive and reproduce more effectively than those less well adapted As time passes the number of welladapted individuals grows and eventually develops into a new species Natural selection is an ongoing process that is characterized by the interaction of three elements including inheritance variation and reproduction Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity of an animal species Inheritance refers to the passing of a persons genetic traits to his or her offspring that includes dominant and recessive alleles Reproduction is the process of producing fertile viable offspring which includes both asexual and sexual methods All of these variables must be in balance for natural selection to occur If for instance the dominant gene allele allows an organism to reproduce and live longer than the recessive allele then the dominant allele becomes more prevalent in a group If the allele confers a negative advantage to survival or decreases the fertility of the population it will be eliminated This process is selfreinforcing which means that an organism with an adaptive characteristic will live and reproduce much more than those with a maladaptive feature The more offspring an organism can produce the better its fitness which is measured by its capacity to reproduce and survive People with desirable traits such as longer necks in giraffes or bright white color patterns in male peacocks are more likely to be able to survive and create offspring so they will eventually make up the majority of the population over time Natural selection is only an element in the population and not on individuals This is a significant distinction from the Lamarckian theory of evolution which argues that animals acquire characteristics by use or inactivity For instance if a giraffes neck gets longer through stretching to reach for prey and its offspring will inherit a more long neck The differences in neck length between generations will persist until the giraffes neck becomes too long that it can not breed with other giraffes Evolution by Genetic Drift Genetic drift occurs when alleles from the same gene are randomly distributed within a population At some point only one of them will be fixed become widespread enough to not longer be eliminated by natural selection and the rest of the alleles will diminish in frequency In the extreme this leads to a single allele dominance The other alleles are essentially eliminated and heterozygosity decreases to zero In a small number of people it could lead to the complete elimination of recessive alleles This scenario is called the bottleneck effect and is typical of an evolution process that occurs when a large number individuals migrate to form a group A phenotypic bottleneck can also occur when the survivors of a catastrophe such as an outbreak or a mass hunting event are confined to an area of a limited size The surviving individuals will be largely homozygous for the dominant allele which means they will all have the same phenotype and will therefore share the same fitness characteristics This may be the result of a conflict earthquake or even a cholera outbreak The genetically distinct population if it is left could be susceptible to genetic drift Walsh Lewens and Ariew use a purely outcomeoriented definition of drift as any deviation from the expected values for differences in fitness They give a famous instance of twins who are genetically identical and have identical phenotypes but one is struck by lightning and dies whereas the other lives and reproduces This type of drift is crucial in the evolution of the species But its not the only method to evolve Natural selection is the primary alternative where mutations and migrations maintain the phenotypic diversity in the population Stephens claims that there is a significant difference between treating drift like an agent or cause and treating other causes like migration and selection as forces and causes He claims that a causalprocess model of drift allows us to distinguish it from other forces and this distinction is crucial He further argues that drift is both direction ie it tends towards eliminating heterozygosity It also has a size which is determined based on the size of the population Evolution through Lamarckism When high school students study biology they are often introduced to the work of JeanBaptiste Lamarck 1744 1829 His theory of evolution often referred to as Lamarckism which means that simple organisms develop into more complex organisms through adopting traits that result from the use and abuse of an organism Lamarckism is typically illustrated by an image of a giraffe that extends its neck to reach the higher branches in the trees This would cause the necks of giraffes that are longer to be passed to their offspring who would then become taller Lamarck was a French Zoologist In his lecture to begin his course on invertebrate zoology 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 In his opinion living things had evolved from inanimate matter via an escalating series of steps Lamarck wasnt the first to suggest this however he was widely considered to be the first to provide the subject a comprehensive and general treatment The most popular story is that Lamarckism became a rival to Charles Darwins theory of evolution by natural selection and that the two theories battled out in the 19th century Darwinism eventually prevailed leading to what biologists call the Modern Synthesis The theory denies that acquired characteristics can be passed down through generations and instead argues that organisms evolve through the influence of environment elements like Natural Selection While Lamarck endorsed the idea of inheritance by acquired characters and his contemporaries also paid lipservice to this notion it was never an integral part of any of their evolutionary theories This is due in part to the fact that it was never validated scientifically Its been over 200 year since Lamarcks birth and in the field of age genomics there is a growing evidence base that supports the heritability acquired characteristics This is also referred to as neo Lamarckism or more often epigenetic inheritance This is a version that is just as valid as the popular neodarwinian model Evolution by Adaptation One of the most commonlyheld misconceptions about evolution is being driven by a struggle to survive In fact this view is a misrepresentation of natural selection and ignores the other forces that are driving evolution The fight for survival is better described as a fight to survive in a certain environment This could include not just other organisms but also the physical environment itself Understanding adaptation is important to understand evolution Adaptation is any feature that allows a living thing to survive in its environment and reproduce It can be a physical structure such as feathers or fur Or 에볼루션 바카라 사이트 can be a trait of behavior that allows you to move to the shade during hot weather or coming out to avoid the cold at night The survival of an organism is dependent on its ability to obtain energy from the surrounding environment and interact with other organisms and their physical environments The organism should possess the right genes for producing offspring and be able to find enough food and resources The organism should also be able reproduce at a rate that is optimal for its specific niche These factors in conjunction with mutations and gene flow can cause changes in the proportion of different alleles in the populations gene pool Over time this change in allele frequencies can result in the emergence of new traits and ultimately new species A lot of the traits we admire about animals and plants are adaptations such as lungs or gills to extract oxygen from the air feathers or fur to protect themselves and long legs for running away from predators and camouflage for hiding However a thorough understanding of adaptation requires paying attention to the distinction between behavioral and physiological traits Physiological adaptations like thick fur or gills are physical traits whereas behavioral adaptations such as the tendency to search for companions or to move into the shade in hot weather are not It is also important to note that lack of planning does not cause an adaptation In fact failing to think about the consequences of a behavior can make it unadaptable despite the fact that it might appear reasonable or even essential