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 as well as the alteration of the appearance of existing ones.
A variety of examples have been provided of this, including different kinds of stickleback fish that can live in either salt or fresh water, as well as walking stick insect varieties that are attracted to specific host plants. These reversible traits do not explain the fundamental changes in the basic body plan.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is an enigma that has fascinated scientists for decades. Charles Darwin's natural selection is the best-established explanation. This process occurs when individuals who are better-adapted survive and reproduce more 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 a process that is cyclical and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Mutation and sexual reproduction increase genetic diversity in a species. Inheritance refers the transmission of genetic traits, including recessive and dominant genes, to their offspring. Reproduction is the process of creating fertile, viable offspring. This can be done by both asexual or sexual methods.
All of these variables have to be in equilibrium to allow natural selection to take place. For instance, if the dominant allele of a gene allows an organism to live and reproduce more often than the recessive one, the dominant allele will become more prevalent within the population. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will go away. The process is self-reinforced, which means that an organism that has a beneficial trait will survive and reproduce more than an individual with an unadaptive characteristic. The more offspring that an organism has, the greater its fitness which is measured by its capacity to reproduce itself and survive. People with good characteristics, such as the long neck of giraffes, or bright white patterns on male peacocks are more likely to others to survive and reproduce and eventually lead to them becoming the majority.
Natural selection is only a force for populations, not individual organisms. This is a crucial distinction from the Lamarckian theory of evolution that states that animals acquire traits due to the use or absence of use. For instance, if a Giraffe's neck grows longer due to reaching out to catch prey its offspring will inherit a larger neck. The differences in neck size between generations will continue to increase until the giraffe becomes unable to reproduce with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles within a gene can be at different frequencies in a group through random events. At some point, only one of them will be fixed (become common enough that it can no longer be eliminated by natural selection), and the rest of the alleles will decrease in frequency. In extreme cases, this leads to a single allele dominance. 에볼루션사이트 are essentially eliminated, and heterozygosity falls to zero. In a small population, this could result in the complete elimination of recessive gene. This is known as the bottleneck effect and is typical of the evolutionary process that occurs when a large number individuals migrate to form a group.
A phenotypic bottleneck can also occur when the survivors of a catastrophe such as an outbreak or mass hunting incident are concentrated in a small area. The remaining individuals will be largely homozygous for the dominant allele, which means that they will all have the same phenotype and will consequently share the same fitness characteristics. This situation could be caused by earthquakes, war, or even plagues. Whatever the reason the genetically distinct group that remains could be susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a departure from expected values due to differences in fitness. They cite the famous example of twins who are genetically identical and share the same phenotype, but one is struck by lightning and dies, whereas the other continues to reproduce.
This type of drift is vital to the evolution of a species. This isn't the only method for evolution. The main alternative is to use a process known as natural selection, in which the phenotypic diversity of a population is maintained by mutation and migration.
Stephens argues there is a significant distinction between treating drift as an actual cause or force, and treating other causes such as migration and selection mutation as forces and causes. Stephens claims that a causal process model of drift allows us to separate it from other forces and this differentiation is crucial. He argues further that drift has a direction, i.e., it tends to eliminate heterozygosity. It also has a size that is determined by population size.
Evolution through Lamarckism
Students of biology in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, often called "Lamarckism which means that simple organisms transform into more complex organisms through inheriting characteristics that are a product of an organism's use and disuse. Lamarckism can be illustrated by the giraffe's neck being extended to reach higher leaves in the trees. This causes the necks of giraffes that are longer to be passed onto their offspring who would then grow even taller.
Lamarck the French Zoologist, introduced a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. According to him living things evolved from inanimate matter through an escalating series of steps. Lamarck wasn't the first to suggest this but he was considered to be the first to offer the subject a thorough and general overview.
The dominant story is that Charles Darwin's theory on evolution by natural selection and Lamarckism were competing in the 19th century. Darwinism eventually prevailed and led to the creation of what biologists refer to as the Modern Synthesis. The theory argues that acquired traits can be passed down through generations and instead argues organisms evolve by the selective action of environment elements, like Natural Selection.
Although 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 evolutionary theorizing. This is largely due to the fact that it was never validated scientifically.
But it is now more than 200 years since Lamarck was born and in the age of genomics there is a huge amount of evidence to support the heritability of acquired characteristics. This is referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a variant that is as valid as the popular neodarwinian model.
Evolution by Adaptation
One of the most commonly-held misconceptions about evolution is its being driven by a fight for survival. This view is inaccurate and overlooks other forces that drive evolution. The struggle for existence is more accurately described as a struggle to survive in a particular environment. This may include not only other organisms as well as the physical environment.
To understand how evolution functions it is important to consider what adaptation is. The term "adaptation" refers to any characteristic that allows a living thing to survive in its environment and reproduce. It can be a physical structure like feathers or fur. It could also be a trait of behavior that allows you to move to the shade during hot weather or coming out to avoid the cold at night.
The survival of an organism depends on its ability to draw energy from the surrounding environment and interact with other organisms and their physical environments. The organism must have the right genes to create offspring and be able find sufficient food and resources. The organism should also be able reproduce itself at an amount that is appropriate for its specific niche.
These elements, in conjunction with gene flow and mutation, lead to changes in the ratio of alleles (different varieties of a particular gene) in the population's gene pool. As time passes, this shift in allele frequencies can result in the development of new traits and eventually new species.
Many of the characteristics 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 long legs to run away from predators and camouflage for hiding. However, a proper understanding of adaptation requires a keen eye to the distinction between the physiological and behavioral characteristics.
Physiological adaptations, like thick fur or gills, are physical traits, while behavioral adaptations, like the desire to find companions or to retreat into the shade in hot weather, aren't. Additionally, it is important to remember that a lack of forethought is not a reason to make something an adaptation. In fact, failure to consider the consequences of a decision can render it unadaptive even though it may appear to be sensible or even necessary.