What is Free Evolution?
Free evolution is the notion that natural processes can lead to the development of organisms over time. This includes the evolution of new species and change in appearance of existing ones.
This is evident in numerous examples, including stickleback fish varieties that can live in saltwater or fresh water and walking stick insect varieties that prefer particular host plants. These mostly reversible traits permutations do not explain the fundamental changes in the basic body plan.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is a mystery that has fascinated scientists for many centuries. The best-established explanation is that of Charles Darwin's natural selection process, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more effectively than those that are less well-adapted. Over time, the population of well-adapted individuals grows and eventually develops into an entirely new species.
Natural selection is a cyclical process that involves the interaction of three elements including inheritance, variation, and reproduction. Sexual reproduction and mutation increase genetic diversity in a species. Inheritance refers to the passing of a person's genetic characteristics to the offspring of that person that includes dominant and recessive alleles. Reproduction is the process of producing viable, fertile offspring. This can be done by both asexual or sexual methods.
Natural selection can only occur when all these elements are in harmony. For instance, if an allele that is dominant at one gene allows an organism to live and reproduce more frequently than the recessive one, the dominant allele will become more common in the population. But if the allele confers a disadvantage in survival or decreases fertility, it will disappear from the population. This process is self-reinforcing meaning that a species with a beneficial trait is more likely to survive and reproduce than an individual with an unadaptive characteristic. The more fit an organism is which is measured by its ability to reproduce and survive, is the more offspring it produces. Individuals with favorable traits, such as having a longer neck in giraffes and bright white patterns of color in male peacocks are more likely to survive and produce offspring, so they will make up the majority of the population over time.
Natural selection only affects populations, not on individual organisms. This is a significant distinction from the Lamarckian theory of evolution which claims that animals acquire traits through use or neglect. For example, if a giraffe's neck gets longer through reaching out to catch prey, its offspring will inherit a longer neck. The differences in neck size between generations will continue to increase until the giraffe becomes unable to reproduce with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles of the same gene are randomly distributed in a group. Eventually, only one will be fixed (become widespread enough to not longer be eliminated through natural selection), and the other alleles will drop in frequency. This can result in an allele that is dominant in extreme. The other alleles are essentially eliminated, and heterozygosity decreases to zero. In a small group, this could result in the complete elimination the recessive gene. This scenario is called the bottleneck effect. It is typical of an evolution process that occurs when the number of individuals migrate to form a group.
A phenotypic bottleneck can also occur when survivors of a disaster like an outbreak or mass hunting event are confined to an area of a limited size. The surviving individuals will be largely homozygous for the dominant allele, meaning that they all have the same phenotype and will therefore have the same fitness characteristics. This may be caused by war, earthquake or even a cholera outbreak. The genetically distinct population, if left susceptible to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from expected values due to differences in fitness. They give a famous instance of twins who are genetically identical, share identical phenotypes but one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift could be vital to the evolution of the species. It is not the only method of evolution. The main alternative is to use a process known as natural selection, where the phenotypic diversity of an individual is maintained through mutation and migration.
Stephens claims that there is a significant distinction between treating drift as a force or cause, and treating other causes like migration and selection as forces and causes. Stephens claims that a causal process account of drift allows us separate it from other forces, and this distinction is essential. He also claims that drift has a direction, that is it tends to eliminate heterozygosity. 에볼루션 코리아 claims that it also has a specific magnitude that is determined by population size.
Evolution through Lamarckism
When high school students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is often referred to as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms by the inheritance of characteristics that are a result of an organism's natural activities, use and disuse. Lamarckism is typically illustrated by the image of a giraffe that extends its neck further to reach leaves higher up in the trees. This would cause giraffes' longer necks to be passed onto their offspring who would then grow even taller.
Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on 17 May 1802, he introduced a groundbreaking concept that radically challenged previous thinking about organic transformation. In his opinion living things 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 offer the subject a thorough and general explanation.
The prevailing story is that Lamarckism became a rival to Charles Darwin's theory of evolution through natural selection and that the two theories fought out in the 19th century. Darwinism eventually triumphed, leading to the development of what biologists today refer to as the Modern Synthesis. This theory denies that acquired characteristics can be inherited, and instead, it argues that organisms develop by the symbiosis of environmental factors, such as natural selection.
Although Lamarck endorsed the idea of inheritance through acquired characters and his contemporaries also offered a few words about this idea however, it was not an integral part of any of their evolutionary theorizing. This is due to the fact that it was never scientifically validated.
It has been more than 200 year since Lamarck's birth and in the field of genomics, there is an increasing body of evidence that supports the heritability of acquired traits. This is also referred to as "neo Lamarckism", or more generally epigenetic inheritance. It is a version of evolution that is just as valid as the more popular Neo-Darwinian theory.
Evolution through adaptation
One of the most common misconceptions about evolution is being driven by a struggle for survival. This notion is not true and overlooks other forces that drive evolution. The struggle for survival is more effectively described as a struggle to survive within a specific environment, which could include not just other organisms but as well the physical environment.
To understand how evolution functions it is beneficial to think about what adaptation is. The term "adaptation" refers to any specific feature that allows an organism to survive and reproduce in its environment. It could be a physical structure, like fur or feathers. Or it can be a behavior trait such as moving towards shade during hot weather, or coming out to avoid the cold at night.
The ability of a living thing to extract energy from its environment and interact with other organisms and their physical environments, is crucial to its survival. The organism must have the right genes for producing offspring, and be able to find sufficient food and resources. In addition, the organism should be capable of reproducing in a way that is optimally within its environmental niche.
These factors, together with mutation and gene flow, lead to an alteration in the percentage of alleles (different forms of a gene) in the gene pool of a population. This shift in the frequency of alleles could lead to the development of new traits and eventually, new species in the course of time.
Many of the features we find appealing in animals and plants are adaptations. For 에볼루션 바카라 무료체험 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 proper understanding of adaptation requires a keen eye to the distinction between behavioral and physiological characteristics.
Physical traits such as thick fur and gills are physical characteristics. Behavior adaptations aren't, such as the tendency of animals to seek companionship or move into the shade during hot weather. In addition it is important to understand that a lack of forethought does not make something an adaptation. Inability to think about the consequences of a decision even if it seems to be rational, could cause it to be unadaptive.