What is Free Evolution?
Free evolution is the idea that natural processes can lead to the development of organisms over time. This includes the development of new species and change in appearance of existing ones.
This is evident in many examples such as the stickleback fish species that can live in saltwater or fresh water and walking stick insect varieties that have a preference for particular host plants. These reversible traits, however, cannot explain fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the evolution of all the living creatures that inhabit our planet for ages. The most widely accepted explanation is that of Charles Darwin's natural selection process, a process that occurs when better-adapted individuals survive and reproduce more effectively than those less well adapted. As time passes, a group of well-adapted individuals increases and eventually forms a whole new species.
Natural selection is an ongoing process and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Sexual reproduction and mutation increase the genetic diversity of a species. Inheritance refers to the passing of a person's genetic traits to their offspring which includes both recessive and dominant alleles. Reproduction is the process of producing fertile, viable offspring. This can be achieved via sexual or asexual methods.
All of these elements have to be in equilibrium for natural selection to occur. If, for instance, a dominant gene allele allows an organism to reproduce and last longer than the recessive gene, then the dominant allele is more common in a population. However, if the gene confers a disadvantage in survival or reduces fertility, it will be eliminated from the population. The process is self-reinforcing, which means that an organism that has an adaptive trait will live and reproduce more quickly than one with a maladaptive characteristic. The greater an organism's fitness which is measured by its ability to reproduce and survive, is the more offspring it will produce. People with good traits, like a long neck in the giraffe, or bright white color patterns on male peacocks are more likely to others to survive and reproduce, which will eventually lead to them becoming the majority.
Natural selection is only a force for populations, not individual organisms. This is a significant distinction from the Lamarckian theory of evolution, which argues that animals acquire characteristics through use or neglect. For instance, if a giraffe's neck gets longer through stretching to reach prey and its offspring will inherit a more long neck. The difference in neck size between generations will continue to increase until the giraffe is unable to reproduce with other giraffes.
에볼루션 무료체험 by Genetic Drift
Genetic drift occurs when alleles of one gene are distributed randomly within 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 dominance at the extreme. The other alleles are virtually eliminated and heterozygosity been reduced to zero. In a small group it could lead to the total elimination of recessive alleles. This scenario is called a bottleneck effect, and it is typical of the kind of evolutionary process that occurs when a lot of people migrate to form a new group.
A phenotypic bottleneck can also occur when the survivors of a disaster like an outbreak or mass hunt event are concentrated in an area of a limited size. The survivors will share an allele that is dominant and will share the same phenotype. This could be caused by war, earthquake, or even a plague. The genetically distinct population, if it is left susceptible to genetic drift.
Walsh Lewens and Ariew utilize a "purely outcome-oriented" definition of drift as any deviation from the expected values for variations in fitness. They provide the famous case of twins who are both genetically identical and have exactly the same phenotype. However, one is struck by lightning and dies, but the other lives to reproduce.
This type of drift is vital to the evolution of a species. This isn't the only method of evolution. 에볼루션 무료체험 is to use a process known as natural selection, where phenotypic variation in a population is maintained by mutation and migration.
Stephens asserts that there is a significant difference between treating drift like an actual cause or force, and considering other causes, such as migration and selection as causes and forces. Stephens claims that a causal process explanation of drift permits us to differentiate it from these other forces, and that this distinction is crucial. He also argues that drift has both direction, i.e., it tends to reduce heterozygosity. It also has a size, which is determined based on the size of the population.
Evolution by Lamarckism
In high school, students study biology, they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). 에볼루션 of evolution is generally known as "Lamarckism" and it states that simple organisms grow into more complex organisms through the inherited characteristics which result from an organism's natural activities, use and disuse. Lamarckism is usually illustrated with an image of a giraffe that extends its neck longer to reach leaves higher up in the trees. This could cause giraffes' longer necks to be passed on to their offspring who would then grow even taller.
Lamarck Lamarck, a French Zoologist from France, presented a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged the traditional thinking about organic transformation. According to Lamarck, living things evolved from inanimate matter through a series of gradual steps. Lamarck was not the first to propose this but he was regarded as the first to offer the subject a comprehensive and general treatment.
The dominant story is that Charles Darwin's theory of natural selection and Lamarckism were competing in the 19th century. Darwinism ultimately prevailed which led to what biologists call the Modern Synthesis. The Modern Synthesis theory denies the possibility that acquired traits can be inherited and instead argues that organisms evolve through the action of environmental factors, including natural selection.
Although Lamarck believed in the concept of inheritance by acquired characters, and his contemporaries also offered a few words about this idea, it was never an integral part of any of their evolutionary theorizing. This is due in part to the fact that it was never validated scientifically.
It's been more than 200 years since Lamarck was born and, in the age of genomics, there is a large amount of evidence to support the possibility of inheritance of acquired traits. This is often referred to as "neo-Lamarckism" or more commonly epigenetic inheritance. This is a variant that is as valid as the popular neodarwinian model.
Evolution by adaptation
One of the most common misconceptions about evolution is being driven by a struggle for survival. This is a false assumption and overlooks other forces that drive evolution. The fight for survival can be better described as a struggle to survive in a specific environment. This could be a challenge for not just other living things but also the physical surroundings themselves.
Understanding the concept of adaptation is crucial to understand evolution. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce in its environment. It could be a physical structure, like fur or feathers. It could also be a behavior trait, like moving into the shade during hot weather or escaping the cold at night.
The survival of an organism depends on its ability to extract energy from the surrounding environment and interact with other organisms and their physical environments. The organism must possess the right genes to produce offspring, and must be able to locate sufficient food and other resources. In addition, the organism should be able to reproduce itself at a high rate within its environment.
These factors, in conjunction with gene flow and mutations can cause a shift in the proportion of different alleles in a population’s gene pool. This change in allele frequency can lead to the emergence of new traits and eventually new species as time passes.
A lot of the traits we admire in plants and animals are adaptations. For instance lung or gills that extract oxygen from air, fur and feathers 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 behavioral and physiological characteristics.
Physical characteristics like the thick fur and gills are physical characteristics. Behavioral adaptations are not, such as the tendency of animals to seek out companionship or move into the shade during hot temperatures. Additionally it is important to remember that a lack of thought does not mean that something is an adaptation. In fact, failing to think about the implications of a behavior can make it unadaptive despite the fact that it may appear to be sensible or even necessary.