What is Free Evolution?
Free evolution is the notion that natural processes can cause organisms to develop over time. This includes the creation of new species and alteration of the appearance of existing ones.
Many examples have been given of this, including various varieties of stickleback fish that can live in fresh or salt water and walking stick insect varieties that favor specific host plants. These mostly reversible trait permutations however, are not able to explain fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all the living creatures that live on our planet for many centuries. Charles Darwin's natural selection is the most well-known explanation. This is because individuals who are better-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, the population of well-adapted individuals grows and eventually creates a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors that are: 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 traits to his or her offspring, which includes both dominant and recessive alleles. Reproduction is the generation of viable, fertile offspring, which includes both sexual and asexual methods.
Natural selection can only occur when all these elements are in balance. For example, if the dominant allele of one gene allows an organism to live and reproduce more often than the recessive allele, the dominant allele will become more prevalent within the population. If the allele confers a negative survival advantage or reduces the fertility of the population, it will go away. This process is self-reinforcing meaning that an organism with an adaptive trait will live and reproduce more quickly than those with a maladaptive feature. The more fit an organism is which is measured by its ability to reproduce and survive, is the more offspring it will produce. People with good traits, such as having a longer neck in giraffes or bright white patterns of color in male peacocks are more likely to be able to survive and create offspring, which means they will make up the majority of the population over time.
Natural selection only acts on populations, not on individuals. This is a major distinction from the Lamarckian evolution theory that states that animals acquire traits due to the use or absence of use. If a giraffe stretches its neck to catch prey and its neck gets longer, then its offspring will inherit this trait. The difference in neck length between generations will persist until the neck of the giraffe becomes too long that it can not breed with other giraffes.
Evolution through Genetic Drift
In the process of genetic drift, alleles of a gene could be at different frequencies within a population due to random events. At some point, only one of them will be fixed (become common enough to no longer be eliminated by natural selection), and the rest of the alleles will decrease in frequency. In the extreme, this leads to a single allele dominance. The other alleles are eliminated, and heterozygosity falls to zero. In a small number of people, this could result in the complete elimination the recessive gene. Such 에볼루션바카라 would be known as a bottleneck effect and it is typical of the kind of evolutionary process that occurs when a lot of individuals move to form a new group.
A phenotypic 'bottleneck' can also occur when the survivors of a disaster like an outbreak or mass hunt event are concentrated in the same area. 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. The genetically distinct population, if it remains, could be susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew employ a "purely outcome-oriented" definition of drift as any departure from the expected values of variations in fitness. They give a famous instance of twins who are genetically identical, have the exact same phenotype but one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift could play a significant role in the evolution of an organism. However, it is not the only way to progress. Natural selection is the primary alternative, where mutations and migration keep the phenotypic diversity of a population.
Stephens argues there is a vast 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. Stephens claims that a causal process explanation of drift allows us to distinguish it from the other forces, and this distinction is vital. He further argues that drift has both an orientation, i.e., it tends to reduce heterozygosity. our homepage has a size which is determined based on 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 commonly called "Lamarckism" and it asserts that simple organisms evolve into more complex organisms through the inheritance of traits that result from the organism's natural actions use and misuse. Lamarckism can be demonstrated by the giraffe's neck being extended to reach higher leaves in the trees. This could cause the necks of giraffes that are longer to be passed on to their offspring who would grow taller.
Lamarck was a French Zoologist. 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 presented an innovative concept that completely challenged the conventional wisdom about organic transformation. According to Lamarck, living creatures evolved from inanimate materials by a series of gradual steps. Lamarck was not the first to suggest that this could be the case but the general consensus is that he was the one having given the subject its first general and thorough treatment.
The predominant story is that Charles Darwin's theory on natural selection and Lamarckism fought in the 19th century. Darwinism eventually triumphed, leading to the development of what biologists call the Modern Synthesis. The theory argues that acquired characteristics can be inherited, and instead argues that organisms evolve through the selective action of environmental factors, such as natural selection.
While Lamarck endorsed the idea of inheritance through acquired characters, and his contemporaries also spoke of this idea but it was not an integral part of any of their evolutionary theorizing. This is partly because it was never scientifically validated.
It's been more than 200 year since Lamarck's birth and in the field of genomics, there is a growing body of evidence that supports the heritability of acquired traits. This is often called "neo-Lamarckism" or more commonly, epigenetic inheritance. It is a version of evolution that is as valid as the more popular Neo-Darwinian theory.
Evolution through Adaptation
One of the most widespread misconceptions about evolution is that it is driven by a sort of struggle to survive. In reality, this notion is a misrepresentation of natural selection and ignores the other forces that are driving evolution. The struggle for survival is more effectively described as a struggle to survive in a specific environment, which may include not just other organisms but also the physical environment.
Understanding the concept of adaptation is crucial to comprehend evolution. It refers to a specific characteristic that allows an organism to live and reproduce in its environment. It can be a physiological feature, like feathers or fur or a behavior such as a tendency to move to the shade during hot weather or coming out at night to avoid cold.
The ability of an organism to extract energy from its environment and interact with other organisms and their physical environment is essential to its survival. The organism must possess the right genes to produce offspring, and must be able to locate enough food and other resources. The organism should be able to reproduce itself at an amount that is appropriate for its niche.
These factors, along with mutation and gene flow result in a change in the proportion of alleles (different forms of a gene) in a population's gene pool. This shift in the frequency of alleles could lead to the development of new traits and eventually, new species over time.
Many of the features we admire in plants and animals are adaptations. For instance lung or gills that draw oxygen from air, fur and feathers as insulation and long legs to get away from predators, and camouflage to hide. However, a thorough understanding of adaptation requires paying attention to the distinction between physiological and behavioral traits.
Physiological traits like thick fur and gills are physical characteristics. Behavioral adaptations are not like the tendency of animals to seek companionship or retreat into shade during hot weather. It is important to remember that a the absence of planning doesn't result in an adaptation. In fact, failing to consider the consequences of a behavior can make it ineffective, despite the fact that it appears to be reasonable or even essential.