What is Free Evolution?
Free evolution is the notion that the natural processes of organisms can cause them to develop over time. This includes the evolution of new species as well as the alteration of the appearance of existing species.
This has been demonstrated by many examples such as the stickleback fish species that can live in fresh or saltwater and walking stick insect types that are apprehensive about particular host plants. These mostly reversible traits permutations cannot explain fundamental changes to the body's basic plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all the living organisms that inhabit our planet for centuries. Charles Darwin's natural selection is the most well-known explanation. This is because people who are more well-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 an ongoing process and involves the interaction of three factors including reproduction, variation and inheritance. Mutation and sexual reproduction increase the genetic diversity of the species. Inheritance is the term used to describe the transmission of a person's genetic traits, which include both dominant and recessive genes to their offspring. Reproduction is the process of producing fertile, viable offspring, which includes both sexual and asexual methods.
All of these factors have to be in equilibrium for natural selection to occur. If, for example the dominant gene allele allows an organism to reproduce and last longer than the recessive gene, then the dominant allele will become more prevalent in a group. But if the allele confers an unfavorable survival advantage or reduces fertility, it will be eliminated from the population. This 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 an organism produces the more fit it is, which is measured by its capacity to reproduce and survive. People with good traits, such as having a longer neck in giraffes and bright white color patterns in male peacocks are more likely be able to survive and create offspring, which means they will make up the majority of the population over time.
Natural selection only acts on populations, not individuals. This is a significant distinction from the Lamarckian evolution theory that states that animals acquire traits due to the use or absence of use. If a giraffe extends its neck to catch prey and the neck grows longer, then its offspring will inherit this characteristic. The difference in neck length between generations will persist until the giraffe's neck gets so long that it can no longer breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, the alleles of a gene could be at different frequencies within a population by chance events. In the end, only one will be fixed (become common enough that it can no longer be eliminated through natural selection) and the rest of the alleles will diminish in frequency. In extreme cases this, it leads to one allele dominance. The other alleles have been virtually eliminated and heterozygosity diminished to zero. In a small group this could lead to the complete elimination the recessive gene. This scenario is called a bottleneck effect, and it is typical of evolutionary process that takes place when a lot of people migrate to form a new population.
A phenotypic bottleneck can also occur when the survivors of a catastrophe such as an outbreak or mass hunting incident are concentrated in an area of a limited size. The remaining individuals will be mostly homozygous for the dominant allele meaning that they all share the same phenotype and thus share the same fitness characteristics. This situation could be caused by war, earthquakes, or even plagues. Whatever the reason the genetically distinct population that is left might be prone to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a deviation from the expected values due to differences in fitness. They give the famous example of twins who are both genetically identical and share the same phenotype, but one is struck by lightning and dies, but the other lives to reproduce.
에볼루션 슬롯 of drift can be crucial in the evolution of an entire species. It's not the only method for evolution. The main alternative is a process called natural selection, in which phenotypic variation in an individual is maintained through mutation and migration.
Stephens argues that there is a major difference between treating drift as a force or an underlying cause, and considering other causes of evolution, such as mutation, selection and migration as forces or causes. He claims that a causal-process account of drift allows us separate it from other forces, and this distinction is essential. He further argues that drift is a directional force: that is it tends to reduce heterozygosity, and that it also has a specific magnitude that is determined by the size of the population.
Evolution through Lamarckism
In high school, students study biology, they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is often known as "Lamarckism" and it states that simple organisms develop into more complex organisms by the inheritance of traits which result from the organism's natural actions use and misuse. Lamarckism can be demonstrated by the giraffe's neck being extended to reach higher branches in the trees. This causes giraffes' longer necks to be passed to their offspring, who would then grow even taller.
Lamarck was a French Zoologist. In his inaugural lecture for his course on invertebrate zoology at the Museum of Natural History in Paris on the 17th May 1802, he introduced an original idea that fundamentally challenged the conventional wisdom about organic transformation. According to him living things evolved from inanimate matter via the gradual progression of events. Lamarck wasn't the first to make this claim but he was regarded as the first to offer the subject a thorough and general explanation.
The most popular story is that Charles Darwin's theory on evolution by natural selection and Lamarckism were competing in the 19th century. Darwinism eventually triumphed and led to the creation of what biologists today call the Modern Synthesis. The Modern Synthesis theory denies the possibility that acquired traits can be inherited and instead suggests that organisms evolve by the symbiosis 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 idea was never a key element of any of their evolutionary theories. This is partly because it was never tested scientifically.
It's been more than 200 year since Lamarck's birth and in the field of genomics there is a growing evidence base that supports the heritability acquired characteristics. This is also known as "neo Lamarckism", or more often epigenetic inheritance. It is a variant of evolution that is just as valid as the more popular neo-Darwinian model.
Evolution by adaptation
One of the most common misconceptions about evolution is that it is a result of a kind of struggle to survive. This is a false assumption and overlooks other forces that drive evolution. The fight for survival can be better described as a struggle to survive in a particular environment. This may include not only other organisms as well as the physical surroundings themselves.
To understand how evolution works, it is helpful to understand what is adaptation. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce within its environment. It could be a physiological structure such as fur or feathers, or a behavioral trait like moving into shade in hot weather or stepping out at night to avoid the cold.
The ability of a living thing to extract energy from its surroundings and interact with other organisms as well as their physical environments is essential to its survival. The organism must possess the right genes to create offspring, and it should be able to locate enough food and other resources. The organism should also be able reproduce itself at the rate that is suitable for its particular niche.
These factors, in conjunction with gene flow and mutations, can lead to a shift in the proportion of different alleles in the gene pool of a population. This shift in the frequency of alleles can result in the emergence of new traits and eventually new species over time.
Many of the characteristics we admire in animals and plants are adaptations, such as lungs or gills to extract oxygen from the air, feathers or fur to provide insulation, long legs for running away from predators and camouflage for hiding. However, a proper understanding of adaptation requires attention to the distinction between the physiological and behavioral characteristics.
Physiological adaptations like thick fur or gills, are physical characteristics, whereas behavioral adaptations, such as the tendency to search for companions or to retreat to the shade during hot weather, aren't. It is also important to remember that a insufficient planning does not make an adaptation. Inability to think about the consequences of a decision, even if it appears to be logical, can make it inflexible.