The Importance of Understanding Evolution
The majority of evidence that supports evolution comes from observing organisms in their natural environment. Scientists use laboratory experiments to test evolution theories.
As time passes the frequency of positive changes, including those that help an individual in his struggle to survive, grows. This is known as natural selection.
Natural Selection
Natural selection theory is a central concept in evolutionary biology. It is also a crucial topic for science education. Numerous studies suggest that the concept and its implications are poorly understood, especially for young people, and even those with postsecondary biological education. A basic understanding of the theory however, is essential for both practical and academic settings such as research in the field of medicine or management of natural resources.
Natural selection can be understood as a process which favors beneficial traits and makes them more prominent in a group. This improves their fitness value. This fitness value is determined by the contribution of each gene pool to offspring in each generation.
Despite its ubiquity, this theory is not without its critics. They argue that it's implausible that beneficial mutations are constantly more prevalent in the gene pool. They also argue that random genetic drift, environmental pressures and other factors can make it difficult for beneficial mutations within a population to gain a place in the population.
These criticisms are often grounded in the notion that natural selection is an argument that is circular. A trait that is beneficial must to exist before it can be beneficial to the population, and it will only be maintained in populations if it is beneficial. The opponents of this view argue that the concept of natural selection isn't an actual scientific argument instead, it is an assertion about the effects of evolution.
A more sophisticated criticism of the theory of natural selection focuses on its ability to explain the evolution of adaptive traits. These characteristics, referred to as adaptive alleles are defined as those that increase the success of a species' reproductive efforts in the presence of competing alleles. The theory of adaptive genes is based on three components that are believed to be responsible for the creation of these alleles by natural selection:
The first element is a process called genetic drift, which occurs when a population is subject to random changes to its genes. This can result in a growing or shrinking population, depending on how much variation there is in the genes. The second part is a process known as competitive exclusion, which explains the tendency of certain alleles to be removed from a population due to competition with other alleles for resources like food or mates.
Genetic Modification
Genetic modification is a term that refers to a range of biotechnological techniques that can alter the DNA of an organism. This can result in a number of benefits, including increased resistance to pests and improved nutritional content in crops. It can also be used to create medicines and gene therapies which correct the genes responsible for diseases. Genetic Modification is a valuable tool for tackling many of the world's most pressing problems like the effects of climate change and hunger.
Scientists have traditionally used models such as mice or flies to study the function of certain genes. This method is limited by the fact that the genomes of organisms cannot be modified to mimic natural evolutionary processes. Scientists are now able to alter DNA directly with gene editing tools like CRISPR-Cas9.
This is known as directed evolution. In essence, scientists determine the target gene they wish to alter and then use an editing tool to make the necessary change. Then, they insert the modified genes into the body and hope that it will be passed on to the next generations.
One problem with this is that a new gene inserted into an organism can result in unintended evolutionary changes that undermine the intended purpose of the change. For example, a transgene inserted into the DNA of an organism may eventually compromise its fitness in the natural environment and consequently be eliminated by selection.
Another concern is ensuring that the desired genetic modification is able to be absorbed into all organism's cells. This is a major hurdle since each type of cell in an organism is distinct. For example, cells that make up the organs of a person are very different from the cells which make up the reproductive tissues. To make a major distinction, you must focus on all cells.
These issues have led some to question the ethics of the technology. Some people believe that playing with DNA crosses moral boundaries and is similar to playing God. Others are concerned that Genetic Modification will lead to unanticipated consequences that could adversely affect the environment or human health.
Adaptation
The process of adaptation occurs when genetic traits change to better suit the environment in which an organism lives. These changes are typically the result of natural selection that has taken place over several generations, but they may also be caused by random mutations which make certain genes more common in a population. Adaptations are beneficial for the species or individual and may help it thrive in its surroundings. Finch beak shapes on Galapagos Islands, and thick fur on polar bears are examples of adaptations. In certain instances, two species may evolve to be dependent on each other in order to survive. Orchids, for instance have evolved to mimic the appearance and smell of bees to attract pollinators.
An important factor in free evolution is the role of competition. The ecological response to an environmental change is less when competing species are present. This is due to the fact that interspecific competition asymmetrically affects the size of populations and fitness gradients. This in turn influences the way the evolutionary responses evolve after an environmental change.
The form of resource and competition landscapes can also have a strong impact on the adaptive dynamics. For instance an elongated or bimodal shape of the fitness landscape may increase the likelihood of character displacement. Also, a low availability of resources could increase the probability of interspecific competition by reducing the size of the equilibrium population for various phenotypes.
In simulations using different values for the variables k, m v and n I found that the highest adaptive rates of the disfavored species in a two-species alliance are significantly slower than the single-species scenario. This is because the favored species exerts direct and indirect competitive pressure on the one that is not so which decreases its population size and causes it to fall behind the maximum moving speed (see the figure. 3F).
As the u-value approaches zero, the effect of different species' adaptation rates becomes stronger. At this point, the preferred species will be able to attain its fitness peak more quickly than the disfavored species, even with a large u-value. The species that is preferred will therefore exploit the environment faster than the disfavored species and the evolutionary gap will grow.
Evolutionary Theory
As one of the most widely accepted scientific theories evolution is an integral aspect of how biologists examine living things. It's based on the concept that all biological species have evolved from common ancestors by natural selection. According to BioMed Central, this is the process by which the trait or gene that allows an organism to survive and reproduce in its environment becomes more common within the population. The more often a gene is transferred, the greater its prevalence and the probability of it creating an entirely new species increases.
The theory also explains why certain traits become more prevalent in the population due to a phenomenon known as "survival-of-the fittest." Basically, those with genetic traits that give them an advantage over their competition have a higher likelihood of surviving and generating offspring. The offspring of these will inherit the advantageous genes and over time the population will slowly grow.
In the years following Darwin's death evolutionary biologists led by theodosius Dobzhansky, Julian Huxley (the grandson of Darwin's bulldog Thomas Huxley), Ernst Mayr and George Gaylord Simpson further extended his theories. This group of biologists known as the Modern Synthesis, produced an evolutionary model that was taught to millions of students during the 1940s and 1950s.
The model of evolution however, is unable to answer many of the most urgent questions about evolution. It doesn't provide an explanation for, for instance the reason that certain species appear unaltered, while others undergo dramatic changes in a short time. It doesn't address entropy either, which states that open systems tend towards disintegration over time.
The Modern Synthesis is also being challenged by an increasing number of scientists who are concerned that it does not completely explain evolution. In response, various other evolutionary theories have been proposed. This includes the notion that evolution, rather than being a random and predictable process, is driven by "the need to adapt" to a constantly changing environment. It also includes the possibility of soft mechanisms of heredity which do not depend on DNA.