What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to evolve over time. This includes the creation of new species and alteration of the appearance of existing species.
A variety of examples have been provided of this, including various varieties of fish called sticklebacks that can live in fresh or salt water and walking stick insect varieties that prefer specific host plants. These typically reversible traits do not explain the fundamental changes in the basic body plan.
Evolution through Natural Selection
Scientists have been fascinated by the development of all the living creatures that inhabit our planet for many centuries. The most well-known explanation is Charles Darwin's natural selection, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more successfully than those less well adapted. Over time, the population of well-adapted individuals becomes larger and eventually creates an entirely new species.
Natural selection is an ongoing process and involves the interaction of three factors including reproduction, variation and inheritance. Sexual reproduction and mutation increase genetic diversity in an animal species. Inheritance refers to the transmission of genetic traits, including recessive and dominant genes to their offspring. Reproduction is the process of producing viable, fertile offspring. This can be accomplished through sexual or asexual methods.
Natural selection can only occur when all of these factors are in balance. If, for instance, a dominant gene allele allows an organism to reproduce and live longer than the recessive gene The dominant allele is more prevalent in a group. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will go away. The process is self-reinforcing, which means that an organism that has an adaptive trait will survive and reproduce much more than those with a maladaptive feature. The higher the level of fitness an organism has as measured by its capacity to reproduce and endure, is the higher number of offspring it will produce. People with good traits, like a long neck in Giraffes, or the bright white 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 argues that animals acquire characteristics through use or neglect. For instance, if the animal's neck is lengthened by stretching to reach for prey its offspring will inherit a more long neck. The differences in neck size between generations will continue to increase until the giraffe becomes unable to breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, the alleles within a gene can attain different frequencies in a group by chance events. Eventually, one of them will reach fixation (become so widespread that it is unable to be removed by natural selection) and other alleles fall to lower frequency. This could lead to a dominant allele at the extreme. The other alleles are eliminated, and heterozygosity is reduced to zero. In a small number of people it could lead to the complete elimination of recessive alleles. This scenario is called the bottleneck effect and is typical of the evolution process that occurs when the number of individuals migrate to form a group.
A phenotypic 'bottleneck' can also occur when the survivors of a catastrophe such as an outbreak or a mass hunting event are confined to the same area. The surviving individuals will be largely homozygous for the dominant allele, meaning that they all have the same phenotype, and therefore have the same fitness characteristics. This could be caused by earthquakes, war or even a plague. The genetically distinct population, if left susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from the expected values due to differences in fitness. They give a famous example of twins that are genetically identical, share the exact same phenotype and yet one is struck by lightning and dies, while the other lives and reproduces.
This type of drift is very important in the evolution of a species. It is not the only method of evolution. The primary alternative is a process called natural selection, where the phenotypic diversity of the population is maintained through mutation and migration.
Stephens asserts that there is a huge difference between treating drift like a force or cause, and treating other causes like migration and selection as causes and forces. He argues that a causal-process model of drift allows us to separate it from other forces and that 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, that is determined by the size of the population.
Evolution by Lamarckism
Students of biology in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, also referred to as “Lamarckism” is based on the idea that simple organisms transform into more complex organisms by inheriting characteristics that are a product of an organism's use and disuse. Lamarckism is typically illustrated by an image of a giraffe that extends its neck longer to reach leaves higher up in the trees. This would cause the necks of giraffes that are longer to be passed onto their offspring who would grow taller.
Lamarck the French Zoologist from France, presented an innovative idea in his opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. In his opinion living things had evolved from inanimate matter through an escalating series of steps. Lamarck was not the first to suggest that this could be the case but his reputation is widely regarded as having given 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 out in the 19th century. Darwinism eventually prevailed, leading to what biologists call the Modern Synthesis. This theory denies acquired characteristics are passed down from generation to generation and instead, it claims that organisms evolve through the influence of environment elements, like Natural Selection.
Lamarck and his contemporaries endorsed the idea that acquired characters could be passed down to future generations. However, this idea was never a major part of any of their theories on evolution. This is partly because it was never scientifically tested.
But 무료 에볼루션 is now more than 200 years since Lamarck was born and in the age genomics there is a huge amount of evidence to support the heritability of acquired characteristics. This is often referred to as "neo-Lamarckism" or more commonly epigenetic inheritance. This is a model that is as valid as the popular Neodarwinian model.
Evolution by the process of adaptation
One of the most common 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 are driving evolution. The fight for survival is better described as a fight to survive in a particular environment. This may include not just other organisms but also the physical environment itself.
Understanding the concept of adaptation is crucial to comprehend evolution. It is a feature that allows a living thing to live in its environment and reproduce. It can be a physiological structure, such as feathers or fur or a behavioral characteristic such as a tendency to move to the shade during hot weather or coming out at night to avoid the cold.
The ability of an organism to draw energy from its surroundings and interact with other organisms as well as their physical environments is essential to its survival. The organism must have the right genes for producing offspring, and be able to find enough food and resources. The organism should also be able reproduce itself at an amount that is appropriate for its specific niche.
These elements, in conjunction with gene flow and mutation result in changes in the ratio of alleles (different varieties of a particular gene) in the population's gene pool. This shift in the frequency of alleles can lead to the emergence of new traits, and eventually new species over time.
Many of the characteristics we admire about animals and plants are adaptations, such as lungs or gills to extract oxygen from the air, feathers or fur to protect themselves long legs to run away from predators and camouflage to hide. To understand the concept of adaptation it is essential to differentiate between physiological and behavioral traits.
Physical traits such as large gills and thick fur are physical traits. Behavioral adaptations are not, such as the tendency of animals to seek out companionship or to retreat into the shade during hot temperatures. It is important to keep in mind that lack of planning does not make an adaptation. A failure to consider the implications of a choice even if it seems to be rational, could make it inflexible.