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What is Free Evolution?
Free evolution is the concept that the natural processes that organisms go through can cause them to develop over time. This includes the creation of new species as well as the change in appearance of existing ones.
This has been demonstrated by numerous examples such as the stickleback fish species that can thrive in salt or fresh water, and walking stick insect species that are apprehensive about specific host plants. These mostly reversible traits permutations cannot explain fundamental changes to the body's basic plans.
Evolution by Natural Selection
The development of the myriad of living organisms on Earth is an enigma that has intrigued scientists for many centuries. The best-established explanation is Charles Darwin's natural selection process, an evolutionary process that is triggered when more well-adapted individuals live longer and reproduce more effectively than those who are less well adapted. Over time, a community of well adapted individuals grows and eventually forms a whole new species.
Natural selection is an ongoing process and involves the interaction of three factors: variation, reproduction and inheritance. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity within an animal species. Inheritance is the term used to describe the transmission of a person's genetic traits, which include recessive and dominant genes to their offspring. Reproduction is the generation of fertile, viable offspring, which includes both asexual and sexual methods.
All of these variables must be in balance to allow natural selection to take place. For example, if the dominant allele of one gene causes an organism to survive and reproduce more often than the recessive allele the dominant allele will become more prominent within the population. If the allele confers a negative survival advantage or reduces the fertility of the population, it will be eliminated. The process is self reinforcing meaning that an organism with an adaptive characteristic will live and reproduce more quickly than those with a maladaptive feature. The more offspring an organism produces, the greater its fitness, which is measured by its capacity to reproduce itself and live. People with good traits, like having a longer neck in giraffes and bright white patterns of color in male peacocks, are more likely to be able to survive and create offspring, so they will become the majority of the population in the future.
Natural selection is only a force for populations, not on individual organisms. This is a crucial distinction from the Lamarckian theory of evolution, which states that animals acquire traits through usage or inaction. For example, if a giraffe's neck gets longer through stretching to reach prey and its offspring will inherit a larger neck. The differences in neck size between generations will continue to increase until the giraffe becomes unable to reproduce with other giraffes.
Evolution by Genetic Drift
In the process of genetic drift, alleles within a gene can be at different frequencies within a population through random events. Eventually, only one will be fixed (become common enough to no longer be eliminated through natural selection) and the other alleles diminish in frequency. This can lead to an allele that is dominant at the extreme. Other alleles have been basically eliminated and heterozygosity has been reduced to a minimum. In a small number of people, this could result in the complete elimination of the recessive gene. This is known as the bottleneck effect. It is typical of an evolution process that occurs when the number of individuals migrate to form a population.
A phenotypic 'bottleneck' can also occur when survivors of a disaster such as an outbreak or a mass hunting event are confined to an area of a limited size. The surviving individuals will be mostly homozygous for the dominant allele, meaning that they all have the same phenotype and consequently have the same fitness traits. This may be the result of a conflict, earthquake, or even a plague. The genetically distinct population, if left susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew use Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from the expected values for variations in fitness. They provide a well-known example of twins that are genetically identical and have the exact same phenotype but one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift can play a crucial part in the evolution of an organism. It is not the only method for evolution. Natural selection is the primary alternative, in which mutations and migration keep phenotypic diversity within a population.
Stephens argues there is a vast distinction between treating drift as a force or cause, and treating other causes such as selection mutation and migration as causes and forces. He claims that a causal-process explanation of drift lets us distinguish it from other forces, and this distinction is crucial. He also claims that drift has a direction: that is it tends to reduce heterozygosity. It also has a magnitude, which is determined by the size of population.
Evolution through Lamarckism
When high school students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is generally referred to as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms via the inheritance of characteristics that result from an organism's natural activities use and misuse. Lamarckism is illustrated through the giraffe's neck being extended to reach higher leaves in the trees. This process would cause giraffes to give their longer necks to their offspring, which then get taller.
Lamarck, a French zoologist, presented a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged the previous thinking on organic transformation. In his opinion living things had evolved from inanimate matter through a series of gradual steps. Lamarck was not the first to propose this, but he was widely regarded as the first to give the subject a thorough and general explanation.
The prevailing story is that Lamarckism became a rival to Charles Darwin's theory of evolutionary natural selection, and both theories battled each other in the 19th century. Darwinism ultimately prevailed which led to what biologists call the Modern Synthesis. This theory denies that acquired characteristics can be acquired through inheritance and instead, it argues that organisms develop through the selective action of environmental factors, such as natural selection.
Lamarck and his contemporaries endorsed the idea that acquired characters could be passed down to future generations. However, this concept was never a central part of any of their evolutionary theories. This is partly because it was never tested scientifically.
It's been over 200 year since Lamarck's birth and in the field of genomics, there is a growing body of evidence that supports the heritability acquired characteristics. This is also referred to as "neo Lamarckism", or more often epigenetic inheritance. It is a form of evolution that is just as valid as the more popular neo-Darwinian model.
Evolution by Adaptation
One of the most widespread misconceptions about evolution is that it is a result of a kind of struggle to survive. 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 specific environment. This could include not just other organisms but also the physical environment itself.
Understanding the concept of adaptation is crucial to understand evolution. It refers to a specific feature that allows an organism to survive and reproduce within its environment. 에볼루션 바카라 체험 can be a physical structure such as feathers or fur. Or it can be a behavior trait, like moving towards shade during the heat, or moving out to avoid the cold at night.
The survival of an organism is dependent on its ability to obtain energy from the environment and interact with other living organisms and their physical surroundings. The organism should possess the right genes to create offspring and to be able to access enough food and resources. In addition, the organism should be able to reproduce itself at a high rate within its environment.
These factors, together with gene flow and mutations can cause changes in the proportion of different alleles within the population's gene pool. Over time, this change in allele frequencies could result in the emergence of new traits, and eventually new species.
A lot of the traits we admire in animals and plants are adaptations. For instance, lungs or gills that extract oxygen from the air, fur and feathers as insulation long legs to run away from predators and camouflage for hiding. To comprehend adaptation it is crucial to distinguish between behavioral and physiological traits.
Physiological adaptations like 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, aren't. It is important to note that the absence of planning doesn't result in an adaptation. Failure to consider the effects of a behavior even if it seems to be logical, can make it unadaptive.