What is Free Evolution?
Free evolution is the concept that the natural processes that organisms go through can lead them to evolve over time. This includes the creation of new species as well as the change in appearance of existing species.
This is evident in numerous examples such as the stickleback fish species that can be found in fresh or saltwater and walking stick insect types that have a preference for particular host plants. These mostly reversible trait permutations however, are not able to explain fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all living creatures that inhabit our planet for ages. The most well-known explanation is that of Charles Darwin's natural selection process, an evolutionary process that is triggered when more well-adapted individuals live longer and reproduce more successfully than those less well adapted. As time passes, the number of well-adapted individuals grows and eventually forms an entirely new species.
Natural selection is a cyclical process that is characterized by the interaction of three elements: variation, inheritance and reproduction. Variation is caused by mutation and sexual reproduction, both of which increase the genetic diversity of a species. Inheritance is the term used to describe the transmission of genetic traits, which include both dominant and recessive genes to their offspring. Reproduction is the process of creating fertile, viable offspring. This can be done by both asexual or sexual methods.
All of these elements must be in balance for natural selection to occur. If, for instance, a dominant gene allele causes an organism reproduce and live longer than the recessive gene allele, then the dominant allele will become more common in a population. But if the allele confers an unfavorable survival advantage or reduces fertility, it will disappear from the population. The process is self-reinforcing meaning that an organism that has an adaptive trait will live and reproduce more quickly than those with a maladaptive feature. The greater an organism's fitness, measured by its ability reproduce and survive, is the more offspring it will produce. People with desirable traits, such as longer necks in giraffes, or bright white color patterns in male peacocks are more likely survive and have offspring, which means they will make up the majority of the population over time.
Natural selection is only an element in the population and not on individuals. This is a major distinction from the Lamarckian theory of evolution which argues that animals acquire traits through use or disuse. For example, if a animal's neck is lengthened by stretching to reach prey, its offspring will inherit a longer neck. The length difference between generations will continue until the giraffe's neck gets so long that it can not breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles of the same gene are randomly distributed within a population. Eventually, only one 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 can result in dominance in extreme. The other alleles are virtually eliminated and heterozygosity diminished to zero. In a small population, this could lead to the total elimination of recessive allele. This is known as a bottleneck effect and it is typical of evolutionary process that takes place when a large number of individuals migrate to form a new group.
A phenotypic bottleneck could happen when the survivors of a catastrophe, such as an epidemic or a mass hunting event, are condensed into a small area. The remaining individuals are likely to be homozygous for the dominant allele, meaning that they all have the same phenotype and thus have the same fitness traits. This can be caused by earthquakes, war or even a plague. The genetically distinct population, if it is left susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew employ Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from expected values for different fitness levels. They give a famous instance of twins who are genetically identical, share identical phenotypes but one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift can be vital to the evolution of an entire species. It is not the only method of evolution. The most common alternative is to use a process known as natural selection, in which phenotypic variation in an individual is maintained through mutation and migration.
Stephens argues there is a huge difference between treating drift like a force or cause, and considering other causes, such as migration and selection as causes and forces. Stephens claims that a causal mechanism account of drift allows us to distinguish it from these other forces, and that this distinction is essential. He also argues that drift has a direction: that is it tends to eliminate heterozygosity. It also has a size, that is determined by population size.
Evolution through Lamarckism
Biology students in high school are often introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, also called "Lamarckism which means that simple organisms transform into more complex organisms inheriting characteristics that are a product of the organism's use and misuse. Lamarckism is illustrated through a giraffe extending its neck to reach higher branches in the trees. This would cause the necks of giraffes that are longer to be passed on to their offspring who would then become taller.
Lamarck was a French zoologist and, in his lecture to begin his course on invertebrate zoology at the Museum of Natural History in Paris on the 17th May 1802, he presented an original idea that fundamentally challenged previous thinking about organic transformation. According Lamarck, living organisms evolved from inanimate material through a series of gradual steps. Lamarck wasn't the first to make this claim, but he was widely considered to be the first to offer the subject a thorough and general explanation.
The popular narrative is that Lamarckism grew into a rival to Charles Darwin's theory of evolution by natural selection, and that the two theories battled it out in the 19th century. Darwinism eventually triumphed and led to the creation of what biologists today call the Modern Synthesis. The theory argues the possibility that acquired traits can be inherited and instead argues that organisms evolve through the action of environmental factors, including natural selection.
Lamarck and his contemporaries believed in the notion that acquired characters could be passed down to future generations. However, this notion was never a key element of any of their theories on evolution. This is largely due to the fact that it was never validated scientifically.
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 to support the heritability of acquired characteristics. weblink is also known as "neo Lamarckism", or more generally epigenetic inheritance. This is a variant that is as reliable as the popular Neodarwinian model.
Evolution through adaptation
One of the most popular misconceptions about evolution is its being driven by a fight for survival. This notion is not true and ignores other forces driving evolution. The fight for survival can be more effectively described as a struggle to survive within a particular environment, which may be a struggle that involves not only other organisms, but as well the physical environment.
To understand how evolution operates it is important to think about what adaptation is. The term "adaptation" refers to any characteristic that allows a living thing to live in its environment and reproduce. It could be a physiological structure, such as feathers or fur, or a behavioral trait like moving to the shade during the heat or leaving at night to avoid the cold.
An organism's survival depends on its ability to obtain energy from the environment and interact with other living organisms and their physical surroundings. The organism needs to have the right genes to generate offspring, and must be able to find enough food and other resources. The organism should also be able to reproduce itself at a rate that is optimal for its particular niche.
These elements, in conjunction with gene flow and mutation result in a change in the proportion of alleles (different forms of a gene) in the gene pool of a population. 에볼루션 바카라 무료 in allele frequency can lead to the emergence of new traits and eventually new species in the course of time.
Many of the features we admire in animals and plants are adaptations. For instance lung or gills that extract oxygen from the air, fur and feathers as insulation long legs to run away from predators, and camouflage to hide. However, a proper understanding of adaptation requires attention to the distinction between physiological and behavioral characteristics.
Physiological adaptations, like thick fur or gills are physical traits, whereas behavioral adaptations, like the desire to find companions or to move into the shade in hot weather, are not. In addition it is important to note that a lack of thought is not a reason to make something an adaptation. A failure to consider the consequences of a decision even if it seems to be logical, can make it inflexible.