What is Free Evolution?
Free evolution is the idea that the natural processes of living organisms can lead to their development over time. This includes the development of new species and the alteration of the appearance of existing ones.
A variety of examples have been provided of this, including different varieties of fish called sticklebacks that can live in either salt or fresh water, and walking stick insect varieties that are attracted to specific host plants. These mostly reversible traits permutations cannot explain fundamental changes to the basic body plan.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is an enigma that has intrigued scientists for decades. Charles Darwin's natural selectivity is the best-established explanation. This happens when people who are more well-adapted survive and reproduce more than those who are less well-adapted. Over time, the population of well-adapted individuals grows and eventually develops into an entirely new species.
Natural selection is an ongoing process that involves the interaction of three factors: variation, inheritance and reproduction. Variation is caused by mutation and sexual reproduction, both of which increase the genetic diversity of an animal species. Inheritance is the passing of a person's genetic traits to their offspring, which includes both dominant and recessive alleles. Reproduction is the process of creating viable, fertile offspring. This can be done via sexual or asexual methods.
Natural selection is only possible when all of these factors are in balance. If, for example, a dominant gene allele makes an organism reproduce and live longer than the recessive gene allele The dominant allele is more common in a population. However, if the gene confers an unfavorable survival advantage 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 much more than those with a maladaptive trait. The higher the level of fitness an organism has which is measured by its ability to reproduce and endure, is the higher number of offspring it produces. People with desirable characteristics, such as the long neck of giraffes, 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 an aspect of populations and not on individuals. This is a significant distinction from the Lamarckian theory of evolution, which argues that animals acquire characteristics through use or disuse. If a giraffe expands its neck to reach prey, and the neck becomes larger, then its offspring will inherit this trait. The difference in neck length between generations will continue until the giraffe's neck gets so long that it can not breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles within a gene can reach different frequencies in a population by chance events. At some point, only one of them will be fixed (become widespread enough to not more be eliminated through natural selection) and the other alleles diminish in frequency. This could lead to a dominant allele at the extreme. The other alleles are eliminated, and heterozygosity is reduced to zero. In a small number of people it could result in the complete elimination the recessive gene. This is called a bottleneck effect, and it is typical of evolutionary process when a large number of individuals migrate to form a new group.
A phenotypic bottleneck may occur when survivors of a disaster like an epidemic or a mass hunt, are confined into a small area. The surviving individuals will be largely homozygous for the dominant allele which means that they will all have the same phenotype and consequently have the same fitness characteristics. This situation could be caused by earthquakes, war or even a plague. Whatever the reason the genetically distinct population that remains is susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from the expected value due to differences in fitness. They give the famous example of twins that are genetically identical and have exactly the same phenotype, but one is struck by lightning and dies, while the other continues to reproduce.
This kind of drift could play a crucial part in the evolution of an organism. It's not the only method for evolution. The primary alternative is a process known as natural selection, in which the phenotypic variation of a population is maintained by mutation and migration.
에볼루션 바카라사이트 argues that there is a major difference between treating drift as a force, or an underlying cause, and treating other causes of evolution such as selection, mutation and migration as forces or causes. Stephens claims that a causal process model of drift allows us to distinguish it from other forces and that this distinction is essential. He argues further that drift has a direction, i.e., it tends towards eliminating heterozygosity. It also has a size, which is determined based on population size.
Evolution by Lamarckism
Students of biology in high school are often introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution, often referred to as "Lamarckism is based on the idea that simple organisms develop into more complex organisms adopting traits that result from the organism's use and misuse. Lamarckism is typically illustrated with the image of a giraffe that extends its neck to reach the higher branches in the trees. This could cause the longer necks of giraffes to be passed to their offspring, who would then grow even taller.
Lamarck the French Zoologist from France, presented a revolutionary concept in his opening lecture at the Museum of Natural History of Paris. He challenged the traditional thinking about organic transformation. In his opinion living things evolved from inanimate matter via a series of gradual steps. Lamarck wasn't the first to make this claim, but he was widely considered to be the first to provide the subject a comprehensive and general explanation.
The predominant story is that Charles Darwin's theory of natural selection and Lamarckism were competing in the 19th Century. Darwinism eventually prevailed and led to the development of what biologists today call the Modern Synthesis. The theory argues that acquired characteristics can be acquired through inheritance and instead argues that organisms evolve through the selective action of environmental factors, including natural selection.
Although Lamarck supported the notion of inheritance by acquired characters, and his contemporaries also paid lip-service to this notion however, it was not a central element in any of their theories about evolution. This is largely due to the fact that it was never tested 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 that supports the heritability of acquired characteristics. This is also known 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 driven by a type of struggle for survival. This view misrepresents natural selection and ignores the other forces that determine the rate of evolution. The fight for survival can be more effectively described as a struggle to survive in a specific environment, which can involve not only other organisms but also the physical environment.
Understanding adaptation is important to understand evolution. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce in its environment. It could be a physiological feature, like feathers or fur or a behavior, such as moving into shade in hot weather or coming out at night to avoid the cold.
The capacity of an organism to draw energy from its surroundings and interact with other organisms, as well as their physical environment is essential to its survival. The organism needs to have the right genes to produce offspring, and must be able to locate sufficient food and other resources. The organism should also be able to reproduce itself at an amount that is appropriate for its particular niche.
These elements, along with mutations and gene flow can result in a shift in the proportion of different alleles in the population's gene pool. Over time, this change in allele frequency can result in the development of new traits and ultimately new species.
A lot of the traits we appreciate in plants and animals are adaptations. For instance lung or gills that extract oxygen from air feathers and fur as insulation long legs to run away from predators, and camouflage to hide. However, a proper understanding of adaptation requires attention to the distinction between behavioral and physiological traits.
Physical characteristics like the thick fur and gills are physical characteristics. Behavior adaptations aren't, such as the tendency of animals to seek companionship or retreat into shade during hot weather. It is also important to remember that a insufficient planning does not result in an adaptation. Inability to think about the consequences of a decision even if it appears to be logical, can make it unadaptive.