What is Free Evolution?
Free evolution is the notion that the natural processes of organisms can lead to their development over time. This includes the development of new species as well as the alteration of the appearance of existing species.
This has been demonstrated by numerous examples, including stickleback fish varieties that can live in saltwater or fresh water and walking stick insect varieties that prefer particular host plants. These mostly reversible trait permutations however, are not able to be the reason for fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the evolution of all the living creatures that inhabit our planet for many centuries. The best-established explanation is Charles Darwin's natural selection, a process that is triggered when more well-adapted individuals live longer and reproduce more effectively than those who are less well-adapted. Over time, a community of well-adapted individuals expands and eventually creates a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Mutation and sexual reproduction increase genetic diversity in an animal species. Inheritance is the term used to describe the transmission of a person's genetic traits, including both dominant and recessive genes, to their offspring. Reproduction is the process of generating viable, fertile offspring. This can be done via sexual or asexual methods.
Natural selection only occurs when all of these factors are in harmony. If, for example the dominant gene allele allows an organism to reproduce and live longer than the recessive gene allele The dominant allele becomes more prevalent in a group. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will disappear. The process is self-reinforcing, which means that an organism with a beneficial trait will survive and reproduce more than one with an unadaptive trait. The more offspring an organism produces the more fit it is that is determined by its capacity to reproduce itself and survive. Individuals with favorable traits, like a longer neck in giraffes, or bright white color patterns in male peacocks are more likely to survive and produce offspring, so they will become the majority of the population over time.
Natural selection is only a force for populations, not individual organisms. This is a major distinction from the Lamarckian theory of evolution, which states that animals acquire traits through use or disuse. If a giraffe stretches its neck to catch prey, and the neck becomes longer, then its offspring will inherit this characteristic. The length difference between generations will persist until the giraffe's neck gets so long that it can not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles of a gene are randomly distributed in a population. At some point, only one of them will be fixed (become common enough to no longer be eliminated through natural selection) and the rest of the alleles will decrease in frequency. This could lead to dominance in extreme. The other alleles are virtually eliminated and heterozygosity diminished to a minimum. In a small number of people, this could result in the complete elimination the recessive gene. This scenario is called the bottleneck effect and is typical of the evolutionary process that occurs whenever a large number individuals migrate to form a group.
A phenotypic bottleneck can also occur when survivors of a disaster such as an epidemic or mass hunting event, are concentrated into a small area. The survivors will be mostly homozygous for the dominant allele which means they will all have the same phenotype, and consequently have the same fitness traits. This could be caused by a war, earthquake, or even a plague. Regardless of the cause, the genetically distinct population that remains is susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew utilize Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any departure from expected values for differences in fitness. They give the famous example of twins that are genetically identical and share the same phenotype, but one is struck by lightning and dies, whereas the other lives to reproduce.
무료 에볼루션 of drift could play a very important part in the evolution of an organism. However, it's not the only method to evolve. The most common alternative is a process known as natural selection, in which phenotypic variation in the population is maintained through mutation and migration.
Stephens argues that there is a major difference between treating the phenomenon of drift as a force, or an underlying cause, and treating other causes of evolution such as mutation, selection and migration as forces or causes. He argues that a causal process explanation of drift allows us to distinguish it from other forces, and that this distinction is vital. He also argues that drift is a directional force: that is it tends to reduce heterozygosity. He also claims that it also has a magnitude, that is determined by the size of population.
Evolution by Lamarckism
When high school students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, often referred to as “Lamarckism” which means that simple organisms transform into more complex organisms by inheriting characteristics that are a product of the organism's use and misuse. Lamarckism is illustrated through an giraffe's neck stretching to reach higher branches in the trees. This process would cause giraffes to pass on their longer necks to their offspring, who would then grow even taller.
Lamarck, a French zoologist, presented an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. According Lamarck, living organisms evolved from inanimate material through a series of gradual steps. Lamarck was not the only one to suggest that this could be the case, but the general consensus is that he was the one giving the subject its first general and thorough treatment.
The prevailing story is that Lamarckism was a rival to Charles Darwin's theory of evolutionary natural selection and that the two theories fought it out in the 19th century. Darwinism eventually prevailed, leading to what biologists call the Modern Synthesis. This theory denies acquired characteristics can be passed down and instead argues organisms evolve by the selective action of environment elements, like Natural Selection.
While Lamarck believed in the concept 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 theories. This is due to the fact that it was never scientifically validated.
It's been over 200 year since Lamarck's birth and in the field of age genomics, there is a growing body of evidence that supports the heritability of acquired traits. It is sometimes referred to as "neo-Lamarckism" or more commonly, epigenetic inheritance. This is a model that is as reliable as the popular neodarwinian model.
Evolution through adaptation
One of the most common misconceptions about evolution is its being driven by a fight for survival. This is a false assumption and ignores other forces driving evolution. The struggle for survival is more accurately described as a struggle to survive within a particular environment, which can involve not only other organisms but as well the physical environment.
Understanding how adaptation works is essential to understand evolution. It is a feature that allows living organisms to live in its environment and reproduce. It could be a physiological structure such as feathers or fur or a behavioral characteristic like moving to the shade during hot weather or coming out at night to avoid the cold.
The ability of an organism to extract energy from its environment and interact with other organisms, as well as their physical environment, is crucial to its survival. The organism must possess the right genes to generate offspring, and it should be able to locate sufficient food and other resources. In addition, the organism should be able to reproduce itself in a way that is optimally within its environmental niche.
These factors, together with gene flow and mutations, can lead to changes in the proportion of different alleles within a population’s gene pool. As time passes, this shift in allele frequencies could lead to the emergence of new traits, and eventually new species.
Many of the features we appreciate in plants and animals are adaptations. For example, lungs or gills that extract oxygen from air feathers and fur for 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 physiological and behavioral characteristics.
Physiological adaptations like the thick fur or gills are physical characteristics, whereas behavioral adaptations, such as the desire to find friends or to move to the shade during hot weather, are not. Furthermore it is important to remember that lack of planning does not make something an adaptation. Inability to think about the consequences of a decision even if it appears to be logical, can make it unadaptive.