What is Free Evolution?
Free evolution is the idea that the natural processes that organisms go through can lead to their development over time. This includes the creation of new species as well as the change in appearance of existing ones.
A variety of examples have been provided of this, including various kinds 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 typically reversible traits are not able to explain fundamental changes to basic body plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all living organisms that inhabit our planet for many centuries. The best-established explanation is Darwin's natural selection, an evolutionary process that occurs when better-adapted individuals survive and reproduce more successfully than those who are less well-adapted. As time passes, the number of individuals who are well-adapted grows and eventually creates an entirely new species.
Natural selection is an ongoing process that involves the interaction of three factors that are inheritance, variation and reproduction. Sexual reproduction and mutation increase genetic diversity in the species. Inheritance is the term used to describe the transmission of a person's genetic characteristics, which includes recessive and dominant genes and their offspring. Reproduction is the process of generating fertile, viable offspring. This can be accomplished via sexual or asexual methods.
Natural selection only occurs when all these elements are in equilibrium. For instance when a dominant allele at the gene can cause an organism to live and reproduce more frequently than the recessive allele the dominant allele will be more prevalent within the population. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will go away. The process is self-reinforcing which means that an organism with an adaptive trait will survive and reproduce much more than those with a maladaptive trait. The greater an organism's fitness, measured by its ability reproduce and endure, is the higher number of offspring it can produce. Individuals with favorable traits, like having a long neck in giraffes, or bright white color patterns on male peacocks are more likely than others to reproduce and survive which eventually leads to them becoming the majority.
Natural selection is only a force for populations, not on individuals. This is a major distinction from the Lamarckian theory of evolution, which claims that animals acquire traits through use or disuse. For instance, if the giraffe's neck gets longer through reaching out to catch prey its offspring will inherit a longer neck. The difference in neck length between generations will persist until the neck of the giraffe becomes so long that it can no longer breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles of one gene are distributed randomly within a population. At some point, only one of them will be fixed (become common enough to no longer be eliminated by natural selection) and the other alleles drop in frequency. This can lead to an allele that is dominant in the extreme. The other alleles are eliminated, and heterozygosity decreases to zero. In a small group this could lead to the complete elimination the recessive gene. Such a scenario would be known as a bottleneck effect and it is typical of evolutionary process that takes place when a large amount of individuals migrate to form a new population.
A phenotypic bottleneck can also occur when the survivors of a catastrophe, such as an epidemic or a mass hunting event, are concentrated within a narrow area. The survivors will carry an dominant allele, and will have the same phenotype. This situation could be caused by war, earthquakes or even a plague. Whatever the reason the genetically distinct group that is left might be susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from the expected value due to differences in fitness. They cite a famous instance of twins who are genetically identical and have identical phenotypes, but one is struck by lightening and dies while the other lives and reproduces.
This type of drift can play a crucial part in the evolution of an organism. However, it is not the only method to progress. Natural selection is the main alternative, in which mutations and migration maintain phenotypic diversity within the population.
Stephens claims that there is a vast distinction between treating drift as an agent or cause and treating other causes like migration and selection mutation as forces and causes. He argues that a causal process account of drift permits us to differentiate it from the other forces, and that this distinction is vital. He also argues that drift is a directional force: that is it tends to reduce heterozygosity. It also has a size, which is determined by population size.
Evolution through Lamarckism
When high school students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is generally called "Lamarckism" and it states that simple organisms develop into more complex organisms by the inheritance of traits that are a result of the organism's natural actions, use and disuse. Lamarckism can be illustrated by an giraffe's neck stretching to reach higher leaves in the trees. This process would result in giraffes passing on their longer necks to their offspring, who would then become taller.
Lamarck, a French Zoologist from France, presented an innovative idea in his opening lecture at the Museum of Natural History of Paris. He challenged the traditional thinking about organic transformation. In 무료에볼루션 living things had 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 having given the subject its first broad and comprehensive treatment.
The most popular story is that Lamarckism grew into a rival to Charles Darwin's theory of evolutionary natural selection, and that the two theories battled each other in the 19th century. Darwinism ultimately prevailed, leading to what biologists refer to as the Modern Synthesis. This theory denies acquired characteristics 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 endorsed the idea that acquired characters could be passed on to future generations. However, this concept was never a major part of any of their evolutionary theories. This is due to the fact that it was never scientifically validated.
It has been more than 200 years since the birth of Lamarck and in the field of genomics, there is an increasing evidence-based body of evidence to support the heritability acquired characteristics. This is often referred to as "neo-Lamarckism" or more commonly epigenetic inheritance. This is a model that is just as valid as the popular Neodarwinian model.
Evolution through Adaptation
One of the most commonly-held misconceptions about evolution is that it is being driven by a struggle for survival. This notion is not true and overlooks other forces that drive evolution. The struggle for existence is better described as a fight to survive in a specific environment. This could include not only other organisms but also the physical environment itself.
Understanding how adaptation works is essential to comprehend evolution. The term "adaptation" refers to any specific feature that allows an organism to live and reproduce in its environment. It can be a physical feature, like fur or feathers. Or it can be a trait of behavior that allows you to move to the shade during the heat, or escaping the cold at night.
The survival of an organism depends on its ability to obtain energy from the environment and interact with other living organisms and their physical surroundings. The organism should possess the right genes to create offspring and be able find sufficient food and resources. The organism should be able to reproduce itself at the rate that is suitable for its specific niche.
These elements, in conjunction with gene flow and mutation, lead to an alteration in the percentage of alleles (different varieties of a particular gene) in the gene pool of a population. The change in frequency of alleles could lead to the development of novel traits and eventually, new species over time.
Many of the characteristics we find appealing in animals and plants are adaptations. For example lung or gills that draw oxygen from air feathers and fur as insulation and long legs to get away from predators and camouflage to conceal. However, a proper understanding of adaptation requires attention to the distinction between physiological and behavioral traits.
Physical traits such as large gills and thick fur are physical characteristics. Behavior adaptations aren't like the tendency of animals to seek companionship or retreat into shade during hot temperatures. It is important to note that lack of planning does not make an adaptation. Inability to think about the implications of a choice, even if it appears to be rational, may make it unadaptive.