Evolution Explained
The most fundamental concept is that all living things alter as they age. These changes may aid the organism in its survival and reproduce or become more adapted to its environment.
Scientists have employed genetics, a new science, to explain how evolution works. They have also used the physical science to determine the amount of energy needed to trigger these changes.
Natural Selection
In order for evolution to occur, organisms need to be able to reproduce and pass their genetic traits on to the next generation. Natural selection is sometimes called "survival for the strongest." However, the term is often misleading, since it implies that only the strongest or fastest organisms will be able to reproduce and survive. In reality, the most adapted organisms are those that are able to best adapt to the conditions in which they live. Environment conditions can change quickly and if a population isn't well-adapted, it will be unable survive, resulting in the population shrinking or disappearing.
Natural selection is the primary element in the process of evolution. This occurs when advantageous traits are more common over time in a population which leads to the development of new species. This process is driven by the genetic variation that is heritable of organisms that results from mutation and sexual reproduction and competition for limited resources.
Selective agents could be any element in the environment that favors or discourages certain traits. These forces could be biological, such as predators, or physical, like temperature. Over time, populations that are exposed to different agents of selection could change in a way that they are no longer able to breed with each other and are considered to be distinct species.
Natural selection is a straightforward concept however, it isn't always easy to grasp. Even among educators and scientists there are a myriad of misconceptions about the process. Surveys have found that students' understanding levels of evolution are only weakly dependent on their levels of acceptance of the theory (see references).
Brandon's definition of selection is restricted to differential reproduction and does not include inheritance. similar site (2011) is one of many authors who have advocated for a more expansive notion of selection, which captures Darwin's entire process. This could explain both adaptation and species.
In addition there are a variety of instances where the presence of a trait increases in a population but does not increase the rate at which individuals with the trait reproduce. These situations are not considered natural selection in the focused sense of the term but could still be in line with Lewontin's requirements for a mechanism to operate, such as when parents with a particular trait produce more offspring than parents without it.
Genetic Variation
Genetic variation refers to the differences between the sequences of the genes of the members of a specific species. Natural selection is among the major forces driving evolution. Mutations or the normal process of DNA restructuring during cell division may result in variations. Different gene variants could result in different traits, such as eye colour fur type, colour of eyes or the capacity to adapt to adverse environmental conditions. If a trait is characterized by an advantage it is more likely to be passed down to the next generation. This is referred to as a selective advantage.
Phenotypic plasticity is a special kind of heritable variant that allows people to alter their appearance and behavior in response to stress or the environment. These changes can enable them to be more resilient in a new environment or make the most of an opportunity, for instance by growing longer fur to guard against cold or changing color to blend in with a specific surface. These phenotypic variations do not alter the genotype, and therefore are not considered to be a factor in the evolution.
Heritable variation is crucial to evolution as it allows adaptation to changing environments. Natural selection can be triggered by heritable variations, since it increases the chance that those with traits that favor the particular environment will replace those who do not. In some cases however the rate of gene variation transmission to the next generation may not be fast enough for natural evolution to keep up.
Many negative traits, like genetic diseases, remain in the population despite being harmful. This is due to a phenomenon known as diminished penetrance. It means that some people who have the disease-associated variant of the gene don't show symptoms or signs of the condition. Other causes include gene-by- environmental interactions as well as non-genetic factors such as lifestyle, diet, and exposure to chemicals.
To understand the reasons why certain undesirable traits are not eliminated by natural selection, it is essential to gain an understanding of how genetic variation influences the process of evolution. Recent studies have revealed that genome-wide association studies focusing on common variants do not capture the full picture of the susceptibility to disease and that a significant percentage of heritability is explained by rare variants. It is imperative to conduct additional studies based on sequencing to identify rare variations across populations worldwide and assess their impact, including the gene-by-environment interaction.
Environmental Changes
While natural selection influences evolution, the environment influences species by altering the conditions within which they live. The famous tale of the peppered moths illustrates this concept: the moths with white bodies, prevalent in urban areas where coal smoke had blackened tree bark were easy targets for predators while their darker-bodied counterparts thrived in these new conditions. However, the reverse is also true--environmental change may alter species' capacity to adapt to the changes they encounter.
Human activities are causing environmental change at a global level and the consequences of these changes are irreversible. These changes are affecting ecosystem function and biodiversity. They also pose serious health risks to the human population especially in low-income nations, due to the pollution of water, air and soil.
For instance an example, the growing use of coal in developing countries like India contributes to climate change, and raises levels of pollution in the air, which can threaten the life expectancy of humans. The world's finite natural resources are being used up at a higher rate by the population of humanity. This increases the risk that many people will suffer from nutritional deficiencies and have no access to safe drinking water.
The impact of human-driven environmental changes on evolutionary outcomes is a tangled mess, with microevolutionary responses to these changes likely to reshape the fitness environment of an organism. These changes can also alter the relationship between a certain characteristic and its environment. For instance, a study by Nomoto and co. that involved transplant experiments along an altitude gradient demonstrated that changes in environmental signals (such as climate) and competition can alter the phenotype of a plant and shift its directional choice away from its previous optimal match.
It is important to understand the ways in which these changes are shaping the microevolutionary patterns of our time, and how we can utilize this information to predict the fates of natural populations in the Anthropocene. This is essential, since the environmental changes being initiated by humans have direct implications for conservation efforts and also for our individual health and survival. It is therefore vital to continue to study the interplay between human-driven environmental changes and evolutionary processes at a worldwide scale.
The Big Bang
There are many theories of the Universe's creation and expansion. None of them is as widely accepted as Big Bang theory. It has become a staple for science classrooms. The theory is the basis for many observed phenomena, like the abundance of light elements, the cosmic microwave back ground radiation and the massive scale structure of the Universe.
The Big Bang Theory is a simple explanation of the way in which the universe was created, 13.8 billions years ago as a massive and unimaginably hot cauldron. Since then, it has grown. This expansion has created everything that is present today, including the Earth and all its inhabitants.
This theory is widely supported by a combination of evidence, including the fact that the universe appears flat to us as well as the kinetic energy and thermal energy of the particles that make up it; the temperature fluctuations in the cosmic microwave background radiation and the relative abundances of light and heavy elements found in the Universe. The Big Bang theory is also well-suited to the data gathered by particle accelerators, astronomical telescopes, and high-energy states.
In the early 20th century, scientists held a minority view on the Big Bang. In 1949 Astronomer Fred Hoyle publicly dismissed it as "a fanciful nonsense." But, following World War II, observational data began to emerge that tipped the scales in favor of the Big Bang. Arno Pennzias, Robert Wilson, and others discovered the cosmic background radiation in 1964. The omnidirectional microwave signal is the result of a time-dependent expansion of the Universe. The discovery of this ionized radioactive radiation, with a spectrum that is in line with a blackbody that is approximately 2.725 K, was a significant turning point for the Big Bang theory and tipped the balance in its favor over the competing Steady State model.
The Big Bang is a major element of the cult television show, "The Big Bang Theory." Sheldon, Leonard, and the rest of the team use this theory in "The Big Bang Theory" to explain a wide range of observations and phenomena. One example is their experiment that will explain how peanut butter and jam are mixed together.