What is Free Evolution?
Free evolution is the concept that the natural processes that organisms go through can cause them to develop over time. This includes the appearance and development of new species.
This has been proven by numerous examples such as the stickleback fish species that can thrive in saltwater or fresh water and walking stick insect varieties that prefer particular host plants. These mostly reversible trait permutations can't, however, be the reason for fundamental changes in body plans.
Evolution through Natural Selection
The evolution of the myriad living organisms on Earth is a mystery that has intrigued scientists for many centuries. Charles Darwin's natural selectivity is the best-established explanation. This is because those who are better adapted survive and reproduce more than those who are less well-adapted. Over time, the population of well-adapted individuals grows and eventually develops into a new species.
Natural selection is a cyclical process that involves the interaction of three factors including inheritance, variation, and reproduction. Variation is caused by mutation and sexual reproduction both of which increase the genetic diversity of a species. Inheritance refers to the passing of a person's genetic characteristics to his or her offspring, which includes both recessive and dominant alleles. Reproduction is the generation of fertile, viable offspring which includes both sexual and asexual methods.
Get Source of these variables must be in balance to allow natural selection to take place. For example when an allele that is dominant at one gene allows an organism to live and reproduce more frequently than the recessive allele the dominant allele will be more prevalent within the population. But if the allele confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. The process is self-reinforcing which means that an organism with an adaptive characteristic will live and reproduce more quickly than one with a maladaptive characteristic. The higher the level of fitness an organism has as measured by its capacity to reproduce and survive, is the greater number of offspring it produces. Individuals with favorable 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 element in the population and not on individuals. This is a major distinction from the Lamarckian evolution theory which holds that animals acquire traits either through usage or inaction. If a giraffe extends its neck to catch prey and its neck gets longer, then the children will inherit this characteristic. The differences in neck size between generations will increase until the giraffe is unable to reproduce with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles from one gene are distributed randomly in a group. In the end, only one will be fixed (become common enough to no longer be eliminated through natural selection), and the rest of the alleles will diminish in frequency. In extreme cases this, it leads to a single allele dominance. Other alleles have been essentially eliminated and heterozygosity has diminished to zero. In a small population this could lead to the complete elimination the recessive gene. click hyperlink is called the bottleneck effect and is typical of the evolution process that occurs when the number of individuals migrate to form a population.
A phenotypic bottleneck may occur when survivors of a catastrophe such as an epidemic or a mass hunting event, are condensed in a limited area. The survivors are likely to be homozygous for the dominant allele, which means that they will all share the same phenotype and will consequently share the same fitness characteristics. This situation might be caused by war, an earthquake or even a cholera outbreak. Whatever the reason the genetically distinct population that remains could be susceptible to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a deviation from the expected values due to differences in fitness. They give a famous example of twins that are genetically identical and have identical phenotypes and yet one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift could be very important in the evolution of the species. But, it's not the only way to evolve. Natural selection is the primary alternative, in which mutations and migrations maintain the phenotypic diversity in a 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 as forces and causes. He claims that a causal mechanism account of drift permits us to differentiate it from other forces, and this distinction is essential. He also claims that drift has a direction, that is it tends to eliminate heterozygosity. It also has a size, that is determined by the size of population.
Evolution through Lamarckism
Biology students in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution is generally called "Lamarckism" and it states that simple organisms grow into more complex organisms via the inherited characteristics that result from the organism's natural actions, use and disuse. Lamarckism is typically illustrated by a picture of a giraffe extending its neck further to reach the higher branches in the trees. This would cause giraffes to pass on their longer necks to offspring, which then become taller.
Lamarck, a French Zoologist from France, presented an idea that was revolutionary in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. According to Lamarck, living creatures evolved from inanimate materials through a series gradual steps. Lamarck wasn't the only one to propose this, but he was widely considered to be the first to provide the subject a thorough and general treatment.
The prevailing story is that Lamarckism became an opponent to Charles Darwin's theory of evolution by natural selection, and that the two theories battled out in the 19th century. Darwinism eventually prevailed, leading to the development of what biologists today call the Modern Synthesis. The theory argues that acquired traits can be passed down through generations and instead, it claims that organisms evolve through the selective influence of environmental elements, like Natural Selection.
While Lamarck believed in the concept of inheritance by acquired characters and his contemporaries also spoke of this idea, it was never a central element in any of their evolutionary theories. This is partly because it was never scientifically validated.
It has been more than 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. It is sometimes called "neo-Lamarckism" or more commonly epigenetic inheritance. This is a version that is as reliable as the popular Neodarwinian model.
Evolution through adaptation
One of the most popular misconceptions about evolution is that it is being driven by a struggle for survival. This view is inaccurate and ignores other forces driving evolution. The struggle for existence is better described as a fight to survive in a specific environment. This can be a challenge for not just other living things, but also the physical surroundings themselves.
To understand how evolution functions it is beneficial to understand what is adaptation. It refers to a specific characteristic that allows an organism to survive and reproduce in its environment. It could be a physiological structure such as fur or feathers, or a behavioral trait such as a tendency to move to the shade during hot weather or stepping out at night to avoid cold.
The capacity of an organism to draw energy from its environment and interact with other organisms and their physical environments is essential to its survival. The organism must have the right genes to produce offspring, and be able to find sufficient food and resources. Moreover, the organism must be capable of reproducing at a high rate within its niche.
These factors, along with gene flow and mutation, lead to changes in the ratio of alleles (different varieties of a particular gene) in the gene pool of a population. The change in frequency of alleles can lead to the emergence of new traits and eventually, new species in the course of time.
Many of the features that we admire about 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 thorough understanding of adaptation requires paying attention to the distinction between behavioral and physiological traits.
Physiological traits like thick fur and gills are physical traits. Behavior adaptations aren't like the tendency of animals to seek companionship or to retreat into the shade during hot weather. It is also important to keep in mind that insufficient planning does not cause an adaptation. Inability to think about the implications of a choice even if it seems to be rational, may make it unadaptive.