What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to evolve over time. This includes the appearance and development of new species.
A variety of examples have been provided of this, such as different varieties of stickleback fish that can be found in salt or fresh water, and walking stick insect varieties that favor particular host plants. These mostly reversible traits permutations are not able to explain fundamental changes to basic body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all living creatures that inhabit our planet for ages. visit -established explanation is Darwin's natural selection, a process that occurs when individuals that are better adapted survive and reproduce more successfully than those who are less well adapted. As time passes, a group of well-adapted individuals expands and eventually creates a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors: variation, reproduction and inheritance. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity of an animal species. Inheritance is the transfer of a person's genetic characteristics to his or her offspring, which includes both dominant and recessive alleles. Reproduction is the process of generating fertile, viable offspring. This can be achieved via sexual or asexual methods.
Natural selection only occurs when all the factors are in balance. If, for example the dominant gene allele allows an organism to reproduce and last longer than the recessive gene allele, then the dominant allele will become more common in a population. However, if the gene confers an unfavorable survival advantage or reduces fertility, it will be eliminated from the population. The process is self reinforcing, which means that an organism that has an adaptive trait will live 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 endure, is the higher number of offspring it can produce. Individuals with favorable traits, like longer necks in giraffes and bright white colors in male peacocks are more likely survive and produce offspring, so they will eventually make up the majority of the population in the future.
Natural selection is an element in the population and not on individuals. This is a major distinction from the Lamarckian theory of evolution which states that animals acquire characteristics through use or neglect. For example, if a animal's neck is lengthened by reaching out to catch prey its offspring will inherit a larger neck. The difference in neck length between generations will continue until the neck of the giraffe becomes too long to no longer breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of one gene are distributed randomly within a population. At some point, one will reach fixation (become so widespread that it can no longer be removed by natural selection), while other alleles fall to lower frequencies. In extreme cases this, it leads to dominance of a single allele. The other alleles have been virtually eliminated and heterozygosity decreased to a minimum. In a small group it could lead to the complete elimination of the recessive allele. This scenario is known as a bottleneck effect and it is typical of the kind of evolutionary process that occurs when a large amount of people migrate to form a new group.
A phenotypic bottleneck could happen when the survivors of a catastrophe like an epidemic or a mass hunting event, are condensed in a limited area. The survivors will carry an allele that is dominant and will have the same phenotype. This could be caused by war, an earthquake or even a disease. The genetically distinct population, if it remains susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew utilize 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 lightening and dies while the other lives and reproduces.
This kind of drift could play a crucial role in the evolution of an organism. It's not the only method for evolution. Natural selection is the primary alternative, in which mutations and migrations maintain the phenotypic diversity of the population.
Stephens argues that there is a significant difference between treating the phenomenon of drift as a force, or a cause and considering other causes of evolution, such as mutation, selection and migration as forces or causes. He claims that a causal mechanism account of drift allows us to distinguish it from the other forces, and that this distinction is essential. He also argues that drift is both an orientation, i.e., it tends to reduce heterozygosity. It also has a size, that is determined by the size of the population.
Evolution by Lamarckism
Biology students in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, also called "Lamarckism which means that simple organisms transform into more complex organisms adopting traits that result from an organism's use and disuse. Lamarckism is typically illustrated by a picture of a giraffe that extends its neck to reach leaves higher up in the trees. This could cause giraffes to give their longer necks to their offspring, which then grow even taller.
Lamarck was a French Zoologist. In his lecture to begin his course on invertebrate zoology held at the Museum of Natural History in Paris on 17 May 1802, he introduced a groundbreaking concept that radically challenged the conventional wisdom about organic transformation. In his view, living things had evolved from inanimate matter through a series of gradual steps. Lamarck was not the only one to suggest that this could be the case, but his reputation is widely regarded as being the one who gave the subject its first general and comprehensive treatment.
The most popular story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were competing in the 19th century. Darwinism ultimately prevailed which led to what biologists call the Modern Synthesis. This theory denies acquired characteristics can be passed down and instead argues organisms evolve by the influence of environment factors, such as Natural Selection.
Although Lamarck supported the notion of inheritance through acquired characters and his contemporaries paid lip-service to this notion but it was not a major feature in any of their evolutionary theorizing. This is largely due to the fact that it was never validated scientifically.
It has been more than 200 years since the birth of Lamarck and in the field of age genomics, there is an increasing evidence base that supports the heritability acquired characteristics. It is sometimes called "neo-Lamarckism" or more frequently epigenetic inheritance. It is a form of evolution that is just as relevant as the more popular neo-Darwinian model.
Evolution through the process of adaptation
One of the most widespread misconceptions about evolution is that it is driven by a type of struggle for survival. In fact, this view is inaccurate and overlooks the other forces that drive evolution. The struggle for survival is more effectively described as a struggle to survive within a particular environment, which could be a struggle that involves not only other organisms but as well the physical environment.
To understand how evolution operates, it is helpful to understand what is adaptation. Adaptation refers to any particular feature that allows an organism to live and reproduce within its environment. It can be a physiological structure such as feathers or fur or a behavior, such as moving to the shade during hot weather or stepping out at night to avoid the cold.
The ability of an organism to extract energy from its environment and interact with other organisms and their physical environments, is crucial to its survival. The organism must possess the right genes to generate offspring, and must be able to access sufficient food and other resources. The organism must also be able to reproduce itself at a rate that is optimal for its niche.
These factors, along with mutation and gene flow can result in an alteration in the percentage of alleles (different forms of a gene) in the population's gene pool. This change in allele frequency can lead to the emergence of new traits, and eventually new species in the course of time.
Many of the features we admire in animals and plants are adaptations. For instance lung or gills that extract oxygen from the air feathers and fur as insulation and long legs to get away from predators and camouflage for hiding. However, a thorough understanding of adaptation requires a keen eye to the distinction between behavioral and physiological characteristics.
Physiological adaptations, such as thick fur or gills, are physical traits, whereas behavioral adaptations, such as the desire to find companions or to move to shade in hot weather, aren't. It is important to keep in mind that insufficient planning does not result in an adaptation. In fact, a failure to consider the consequences of a choice can render it unadaptive, despite the fact that it appears to be reasonable or even essential.