What is Free Evolution?
Free evolution is the notion that the natural processes of organisms can lead them to evolve over time. This includes the appearance and growth of new species.
Many examples have been given of this, such as different varieties of fish called sticklebacks that can be found in salt or fresh water, as well as walking stick insect varieties that prefer particular host plants. These reversible traits, however, cannot be the reason for fundamental changes in body plans.
Evolution through Natural Selection
The development of the myriad of living organisms on Earth is a mystery that has fascinated scientists for centuries. 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. As time passes, the number of individuals who are well-adapted grows and eventually creates an entirely new species.
Natural selection is an ongoing process and involves the interaction of 3 factors including reproduction, variation and inheritance. Mutation and sexual reproduction increase genetic diversity in a 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 process of creating viable, fertile offspring. This can be accomplished via sexual or asexual methods.
Natural selection only occurs when all of these factors are in equilibrium. If, for example, a dominant gene allele makes an organism reproduce and survive more than the recessive allele then the dominant allele is more common in a population. If the allele confers a negative advantage to survival or decreases the fertility of the population, it will disappear. This process is self-reinforcing meaning that a species that has a beneficial trait can reproduce and survive longer than an individual with an inadaptive trait. The higher the level of fitness an organism has, measured by its ability reproduce and survive, is the more offspring it will produce. Individuals with favorable characteristics, such as a long neck in giraffes, or bright white patterns on male peacocks are more likely to others to reproduce and survive which eventually leads to them becoming the majority.
Natural selection is only an element in the population and not on individuals. This is a crucial distinction from the Lamarckian evolution theory that states that animals acquire traits due to the use or absence of use. For example, if a animal's neck is lengthened by reaching out to catch prey, its offspring will inherit a larger neck. The difference in neck length between generations will persist until the giraffe's neck becomes too long that it can not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles from the same gene are randomly distributed in a population. At some point, one will attain fixation (become so common that it can no longer be eliminated by natural selection) and other alleles fall to lower frequency. This could lead to dominance at the extreme. The other alleles are eliminated, and heterozygosity is reduced to zero. In a small number of people, this could result in the complete elimination the recessive gene. This is known as the bottleneck effect and is typical of the evolutionary process that occurs when a large number individuals migrate to form a population.
A phenotypic 'bottleneck' can also occur when the survivors of a catastrophe such as an outbreak or a mass hunting event are confined to a small area. The survivors will share an dominant allele, and will share the same phenotype. This may be caused by war, earthquake or even a disease. Whatever the reason the genetically distinct group that is left might be susceptible to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected values due to differences in fitness. They cite the famous example of twins that are genetically identical and have exactly the same phenotype. However, one is struck by lightning and dies, whereas the other is able to reproduce.
This kind of drift can be very important in the evolution of a species. It is not the only method of evolution. Natural selection is the most common alternative, where mutations and migrations maintain phenotypic diversity within a population.
Stephens claims that there is a significant difference between treating drift as a force or an underlying cause, and treating other causes of evolution like mutation, selection, and migration as forces or causes. Stephens claims that a causal mechanism account of drift permits us to differentiate it from other forces, and that this distinction is vital. He further argues that drift is both an orientation, i.e., it tends towards eliminating heterozygosity. It also has a size, that is determined by population size.
Evolution through Lamarckism
Biology students in high school are frequently introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution is often called "Lamarckism" and it states that simple organisms grow into more complex organisms via the inherited characteristics that are a result of the natural activities of an organism usage, use and disuse. Lamarckism can be illustrated by a giraffe extending its neck to reach higher leaves in the trees. This would cause giraffes to give their longer necks to their offspring, who would then become 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 view, living things had evolved from inanimate matter via the gradual progression of events. Lamarck was not the first to make this claim but he was thought of as the first to provide the subject a thorough and general overview.
The popular narrative is that Lamarckism was a rival to Charles Darwin's theory of evolution by natural selection and that the two theories fought it out in the 19th century. Darwinism eventually triumphed, leading to the development of what biologists call the Modern Synthesis. The theory argues the possibility that acquired traits can be acquired through inheritance and instead suggests that organisms evolve by the symbiosis of environmental factors, such as natural selection.
Lamarck and his contemporaries endorsed the idea that acquired characters could be passed on to the next generation. However, this idea was never a key element of any of their evolutionary theories. This is largely 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 of genomics there is a vast body of evidence supporting the heritability of acquired characteristics. It is sometimes referred to as "neo-Lamarckism" or more commonly epigenetic inheritance. It is a version of evolution that is as valid as the more well-known Neo-Darwinian model.
Evolution by the process of adaptation
One of the most popular misconceptions about evolution is its being driven by a struggle for survival. In fact, this view is inaccurate and overlooks the other forces that determine the rate of evolution. The fight for survival can be better described as a struggle to survive in a certain environment. This could include not only other organisms, but also the physical surroundings themselves.
Understanding how adaptation works is essential to comprehend evolution. The term "adaptation" refers to any specific characteristic that allows an organism to live and reproduce within its environment. 에볼루션 룰렛 can be a physiological structure such as fur or feathers or a behavioral characteristic like moving to the shade during hot weather or stepping out at night to avoid cold.
The survival of an organism depends on its ability to extract energy from the environment and to interact with other organisms and their physical environments. The organism must possess the right genes for producing offspring and be able find sufficient food and resources. In addition, the organism should be capable of reproducing in a way that is optimally within its niche.
These elements, in conjunction with mutation and gene flow can result in an alteration in the percentage of alleles (different varieties of a particular gene) in a population's gene pool. As time passes, this shift in allele frequencies could lead to the emergence of new traits, and eventually new species.
Many of the characteristics we appreciate in plants and animals are adaptations. For instance the lungs or gills which draw oxygen from air feathers and fur as insulation long legs to run away from predators and camouflage for hiding. However, a complete understanding of adaptation requires paying attention to the distinction between behavioral and physiological traits.
Physical characteristics like thick fur and gills are physical traits. The behavioral adaptations aren't an exception, for instance, the tendency of animals to seek companionship or move into the shade in hot weather. It is important to remember that a the absence of planning doesn't result in an adaptation. In fact, failure to think about the implications of a behavior can make it unadaptable even though it might appear sensible or even necessary.