What is Free Evolution?
Free evolution is the concept that natural processes can lead to the development of organisms over time. This includes the development of new species as well as the alteration of the appearance of existing species.
A variety of examples have been provided of this, such as different varieties of fish called sticklebacks that can live in salt or fresh water, and walking stick insect varieties that favor specific host plants. These mostly reversible trait permutations however, are not able to explain fundamental changes in body plans.
Evolution through Natural Selection
The development of the myriad of living organisms on Earth is a mystery that has intrigued scientists for centuries. Charles Darwin's natural selection theory is the best-established explanation. This process occurs when individuals who are better-adapted have more success in reproduction and survival than those who are less well-adapted. As time passes, a group of well adapted individuals grows and eventually forms a whole new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity of an animal species. Inheritance refers to the passing of a person's genetic characteristics to their offspring, which includes both dominant and recessive alleles. Reproduction is the process of creating viable, fertile offspring. This can be achieved via sexual or asexual methods.
Natural selection is only possible when all the factors are in balance. For instance, if a dominant allele at the gene allows an organism to live and reproduce more frequently than the recessive allele the dominant allele will become more prevalent within the population. However, if the gene confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. The process is self reinforcing meaning that the organism with an adaptive characteristic will live and reproduce much more than one with a maladaptive characteristic. The more offspring that an organism has the more fit it is which is measured by its ability to reproduce itself and survive. People with good traits, like a long neck in the giraffe, or bright white color 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 an important distinction from the Lamarckian theory of evolution, which states that animals acquire traits through use or disuse. For example, if a giraffe's neck gets longer through stretching to reach prey, its offspring will inherit a longer neck. The length difference between generations will persist until the giraffe's neck gets too long that it can no longer breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles from a gene are randomly distributed within a population. In the end, only one will be fixed (become common enough to no more be eliminated through natural selection), and the other alleles will decrease in frequency. This can lead to a dominant allele at the extreme. The other alleles have been basically eliminated and heterozygosity has decreased to zero. In a small number of people this could result in the total elimination of recessive alleles. This is known as the bottleneck effect. It is typical of an evolutionary process that occurs whenever the number of individuals migrate to form a group.
A phenotypic bottleneck may also occur when survivors of a disaster such as an outbreak or mass hunting incident are concentrated in the same area. The survivors are likely to be homozygous for the dominant allele, meaning that they all share the same phenotype and thus share the same fitness characteristics. This could be the result of a conflict, earthquake or even a cholera outbreak. Whatever the reason the genetically distinct population that remains could be susceptible to genetic drift.
Walsh, Lewens, and Ariew use a "purely outcome-oriented" definition of drift as any deviation from the expected values for different fitness levels. They give a famous instance of twins who are genetically identical, have identical phenotypes but one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift could be vital to the evolution of a species. But, it's not the only way to progress. Natural selection is the main alternative, where mutations and migrations maintain phenotypic diversity within a population.
Stephens claims that there is a vast distinction between treating drift as a force or cause, and treating other causes like selection mutation and migration as causes and forces. He claims that a causal-process explanation of drift lets us differentiate it from other forces and this distinction is crucial. He argues further that drift is both an orientation, i.e., it tends towards eliminating heterozygosity. It also has a size, which is determined based on population size.
Evolution by Lamarckism
When students in high school take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, also referred to as "Lamarckism, states that simple organisms evolve into more complex organisms through inheriting characteristics that result from the organism's use and misuse. Lamarckism can be illustrated by a giraffe extending its neck to reach higher levels of leaves in the trees. This could cause giraffes to give their longer necks to their offspring, who then get taller.
Lamarck Lamarck, a French Zoologist, introduced a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. According Lamarck, living organisms evolved from inanimate materials through a series gradual steps. Lamarck wasn't the only one to make this claim but he was thought of as the first to give the subject a comprehensive and general overview.
The most popular story is that Charles Darwin's theory on natural selection and Lamarckism were rivals in the 19th century. Darwinism eventually triumphed, leading to the development of what biologists now refer to as the Modern Synthesis. The theory denies that acquired characteristics can be passed down through generations and instead argues that organisms evolve through the selective influence of environmental factors, such as 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 central part of any of their evolutionary theories. This is due to the fact that it was never scientifically tested.
It's been more than 200 years since the birth of Lamarck, and in the age genomics, there is an increasing evidence-based body of evidence to support the heritability of acquired traits. It is sometimes referred to as "neo-Lamarckism" or more often, epigenetic inheritance. It is a variant of evolution that is just as relevant as the more popular neo-Darwinian model.
Evolution by Adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle to survive. In reality, this notion is a misrepresentation of natural selection and ignores the other forces that drive evolution. The struggle for survival is more effectively described as a struggle to survive within a specific environment, which can involve not only other organisms but also the physical environment.
To understand how evolution operates it is important to understand what is adaptation. Adaptation refers to any particular feature that allows an organism to live and reproduce in its environment. weblink could be a physiological structure such as feathers or fur, or a behavioral trait, such as moving to the shade during the heat or leaving at night to avoid cold.
An organism's survival depends on its ability to obtain energy from the environment and to interact with other organisms and their physical environments. The organism must have the right genes for producing offspring and be able find enough food and resources. The organism must also be able to reproduce itself at the rate that is suitable for its particular niche.
These factors, together with mutation and gene flow can result in an alteration in the percentage of alleles (different types of a gene) in the gene pool of a population. As time passes, this shift in allele frequencies could result in the emergence of new traits, and eventually new species.
Many of the characteristics we admire in animals and plants are adaptations. For instance lung or gills that draw oxygen from air feathers and fur for insulation, long legs to run away from predators and camouflage for hiding. However, a complete understanding of adaptation requires a keen eye to the distinction between behavioral and physiological characteristics.
Physiological adaptations, like 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. In addition, it is important to remember that a lack of thought does not make something an adaptation. In fact, failing to think about the consequences of a choice can render it ineffective despite the fact that it may appear to be sensible or even necessary.