What is Free Evolution?
Free evolution is the notion that the natural processes that organisms go through can cause them to develop over time. This includes the development of new species and change in appearance of existing species.
This has been demonstrated by many examples, including stickleback fish varieties that can be found in fresh or saltwater and walking stick insect types that prefer particular host plants. These are mostly reversible traits, however, cannot explain fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all living creatures that live on our planet for many centuries. The best-established explanation is Charles Darwin's natural selection process, a process that occurs when individuals that are better adapted survive and reproduce more successfully than those that are less well-adapted. As time passes, the number of individuals who are well-adapted grows and eventually forms an entirely new species.
Natural selection is an ongoing process that involves the interaction of three factors: variation, inheritance and reproduction. Sexual reproduction and mutations increase genetic diversity in a species. Inheritance refers the transmission of a person’s genetic characteristics, which includes both dominant and recessive genes to their offspring. Reproduction is the process of producing fertile, viable offspring. This can be done by both asexual or sexual methods.
All of these factors have to be in equilibrium for natural selection to occur. If, for example an allele of a dominant gene causes an organism reproduce and survive more than the recessive allele then the dominant allele will become more prevalent in a group. However, if the allele confers a disadvantage in survival or reduces fertility, it will disappear from the population. The process is self-reinforcing, which means that an organism that has a beneficial trait will survive and reproduce more than one with an inadaptive characteristic. The more offspring an organism produces the better its fitness which is measured by its capacity to reproduce and survive. Individuals with favorable traits, like a long neck in the giraffe, or bright white patterns on male peacocks, are more likely than others to survive and reproduce, which will eventually lead to them becoming the majority.
Natural selection is only a force for populations, not on individual organisms. This is a major distinction from the Lamarckian theory of evolution, which argues that animals acquire characteristics through use or disuse. For example, if a animal's neck is lengthened by reaching out to catch prey and its offspring will inherit a larger neck. The length difference between generations will persist until the giraffe's neck gets too long that it can not breed with other giraffes.
Evolution by Genetic Drift
In the process of genetic drift, alleles within a gene can attain different frequencies in a group by chance events. Eventually, one of them will attain fixation (become so widespread that it is unable to be eliminated through natural selection), while other alleles fall to lower frequencies. This could lead to dominance in the extreme. The other alleles have been essentially eliminated and heterozygosity has been reduced to a minimum. In a small group this could lead to the complete elimination of the recessive gene. This is known as a bottleneck effect and it is typical of evolutionary process that takes place when a large number of people migrate to form a new population.
A phenotypic 'bottleneck' can also occur when the survivors of a catastrophe such as an outbreak or mass hunt event are confined to the same area. The surviving individuals will be mostly homozygous for the dominant allele, which means they will all have the same phenotype, and consequently have the same fitness traits. This could be caused by earthquakes, war, or even plagues. Regardless of the cause, the genetically distinct population that remains could be susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from the expected values due to differences in fitness. They give a famous example of twins that are genetically identical, have the exact same phenotype but one is struck by lightening and dies while the other lives and reproduces.
This kind of drift could play a significant part in the evolution of an organism. However, it's not the only way to develop. The main alternative is a process called natural selection, in which the phenotypic variation of an individual is maintained through mutation and migration.
Stephens claims that there is a significant difference between treating the phenomenon of drift as a force or cause, and treating other causes like migration and selection as causes and forces. Stephens claims that a causal process account of drift allows us to distinguish it from other forces, and that this distinction is crucial. He further argues that drift has a direction, i.e., it tends to reduce heterozygosity. It also has a size, which is determined by population size.
Evolution by Lamarckism
In high school, students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, commonly referred to as “Lamarckism”, states that simple organisms evolve into more complex organisms by adopting traits that result from the use and abuse of an organism. Lamarckism is illustrated through an giraffe's neck stretching to reach higher leaves in the trees. This would cause giraffes to give their longer necks to offspring, who would then become taller.
Lamarck was a French zoologist and, in his inaugural lecture for his course on invertebrate zoology at the Museum of Natural History in Paris on the 17th May 1802, he introduced an innovative concept that completely challenged the previous understanding of organic transformation. According to Lamarck, living creatures evolved from inanimate materials through a series gradual steps. Lamarck was not the only one to suggest that this might be the case but the general consensus is that he was the one giving the subject his first comprehensive and comprehensive treatment.
The dominant story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were rivals in the 19th century. Darwinism eventually prevailed, leading to what biologists refer to as the Modern Synthesis. The theory argues the possibility that acquired traits can be inherited, and instead suggests that organisms evolve 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, 에볼루션바카라사이트 was never a central part of any of their theories about evolution. This is due to the fact that it was never tested scientifically.
But it is now more than 200 years since Lamarck was born and in the age genomics there is a vast amount of evidence to support the heritability of acquired characteristics. This is also referred to as "neo Lamarckism", or more generally epigenetic inheritance. It is a form of evolution that is as relevant as the more popular Neo-Darwinian model.
Evolution by Adaptation
One of the most popular misconceptions about evolution is that it is a result of a kind of struggle for survival. In reality, this notion misrepresents natural selection and ignores the other forces that determine the rate of evolution. The struggle for survival is more precisely described as a fight to survive within a specific environment, which could involve not only other organisms, but also the physical environment.
To understand how evolution operates, it is helpful to think about what adaptation is. Adaptation is any feature that allows a living organism to survive in its environment and reproduce. It could be a physiological feature, like feathers or fur or a behavior such as a tendency to move into the shade in hot weather or stepping out at night to avoid cold.
The survival of an organism is dependent on its ability to draw energy from the surrounding environment and interact with other living organisms and their physical surroundings. The organism must possess the right genes to produce offspring, and it must be able to find sufficient food and other resources. Moreover, the organism must be capable of reproducing at an optimal rate within its environmental niche.
These factors, in conjunction with gene flow and mutations can result in changes in the proportion of different alleles within the gene pool of a population. As time passes, this shift in allele frequencies could result in the development of new traits and ultimately new species.
Many of the characteristics we admire in animals and plants are adaptations, for example, lungs or gills to extract oxygen from the air, fur or feathers for insulation, long legs for running away from predators, and camouflage for hiding. However, a proper understanding of adaptation requires attention to the distinction between behavioral and physiological characteristics.
Physiological traits like large gills and thick fur are physical characteristics. Behavioral adaptations are not like the tendency of animals to seek companionship or retreat into shade during hot weather. It is also important to keep in mind that insufficient planning does not make an adaptation. Inability to think about the effects of a behavior even if it appears to be rational, may make it inflexible.