What is Free Evolution?
Free evolution is the notion that natural processes can cause organisms to develop over time. This includes the emergence and development of new species.
This is evident in many examples such as the stickleback fish species that can be found in fresh or saltwater and walking stick insect species that are apprehensive about specific host plants. These typically reversible traits do not explain the fundamental changes in the basic body plan.
Evolution by Natural Selection
Scientists have been fascinated by the development of all living organisms that inhabit our planet for centuries. Charles Darwin's natural selection theory is the best-established explanation. This process occurs when those who are better adapted have more success in reproduction and survival than those who are less well-adapted. Over time, a population of well-adapted individuals expands and eventually becomes a new species.
Natural selection is an ongoing process and involves the interaction of three factors: variation, reproduction and inheritance. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity within an animal species. Inheritance refers to the passing of a person's genetic traits to their offspring that includes dominant and recessive alleles. Reproduction is the process of creating viable, fertile offspring. This can be done by both asexual or sexual methods.
All of these factors have to be in equilibrium for natural selection to occur. For example when the dominant allele of the gene allows an organism to live and reproduce more often than the recessive allele the dominant allele will become more prominent in the population. If the allele confers a negative survival advantage 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 characteristic will live and reproduce more quickly than those with a maladaptive feature. The more fit an organism is, measured by its ability reproduce and endure, is the higher number of offspring it will produce. People with desirable characteristics, like having a longer neck in giraffes or bright white colors in male peacocks are more likely to be able to survive and create offspring, which means they will eventually make up the majority of the population over time.
Natural selection is only an aspect of populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution which states that animals acquire characteristics through use or neglect. For instance, if the Giraffe's neck grows longer due to stretching to reach for prey and its offspring will inherit a more long neck. The length difference between generations will persist until the giraffe's neck becomes too long that it can not breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, alleles at a gene may reach different frequencies in a group by chance events. In the end, only one will be fixed (become common enough that it can no longer be eliminated by natural selection) and the rest of the alleles will diminish in frequency. This can lead to an allele that is dominant at the extreme. Other alleles have been essentially eliminated and heterozygosity has decreased to zero. In a small population it could result in the complete elimination the recessive gene. This scenario is called a bottleneck effect, and it is typical of the kind of evolutionary process that occurs when a large number of individuals migrate to form a new group.
A phenotypic bottleneck may also occur when the survivors of a catastrophe such as an outbreak or a mass hunting event are concentrated in an area of a limited size. The survivors will carry an allele that is dominant and will share the same phenotype. This can be caused by war, earthquakes or even a plague. Whatever the reason the genetically distinct population that remains could be prone to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected values due to differences in fitness. They give a famous example of twins that are genetically identical, have identical phenotypes but one is struck by lightning and dies, while the other lives and reproduces.
This type of drift is very important in the evolution of the species. However, it is not the only method to progress. The most common alternative is a process called natural selection, where the phenotypic variation of the population is maintained through mutation and migration.
Stephens argues that there is a big distinction between treating 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 permits us to differentiate it from the other forces, and that this distinction is crucial. He further argues that drift has a direction: that is, it tends to eliminate heterozygosity, and that it also has a size, that is determined by population size.
에볼루션바카라 through Lamarckism
Biology students in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, often referred to as “Lamarckism” is based on the idea that simple organisms transform into more complex organisms adopting traits that result from the organism's use and misuse. Lamarckism can be demonstrated by an giraffe's neck stretching to reach higher levels of leaves in the trees. This could cause giraffes' longer necks to be passed on to their offspring who would then become taller.
Lamarck was a French zoologist and, 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 innovative concept that completely challenged the conventional wisdom about organic transformation. According to Lamarck, living things evolved from inanimate material through a series gradual steps. Lamarck was not the first to suggest that this might be the case, but his reputation is widely regarded as giving the subject its first broad and thorough treatment.
The predominant story is that Charles Darwin's theory of natural selection and Lamarckism were rivals in the 19th century. Darwinism ultimately won which led to what biologists refer to as the Modern Synthesis. click through the following post argues that acquired traits can be passed down through generations and instead argues that organisms evolve through the selective action of environment factors, such as Natural Selection.
While Lamarck supported the notion of inheritance through acquired characters and his contemporaries also paid lip-service to this notion however, it was not a central element in any of their evolutionary theories. This is partly because it was never tested scientifically.
It's been more than 200 years since Lamarck was born and, in the age of genomics there is a huge amount of evidence to support the heritability of acquired traits. This is also known as "neo Lamarckism", or more commonly epigenetic inheritance. This is a version that is just as valid as the popular Neodarwinian model.
Evolution by adaptation
One of the most popular 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 precisely described as a fight to survive within a specific environment, which can involve not only other organisms but as well the physical environment.
Understanding adaptation is important to understand evolution. The term "adaptation" refers to any characteristic that allows a living organism to live in its environment and reproduce. It could be a physical structure such as feathers or fur. It could also be a characteristic of behavior that allows you to move to the shade during hot weather, or escaping the cold at night.
The capacity of a living thing to extract energy from its surroundings and interact with other organisms as well as their physical environments, is crucial to its survival. The organism needs to have the right genes to produce offspring, and it should be able to access enough food and other resources. The organism must be able to reproduce at a rate that is optimal for its particular niche.
These factors, together with mutation and gene flow result in a change in the proportion of alleles (different types of a gene) 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.
A lot of the traits we admire in animals and plants are adaptations, like lung or gills for removing oxygen from the air, feathers or fur to protect themselves, long legs for running away from predators, and camouflage to hide. To comprehend adaptation, it is important to discern between physiological and behavioral characteristics.
Physiological adaptations, like the thick fur or gills are physical traits, whereas behavioral adaptations, such as the tendency to seek out companions or to retreat into the shade in hot weather, aren't. It is important to keep in mind that lack of planning does not result in an adaptation. In fact, failing to consider the consequences of a choice can render it unadaptive even though it appears to be sensible or even necessary.