What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to develop over time. This includes the emergence and development of new species.
A variety of examples have been provided of this, such as different varieties of stickleback fish that can live in either salt or fresh water, as well as walking stick insect varieties that favor specific host plants. These are mostly reversible traits however, are not able to explain fundamental changes in basic body plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all the living creatures that inhabit our planet for centuries. Charles Darwin's natural selectivity is the best-established explanation. This process occurs when those who are better adapted have more success in reproduction and survival than those who are less well-adapted. Over time, a community of well-adapted individuals expands and eventually creates a new species.
Natural selection is a process that is cyclical and involves the interaction of three factors: variation, reproduction and inheritance. Sexual reproduction and mutation increase genetic diversity in an animal species. Inheritance is the transfer of a person's genetic characteristics to the offspring of that person which includes both dominant and recessive alleles. Reproduction is the generation of fertile, viable offspring which includes both sexual and asexual methods.
Natural selection is only possible when all of these factors are in balance. For instance the case where a dominant allele at one gene causes an organism to survive and reproduce more often than the recessive allele, the dominant allele will be more prevalent within the population. However, if the gene confers an unfavorable survival advantage or reduces fertility, it will disappear from the population. 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 higher the level of fitness an organism has which is measured by its ability to reproduce and survive, is the greater number of offspring it will produce. People with good traits, like having a long neck in giraffes, or bright white patterns on male peacocks, are more likely than others to live and reproduce and eventually lead to them becoming the majority.
Natural selection is an aspect of populations and not on individuals. This is a significant distinction from the Lamarckian theory of evolution, which argues that animals acquire characteristics through use or disuse. If a giraffe expands its neck to catch prey, and the neck becomes longer, then the offspring will inherit this characteristic. The differences in neck length between generations will continue until the giraffe's neck becomes too long that it can not breed with other giraffes.
바카라 에볼루션 by Genetic Drift
Genetic drift occurs when alleles from the same gene are randomly distributed within a population. In the end, one will reach fixation (become so widespread that it cannot be eliminated through natural selection), while other alleles will fall to lower frequency. In the extreme this, it leads to dominance of a single allele. Other alleles have been essentially eliminated and heterozygosity has decreased to zero. In a small number of people this could result in the complete elimination of recessive alleles. This scenario is known as a bottleneck effect and it is typical of evolutionary process that takes place when a lot of individuals move to form a new group.
A phenotypic bottleneck may also occur when the survivors of a catastrophe like an outbreak or mass hunting event are confined to an area of a limited size. The survivors are likely to be homozygous for the dominant allele which means that they will all have the same phenotype, and thus share the same fitness characteristics. This could be caused by earthquakes, war or even a plague. The genetically distinct population, if left, could 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 give the famous example of twins that are genetically identical and have exactly the same phenotype. However, one is struck by lightning and dies, while the other is able to reproduce.
This kind of drift can be very important in the evolution of the species. It is not the only method of evolution. The most common alternative is a process known as natural selection, in which the phenotypic variation of a population is maintained by mutation and migration.
Stephens claims that there is a huge difference between treating drift like an agent 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 to distinguish it from other forces, and this distinction is crucial. He also claims that drift has a direction, that is, it tends to eliminate heterozygosity, and that it also has a size, which is determined by the size of the population.
Evolution by Lamarckism
Biology students in high school are often introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution, also called "Lamarckism which means that simple organisms evolve into more complex organisms through inheriting characteristics that are a product of the organism's use and misuse. Lamarckism is typically illustrated with the image of a giraffe that extends its neck longer to reach the higher branches in the trees. This would cause the necks of giraffes that are longer to be passed onto their offspring who would grow taller.
Lamarck was a French Zoologist. In his lecture to begin his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th May 1802, he introduced a groundbreaking concept that radically challenged the conventional wisdom about organic transformation. In his opinion living things evolved from inanimate matter via the gradual progression of events. Lamarck was not the only one to suggest that this might be the case but the general consensus is that he was the one being the one who gave the subject his first comprehensive and comprehensive treatment.
The popular narrative is that Lamarckism grew into a rival to Charles Darwin's theory of evolution through natural selection, and both theories battled it out in the 19th century. Darwinism eventually won and led to the development of what biologists refer to as the Modern Synthesis. The theory argues that acquired traits are passed down from generation to generation and instead, it claims that organisms evolve through the selective action of environment elements, like Natural Selection.
Lamarck and his contemporaries supported the notion that acquired characters could be passed down to future generations. However, this notion was never a key element of any of their theories about evolution. This is due to the fact that it was never scientifically validated.
It's been over 200 year since Lamarck's birth and in the field of genomics there is a growing evidence-based body of evidence to support the heritability acquired characteristics. This is also known as "neo Lamarckism", or more generally epigenetic inheritance. This is a model that is just as valid as the popular Neodarwinian model.
Evolution by Adaptation
One of the most popular misconceptions about evolution is that it is driven by a sort of struggle to survive. This view is inaccurate and ignores other forces driving evolution. The struggle for existence is more accurately described as a struggle to survive in a specific environment. This can include not only other organisms as well as the physical environment itself.
Understanding the concept of adaptation is crucial to understand evolution. Adaptation refers to any particular characteristic that allows an organism to live and reproduce within its environment. It could be a physical feature, like fur or feathers. Or it can be a trait of behavior that allows you to move into the shade during hot weather, or moving out to avoid the cold at night.
The capacity of an organism to draw energy from its surroundings and interact with other organisms as well as their physical environments, is crucial to its survival. The organism must have the right genes to create offspring, and it should be able to access enough food and other resources. Moreover, the organism must be able to reproduce itself at a high rate within its environment.
These factors, together with mutation and gene flow, lead to changes in the ratio of alleles (different varieties of a particular gene) in the population's gene pool. This change in allele frequency can result in the emergence of new traits, and eventually new species over time.
A lot of the traits we admire in animals and plants are adaptations, for example, lungs or gills to extract oxygen from the air, feathers or fur to provide insulation and long legs for running away from predators and camouflage for hiding. However, a proper understanding of adaptation requires attention to the distinction between physiological and behavioral traits.
Physiological traits like thick fur and gills are physical characteristics. Behavioral adaptations are not, such as the tendency of animals to seek companionship or move into the shade during hot weather. Additionally, it is important to remember that a lack of forethought does not mean that something is an adaptation. A failure to consider the consequences of a decision, even if it appears to be rational, could make it unadaptive.