Why Free Evolution Is More Dangerous Than You Thought

What is Free Evolution?

Free evolution is the concept that natural processes can cause organisms to develop over time. This includes the emergence and development of new species.

Many examples have been given of this, such as different varieties of stickleback fish that can live in salt or fresh water, as well as walking stick insect varieties that prefer specific host plants. These reversible traits are not able to explain fundamental changes to basic body plans.

Evolution through Natural Selection

The development of the myriad of living organisms on Earth is a mystery that has intrigued scientists for many centuries. The most widely accepted explanation is Darwin's natural selection process, an evolutionary process that occurs when better-adapted individuals survive and reproduce more successfully than those less well adapted. As time passes, a group of well adapted individuals grows and eventually creates a new species.

Natural selection is a cyclical process that is characterized by the interaction of three elements that are inheritance, variation and reproduction. Sexual reproduction and mutations increase the genetic diversity of an animal species. Inheritance refers to the transmission of a person’s genetic characteristics, which includes recessive and dominant genes, to their offspring. Reproduction is the production of fertile, viable offspring which includes both sexual and asexual methods.

에볼루션 of these elements have to be in equilibrium for natural selection to occur. For instance, if the dominant allele of one gene causes an organism to survive and reproduce more often than the recessive allele, the dominant allele will become more common within the population. If the allele confers a negative survival advantage or lowers the fertility of the population, it will disappear. This process is self-reinforcing meaning that a species with a beneficial characteristic is more likely to survive and reproduce than one with an inadaptive trait. The more fit an organism is which is measured by its ability to reproduce and survive, is the more offspring it can produce. Individuals with favorable characteristics, such as the long neck of giraffes, or bright white patterns on male peacocks are more likely to others to reproduce and survive which eventually leads to them becoming the majority.

Natural selection only affects populations, not on individuals. This is a major distinction from the Lamarckian evolution theory which holds that animals acquire traits due to use or lack of use. If a giraffe expands its neck in order to catch prey, and the neck becomes longer, then its offspring will inherit this trait. The differences in neck length between generations will continue until the giraffe's neck gets too long to no longer breed with other giraffes.

Evolution through Genetic Drift

In genetic drift, alleles at a gene may reach different frequencies in a population through random events. Eventually, only one will be fixed (become common enough to no more be eliminated through natural selection), and the other alleles drop in frequency. In the extreme this, it leads to a single allele dominance. The other alleles are basically eliminated and heterozygosity has diminished to zero. In a small number of people it could result in the complete elimination of recessive gene. This is known as the bottleneck effect and is typical of the evolutionary process that occurs when the number of individuals migrate to form a group.

A phenotypic bottleneck could occur when the survivors of a disaster like an epidemic or mass hunting event, are concentrated into a small area. The survivors will share a dominant allele and thus will share the same phenotype. This may be caused by war, earthquake or even a disease. Regardless of the cause, the genetically distinct population that remains is susceptible to genetic drift.

Walsh, Lewens and Ariew define drift as a deviation from the expected values due to differences in fitness. They cite the famous example of twins who are both genetically identical and have exactly the same phenotype. However one is struck by lightning and dies, whereas the other continues to reproduce.

This kind of drift could play a significant part in the evolution of an organism. It is not the only method for evolution. The most common alternative is a process known as natural selection, where the phenotypic variation of an individual is maintained through mutation and migration.

Stephens claims that there is a significant distinction between treating drift as a force or an underlying cause, and treating other causes of evolution like mutation, selection and migration as causes or causes. He argues that a causal-process explanation of drift lets us distinguish it from other forces, and this differentiation is crucial. He also argues that drift has a direction: that is it tends to eliminate heterozygosity. It also has a magnitude, that is determined by population size.

Evolution by Lamarckism

Biology students in high school are frequently introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution is often called "Lamarckism" and it states that simple organisms develop into more complex organisms through the inheritance of characteristics which result from an organism's natural activities use and misuse. Lamarckism can be illustrated by an giraffe's neck stretching to reach higher levels of leaves in the trees. This could result in giraffes passing on their longer necks to their offspring, who would then get taller.

Lamarck Lamarck, a French Zoologist from France, presented an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged previous thinking on organic transformation. In his view living things evolved from inanimate matter through an escalating series of steps. Lamarck was not the first to make this claim but he was thought of as the first to offer the subject a comprehensive and general explanation.

The most popular story is that Lamarckism grew into an opponent to Charles Darwin's theory of evolutionary natural selection, and that the two theories fought it out in the 19th century. Darwinism ultimately prevailed and led to what biologists call the Modern Synthesis. The theory argues that traits acquired through evolution can be inherited, and instead, it argues that organisms develop by the symbiosis of environmental factors, such as natural selection.

Lamarck and his contemporaries supported the idea that acquired characters could be passed on to the next generation. However, this concept was never a major part of any of their evolutionary theories. This is partly because it was never scientifically validated.

But it is now more than 200 years since Lamarck was born and in the age of genomics, there is a large amount of evidence that supports the possibility of inheritance of acquired traits. This is often called "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 through the process of adaptation

One of the most common misconceptions about evolution is that it is driven by a type of struggle to survive. In fact, this view is a misrepresentation of natural selection and ignores the other forces that determine the rate of evolution. The struggle for survival is more accurately described as a struggle to survive in a specific environment, which can be a struggle that involves not only other organisms, but as well the physical environment.

To understand how evolution works it is beneficial to consider what adaptation is. Adaptation is any feature that allows a living thing to survive in its environment and reproduce. It could be a physical structure such as feathers or fur. Or it can be a behavior trait, like moving into the shade during the heat, or moving out to avoid the cold at night.

The survival of an organism is dependent on its ability to extract energy from the environment and interact with other organisms and their physical environments. The organism must possess the right genes to produce offspring, and be able to find enough food and resources. In addition, the organism should be able to reproduce itself at a high rate within its niche.

These elements, in conjunction with mutation and gene flow, lead to a change in the proportion of alleles (different varieties of a particular gene) in a population's gene pool. As time passes, this shift in allele frequencies could result in the emergence of new traits and eventually new species.

A lot of the traits we admire in animals and plants are adaptations, for example, lungs or gills to extract oxygen from the air, fur or feathers for insulation and long legs for running away from predators, and camouflage for hiding. To comprehend adaptation it is essential to distinguish between behavioral and physiological traits.

Physical traits such as the thick fur and gills are physical traits. The behavioral adaptations aren't an exception, for instance, the tendency of animals to seek companionship or to retreat into the shade in hot weather. In addition, it is important to note that lack of planning does not mean that something is an adaptation. Inability to think about the implications of a choice even if it appears to be rational, could make it unadaptive.

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Pub: 23 Dec 2024 10:56 UTC
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