What is Free Evolution?
Free evolution is the idea that the natural processes that organisms go through can cause them to develop over time. This includes the appearance and growth of new species.
Numerous examples have been offered of this, including various varieties of fish called sticklebacks that can be found in salt or fresh water, as well as walking stick insect varieties that are attracted to particular host plants. These mostly reversible trait permutations can't, however, explain fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all the living organisms that inhabit our planet for many centuries. The most widely accepted explanation is that of Charles Darwin's natural selection, which occurs when individuals that are better adapted survive and reproduce more successfully than those less well adapted. As time passes, the number of individuals who are well-adapted grows and eventually creates a new species.
Natural selection is a cyclical process that is characterized by the interaction of three elements: variation, inheritance and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity of an animal species. Inheritance is the transfer of a person's genetic characteristics to their offspring, which includes both dominant and recessive alleles. Reproduction is the process of creating viable, fertile offspring. This can be achieved via sexual or asexual methods.
All of these elements have to be in equilibrium to allow natural selection to take place. If, for instance, a dominant gene allele allows an organism to reproduce and survive more than the recessive gene allele, then the dominant allele will become more prevalent in a group. If the allele confers a negative survival advantage or lowers the fertility of the population, it will go away. This process is self-reinforcing, which means that an organism that has an adaptive trait will survive and reproduce far more effectively than those with a maladaptive trait. The greater an organism's fitness, measured by its ability reproduce and survive, is the greater number of offspring it will produce. People with good traits, like longer necks in giraffes and bright white patterns of color in male peacocks are more likely to survive and produce offspring, so they will eventually make up the majority of the population over time.
Natural selection is only an element in the population and not on individuals. This is an important distinction from the Lamarckian theory of evolution, which claims that animals acquire characteristics through use or neglect. For instance, if the animal's neck is lengthened by stretching to reach prey and its offspring will inherit a larger neck. The difference in neck size between generations will continue to grow until the giraffe is no longer able to reproduce with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles from one gene are distributed randomly in a group. Eventually, one of them will reach fixation (become so widespread that it is unable to be eliminated by natural selection), while the other alleles drop to lower frequency. This can lead to dominance in extreme. The other alleles are essentially eliminated and heterozygosity has diminished to zero. In a small population it could lead to the complete elimination of recessive allele. This scenario is called the bottleneck effect. It is typical of an evolution process that occurs when an enormous number of individuals move to form a population.
A phenotypic bottleneck could occur when survivors of a catastrophe, such as an epidemic or a mass hunting event, are concentrated in a limited area. The survivors will be mostly homozygous for the dominant allele which means that they will all share the same phenotype and therefore share the same fitness characteristics. This could be caused by war, earthquake or even a cholera outbreak. Whatever the reason, the genetically distinct population that is left might be prone to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a deviation from the expected values due to differences in fitness. They give the famous example of twins who are both genetically identical and share the same phenotype. However one is struck by lightning and dies, but the other is able to reproduce.
This type of drift is vital to the evolution of an entire species. It is not the only method of evolution. The main alternative is to use a process known as natural selection, where the phenotypic variation of a population is maintained by mutation and migration.
Stephens argues there is a vast difference between treating the phenomenon of drift as a force or cause, and considering other causes, such as migration and selection as forces and causes. He argues that a causal-process account of drift allows us differentiate it from other forces, and this distinction is crucial. He also argues that drift is a directional force: that is it tends to reduce heterozygosity. He also claims that it also has a magnitude, which is determined by the size of population.
Evolution through Lamarckism
Biology students in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. 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 result from an organism's natural activities use and misuse. Lamarckism is typically illustrated with the image of a giraffe that extends its neck further to reach higher up in the trees. This process would result in giraffes passing on their longer necks to 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 the 17th of May in 1802, he presented an original idea that fundamentally challenged the conventional wisdom about organic transformation. According to 에볼루션 사이트 , living things evolved from inanimate materials by a series of gradual steps. Lamarck wasn't the only one to make this claim, but he was widely thought of as the first to give the subject a comprehensive and general treatment.
The predominant story is that Charles Darwin's theory on evolution by natural selection and Lamarckism fought in the 19th Century. Darwinism ultimately won and led to what biologists call the Modern Synthesis. The theory argues that acquired traits are passed down from generation to generation and instead argues that organisms evolve through the influence of environment factors, such as Natural Selection.
Lamarck and his contemporaries supported the notion that acquired characters could be passed down to future generations. However, this idea was never a key element of any of their theories about evolution. This is partly 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 vast amount of evidence that supports the possibility of inheritance of acquired traits. This is referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a model that is as reliable as the popular neodarwinian model.
Evolution by adaptation
One of the most commonly-held misconceptions about evolution is being driven by a struggle to survive. This view is inaccurate and overlooks other forces that drive evolution. The fight for survival can be more effectively described as a struggle to survive within a particular environment, which could be a struggle that involves not only other organisms, but as well the physical environment.
Understanding the concept of adaptation is crucial to understand evolution. It refers to a specific feature that allows an organism to survive and reproduce in its environment. It can be a physiological structure, like feathers or fur, or a behavioral trait like moving into the shade in the heat or leaving at night to avoid cold.
The survival of an organism depends on its ability to obtain 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. The organism should also be able reproduce itself at the rate that is suitable for its niche.
These elements, in conjunction with mutation and gene flow, lead to a change in the proportion of alleles (different types of a gene) in the population's gene pool. This shift in the frequency of alleles can result in 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 proper understanding of adaptation requires attention to the distinction between physiological and behavioral traits.
무료 에볼루션 like thick fur or gills, are physical characteristics, whereas behavioral adaptations, such as the tendency to search for companions or to move to shade in hot weather, aren't. It is important to keep in mind that lack of planning does not cause an adaptation. A failure to consider the implications of a choice even if it appears to be rational, could make it inflexible.