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What is Free Evolution Free evolution is the notion that natural processes can cause organisms to develop over time This includes the evolution of new species and alteration of the appearance of existing species This is evident in many examples of stickleback fish species that can live in saltwater or fresh water and walking stick insect species that prefer specific host plants These reversible traits are not able to explain fundamental changes to the basic body plan Evolution through Natural Selection Scientists have been fascinated by the evolution of all the living creatures that inhabit our planet for ages Charles Darwins natural selection theory is the most wellknown explanation This happens when individuals who are betteradapted have more success in reproduction and survival than those who are less welladapted As time passes a group of welladapted individuals expands and eventually becomes a new species Natural selection is a process that is cyclical and involves the interaction of three factors including reproduction variation and inheritance Variation is caused by mutation and sexual reproduction both of which increase the genetic diversity within an animal species Inheritance is the transfer of a persons genetic traits to his or her offspring which includes both recessive and dominant alleles Reproduction is the generation of fertile viable offspring which includes both asexual and sexual methods Natural selection only occurs when all these elements are in equilibrium If for example a dominant gene allele causes an organism reproduce and live longer than the recessive gene allele then the dominant allele is more prevalent in a group If the allele confers a negative survival advantage or lowers the fertility of the population it will disappear The process is selfreinforcing which means that an organism with a beneficial characteristic will survive and reproduce more than an individual with an inadaptive characteristic The greater an organisms fitness which is measured by its ability to reproduce and survive is the greater number of offspring it will produce People with desirable characteristics such as a long neck in Giraffes or the bright white patterns on male peacocks are more likely than others to live and reproduce which will eventually lead to them becoming the majority Natural selection is an aspect of populations and not on individuals This is a major distinction from the Lamarckian theory of evolution which states that animals acquire traits through use or neglect If a giraffe stretches its neck to reach prey and the neck grows longer then the offspring will inherit this characteristic The length difference between generations will continue until the giraffes neck becomes too long to no longer breed with other giraffes Evolution by Genetic Drift In genetic drift the alleles at a gene may be at different frequencies within a population due to random events In the end only one will be fixed become common enough that it can no longer be eliminated by natural selection and the other alleles will decrease in frequency This could lead to a dominant allele in the extreme The other alleles are eliminated and heterozygosity falls to zero In a small group it could result in the complete elimination of the recessive gene This scenario is called the bottleneck effect and is typical of an evolutionary process that occurs whenever a large number individuals migrate to form a group A phenotypic bottleneck could happen when the survivors of a catastrophe such as an epidemic or a mass hunting event are concentrated into a small area The remaining individuals will be mostly homozygous for the dominant allele which means they will all have the same phenotype and will thus have the same fitness characteristics This could be caused by war an earthquake or even a disease Whatever the reason the genetically distinct group that remains could be susceptible to genetic drift Walsh Lewens and Ariew employ Lewens Walsh and Ariew employ a purely outcomeoriented definition of drift as any deviation from expected values for variations in fitness They provide the famous case of twins who are genetically identical and have exactly the same phenotype but one is struck by lightning and dies while the other lives to reproduce This kind of drift could play a significant role in the evolution of an organism However 에볼루션 카지노 is not the only method to progress Natural selection is the primary alternative in which mutations and migration keep phenotypic diversity within a population Stephens claims that there is a significant difference between treating the phenomenon of drift as an agent or cause and considering other causes such as migration and selection mutation as forces and causes Stephens claims that a causal mechanism account of drift permits us to differentiate it from these other forces and this distinction is vital He also argues that drift has an orientation ie it tends to eliminate heterozygosity It also has a size which is determined by the size of the population Evolution through Lamarckism Biology students in high school are frequently introduced to JeanBaptiste Lamarcks 17441829 work His theory of evolution also referred to as Lamarckism states that simple organisms transform into more complex organisms through inheriting characteristics that result from the use and abuse of an organism Lamarckism can be illustrated by an giraffes neck stretching to reach higher levels of leaves in the trees This would result in giraffes passing on their longer necks to their offspring which then get taller Lamarck was a French Zoologist In his inaugural lecture for his course on invertebrate zoology at the Museum of Natural History in Paris on the 17th of May in 1802 he presented a groundbreaking concept that radically challenged previous thinking about organic transformation According to him living things evolved from inanimate matter via a series of gradual steps Lamarck wasnt the first to propose this but he was thought of as the first to give the subject a thorough and general treatment The most popular story is that Lamarckism was an opponent to Charles Darwins theory of evolutionary natural selection and that the two theories fought out in the 19th century Darwinism eventually triumphed and led to the development of what biologists today call the Modern Synthesis The theory argues the possibility that acquired traits can be inherited and instead it argues that organisms develop by the symbiosis of environmental factors such as natural selection Lamarck and his contemporaries supported the notion that acquired characters could be passed down to future generations However this idea was never a central part of any of their theories on evolution This is partly because it was never scientifically tested Its been more than 200 years since the birth of Lamarck and in the age genomics there is a growing evidencebased body of evidence to support the heritability acquired characteristics It is sometimes referred to as neoLamarckism or more frequently epigenetic inheritance This is a variant that is just as valid as the popular Neodarwinian model Evolution through adaptation One of the most widespread misconceptions about evolution is that it is a result of a kind of struggle to survive In reality this notion is a misrepresentation of natural selection and ignores the other forces that are driving evolution The struggle for existence is more accurately described as a struggle to survive in a certain environment This can be a challenge for not just other living things as well as the physical environment itself To understand how evolution operates it is beneficial to understand what is adaptation The term adaptation refers to any characteristic that allows a living thing to survive in its environment and reproduce It can be a physical structure like fur or feathers It could also be a behavior trait that allows you to move to the shade during the heat or coming out to avoid the cold at night An organisms survival depends on its ability to draw energy from the environment and to interact with other living organisms and their physical surroundings The organism must possess the right genes to create offspring and be able to find enough food and resources Furthermore the organism needs to be capable of reproducing at a high rate within its environment These factors together with gene flow and mutations can lead to changes in the proportion of different alleles within the populations gene pool This shift in the frequency of alleles could lead to the development of new traits and eventually new species over time A lot of the traits we admire in animals and plants are adaptations For example the lungs or gills which extract oxygen from the air fur and feathers as insulation and long legs to get away from predators and camouflage to conceal To comprehend adaptation it is crucial to distinguish between behavioral and physiological traits Physiological traits like the thick fur and gills are physical traits The behavioral adaptations arent such as the tendency of animals to seek out companionship or to retreat into the shade during hot weather It is also important to remember that a the absence of planning doesnt make an adaptation In fact a failure to consider the consequences of a decision can render it unadaptable despite the fact that it might appear logical or even necessary