What is Free Evolution?
Free evolution is the concept that the natural processes of living organisms can cause them to develop over time. This includes the creation of new species and change in appearance of existing ones.
A variety of examples have been provided of this, such as different varieties of stickleback fish that can be found in fresh or salt water and walking stick insect varieties that are attracted to specific host plants. These mostly reversible traits permutations do not explain the fundamental changes in basic body plans.
Evolution by Natural Selection
The evolution of the myriad living organisms on Earth is a mystery that has fascinated scientists for centuries. The best-established explanation is Charles Darwin's natural selection process, which is triggered when more well-adapted individuals live longer and reproduce more successfully than those less well-adapted. As time passes, a group of well-adapted individuals increases and eventually creates a new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors including reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity of an animal species. Inheritance is the transfer of a person's genetic characteristics to their offspring, which includes both recessive and dominant alleles. Reproduction is the process of producing viable, fertile offspring. This can be achieved via sexual or asexual methods.
All of these variables have to be in equilibrium for natural selection to occur. For instance the case where the dominant allele of the gene causes an organism to survive and reproduce more often than the recessive one, the dominant allele will become more prominent within the population. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will disappear. This process is self-reinforcing which means that an organism with an adaptive trait will survive and reproduce far more effectively than those with a maladaptive feature. The higher the level of fitness an organism has as measured by its capacity to reproduce and endure, is the higher number of offspring it can produce. People with desirable characteristics, like having a longer neck in giraffes and bright white patterns of color in male peacocks are more likely survive and have offspring, so they will make up the majority of the population in the future.
Natural selection is a factor in populations and not on individuals. This is a major distinction from the Lamarckian theory of evolution which claims that animals acquire traits by use or inactivity. For instance, if the animal's neck is lengthened by reaching out to catch prey and its offspring will inherit a more long neck. The difference in neck size between generations will continue to increase until the giraffe is unable to breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, alleles within a gene can reach different frequencies in a group through random events. In the end, one will reach fixation (become so widespread that it can no longer be removed by natural selection) and other alleles fall to lower frequencies. In extreme cases it can lead to one allele dominance. The other alleles are essentially eliminated, and heterozygosity is reduced to zero. In a small population, this could lead to the total elimination of recessive allele. This is known as the bottleneck effect and is typical of an evolutionary process that occurs when a large number individuals migrate to form a population.
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 survivors will be mostly homozygous for the dominant allele, which means they will all have the same phenotype, and therefore have the same fitness characteristics. This could be caused by earthquakes, war or even plagues. Regardless of the cause the genetically distinct group that is left might be susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a departure from expected values due to differences in fitness. They provide a well-known example of twins that are genetically identical, share the exact same phenotype and yet one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift could be vital to the evolution of a species. It is not the only method of evolution. Natural selection is the most common alternative, where mutations and migration keep phenotypic diversity within a population.
Stephens claims that there is a significant difference between treating the phenomenon of drift as an actual cause or force, and treating other causes like migration and selection mutation as causes and forces. He argues that a causal-process model of drift allows us to distinguish it from other forces, and this differentiation is crucial. He further argues that drift is a directional force: that is it tends to reduce heterozygosity. It also has a magnitude, 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, also called "Lamarckism is based on the idea that simple organisms evolve into more complex organisms adopting traits that result from the use and abuse of an organism. Lamarckism is typically illustrated with a picture of a giraffe stretching its neck further to reach leaves higher up in the trees. This could cause giraffes to pass on their longer necks to their offspring, who would then get taller.
Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on the 17th of May in 1802, he introduced a groundbreaking concept that radically challenged the previous understanding of organic transformation. According to Lamarck, living creatures evolved from inanimate matter through a series gradual steps. Lamarck wasn't the first to make this claim, but he was widely regarded as the first to provide the subject a comprehensive and general treatment.
The dominant story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were rivals during the 19th century. Darwinism ultimately prevailed and led to what biologists refer to as the Modern Synthesis. This theory denies acquired characteristics are passed down from generation to generation and instead, it claims that organisms evolve through the influence of environment factors, including Natural Selection.
While Lamarck believed in the concept of inheritance by acquired characters and his contemporaries also paid lip-service to this notion, it was never a central element in any of their theories about evolution. This is partly due to the fact that it was never validated 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 to support the heritability of acquired characteristics. This is often called "neo-Lamarckism" or more frequently, epigenetic inheritance. It is a form of evolution that is just as valid as the more popular neo-Darwinian model.
Evolution through Adaptation
One of the most commonly-held misconceptions about evolution is being driven by a struggle to survive. In fact, this view is inaccurate and overlooks the other forces that drive evolution. The fight for survival is better described as a fight to survive in a specific environment. This may be a challenge for not just other living things as well as the physical environment.
Understanding adaptation is important to understand evolution. The term "adaptation" refers to any specific feature that allows an organism to live and reproduce within its environment. It can be a physiological structure, such as fur or feathers, or a behavioral trait, such as moving to the shade during the heat or leaving at night to avoid the cold.
The survival of an organism is dependent on its ability to obtain energy from the environment and interact with other organisms and their physical environments. The organism must possess the right genes to create offspring, and it should be able to access sufficient food and other resources. The organism must also be able to reproduce itself at the rate that is suitable for its particular niche.
These factors, in conjunction with mutations and gene flow can cause a shift in the proportion of different alleles in the gene pool of a population. This shift in the frequency of alleles can lead to the emergence of novel traits and eventually new species in the course of time.
Many of the features we appreciate in animals and plants are adaptations. For instance the lungs or gills which draw oxygen from air, fur and feathers as insulation and long legs to get away from predators, and camouflage to hide. To understand adaptation it is essential to distinguish between behavioral and physiological traits.
Physiological traits like large gills and thick fur are physical characteristics. Behavior adaptations aren't, such as the tendency of animals to seek companionship or retreat into shade in hot weather. 에볼루션 바카라 체험 is also important to note that lack of planning does not cause an adaptation. In fact, failure to consider the consequences of a decision can render it ineffective even though it may appear to be reasonable or even essential.