What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to evolve over time. This includes the appearance and growth of new 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 varieties that are apprehensive about specific host plants. These reversible traits cannot explain fundamental changes to basic body plans.
Evolution by Natural Selection
The development of the myriad of living creatures on Earth is an enigma that has intrigued scientists for decades. The best-established explanation is Darwin's natural selection process, a process that is triggered when more well-adapted individuals live longer and reproduce more successfully than those less well adapted. As time passes, a group of well-adapted individuals expands and eventually forms a whole new species.
Natural selection is an ongoing process and involves the interaction of three factors that are: reproduction, variation and inheritance. Sexual reproduction and mutation increase the genetic diversity of the species. Inheritance refers to the transmission of a person’s genetic traits, which include recessive and dominant genes, to their offspring. Reproduction is the production of fertile, viable offspring, which includes both asexual and sexual methods.
Natural selection only occurs when all the factors are in harmony. If, for instance an allele of a dominant gene causes an organism reproduce and live longer than the recessive allele, then the dominant allele will become more prevalent in a population. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will be eliminated. The process is self-reinforced, meaning that a species that has a beneficial trait is more likely to survive and reproduce than one with a maladaptive trait. The more offspring that an organism has the better its fitness that is determined by its capacity to reproduce itself and survive. Individuals with favorable traits, such as having a longer neck in giraffes and bright white color patterns in male peacocks are more likely to be able to survive and create offspring, and thus will become the majority of the population over time.
Natural selection only affects populations, not on individuals. This is an important distinction from the Lamarckian theory of evolution, which claims that animals acquire characteristics through use or disuse. If a giraffe stretches its neck to catch prey and the neck grows longer, then its children will inherit this characteristic. The difference in neck length between generations will continue until the giraffe's neck becomes too long to no longer breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, alleles at a gene may be at different frequencies in a group through random events. In the end, one will reach fixation (become so widespread that it cannot be removed through natural selection), while other alleles will fall to lower frequency. This could lead to dominance at the extreme. The other alleles are eliminated, and heterozygosity decreases to zero. In a small group this could lead to the complete elimination of the recessive gene. This is known as the bottleneck effect and is typical of an evolutionary process that occurs whenever an enormous number of individuals move to form a group.
A phenotypic bottleneck may occur when survivors of a disaster, such as an epidemic or a massive hunt, are confined into a small area. The remaining individuals are likely to be homozygous for the dominant allele, which means that they will all have the same phenotype and will therefore have the same fitness traits. This situation could be caused by earthquakes, war or even a plague. The genetically distinct population, if it remains vulnerable to genetic drift.
Walsh, Lewens, and Ariew utilize Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from the expected values for differences in fitness. They provide a well-known instance of twins who are genetically identical and have identical phenotypes but one is struck by lightning and dies, whereas the other lives and reproduces.
This type of drift is crucial in the evolution of an entire species. However, it's not the only method to develop. The primary alternative is a process called natural selection, where the phenotypic variation of the population is maintained through mutation and migration.
Stephens asserts that there is a big difference between treating the phenomenon of drift as a force or an underlying cause, and considering other causes of evolution, such as mutation, selection and migration as forces or causes. Stephens claims that a causal process account of drift permits us to differentiate it from the other forces, and this distinction is crucial. He also argues that drift has direction, i.e., it tends to eliminate heterozygosity. It also has a size, that is determined by population size.
This Internet page through Lamarckism
Biology students in high school are often introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution is commonly called "Lamarckism" and it asserts that simple organisms evolve 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 leaves in the trees. This would result in giraffes passing on their longer necks to their offspring, who would then get taller.
Lamarck Lamarck, a French Zoologist from France, presented a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. According to Lamarck, living creatures evolved from inanimate matter 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 being the one who gave the subject his first comprehensive and thorough treatment.
The most popular story is that Lamarckism became a rival to Charles Darwin's theory of evolution by natural selection and that the two theories battled each other in the 19th century. Darwinism eventually prevailed which led to what biologists refer to as the Modern Synthesis. The theory argues that acquired characteristics can be acquired through inheritance and instead argues that organisms evolve through the action of environmental factors, including natural selection.
While Lamarck endorsed the idea of inheritance through acquired characters and his contemporaries paid lip-service to this notion however, it was not a major feature in any of their evolutionary theorizing. This is largely due to the fact that it was never validated scientifically.
It's been more than 200 year since Lamarck's birth and in the field of genomics, there is an increasing evidence-based body of evidence to support the heritability-acquired characteristics. This is also referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a version that is just as valid as the popular neodarwinian model.
Evolution through adaptation
One of the most common misconceptions about evolution is its being driven by a struggle to survive. This view is inaccurate and ignores other forces driving evolution. The struggle for survival is more precisely described as a fight to survive within a specific environment, which may involve not only other organisms but as well the physical environment.
To understand how evolution operates, it is helpful to think about what adaptation is. It is a feature that allows a living thing to live in its environment and reproduce. It can be a physiological structure like feathers or fur, or a behavioral trait, such as moving into the shade in hot weather or coming out at night to avoid cold.
The ability of an organism to extract energy from its environment 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 create offspring, and must be able to access enough food and other resources. Furthermore, the organism needs to be capable of reproducing itself in a way that is optimally within its environment.
These factors, along with mutation and gene flow, lead to a change in the proportion of alleles (different forms of a gene) in a population's gene pool. Over time, this change in allele frequency can result in the emergence of new traits and eventually new species.
Many of the characteristics we admire about animals and plants are adaptations, like the lungs or gills that extract oxygen from the air, feathers or fur to protect themselves, long legs for running away from predators and camouflage to hide. To understand adaptation it is crucial to discern between physiological and behavioral characteristics.
Physical traits such as thick fur and gills are physical characteristics. Behavioral adaptations are not an exception, for instance, the tendency of animals to seek out companionship or to retreat into the shade during hot temperatures. Furthermore, it is important to remember that lack of planning does not make something an adaptation. click the next web page to consider the effects of a behavior, even if it appears to be logical, can make it inflexible.