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The Academy's Evolution Site

Biological evolution is one of the most important concepts in biology. The Academies are committed to helping those interested in science to comprehend the evolution theory and how it can be applied across all areas of scientific research.

This site provides a wide range of resources for students, teachers, and general readers on evolution. It contains the most important video clips from NOVA and the WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is used in many religions and cultures as a symbol of unity and love. It also has many practical uses, like providing a framework to understand the evolution of species and how they react to changes in environmental conditions.

The earliest attempts to depict the biological world focused on categorizing organisms into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods, which depend on the collection of various parts of organisms, or fragments of DNA, have significantly increased the diversity of a Tree of Life2. These trees are largely composed by eukaryotes and bacterial diversity is vastly underrepresented3,4.

By avoiding the need for direct experimentation and observation genetic techniques have made it possible to depict the Tree of Life in a more precise way. We can create trees by using molecular methods like the small-subunit ribosomal gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However, there is still much biodiversity to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are often only found in a single specimen5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including numerous bacteria and archaea that have not been isolated, and whose diversity is poorly understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine whether specific habitats require protection. This information can be utilized in a range of ways, from identifying the most effective medicines to combating disease to enhancing the quality of the quality of crops. The information is also incredibly valuable in conservation efforts. It helps biologists discover areas that are likely to have cryptic species, which may have important metabolic functions, and could be susceptible to human-induced change. Although funds to protect biodiversity are crucial but the most effective way to ensure the preservation of biodiversity around the world is for more people living in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between different organisms. Scientists can create a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological differences or similarities. The concept of phylogeny is fundamental to understanding evolution, biodiversity and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestral. These shared traits could be analogous or homologous. Homologous traits share their underlying evolutionary path, while analogous traits look like they do, but don't have the identical origins. Scientists organize similar traits into a grouping called a the clade. For example, all of the organisms in a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor that had eggs. A phylogenetic tree can be constructed by connecting clades to identify the species who are the closest to one another.

For a more detailed and accurate phylogenetic tree, scientists make use of molecular data from DNA or RNA to identify the relationships among organisms. This information is more precise and gives evidence of the evolutionary history of an organism. The use of molecular data lets researchers identify the number of organisms who share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, a kind of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more similar in one species than another, obscuring the phylogenetic signal. However, this issue can be solved through the use of methods like cladistics, which include a mix of similar and homologous traits into the tree.

In addition, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists make decisions about the species they should safeguard from extinction. It is ultimately the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its requirements, 에볼루션 무료체험 the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that can be passed on to the offspring.

In the 1930s and 1940s, concepts from a variety of fields -- including natural selection, genetics, and particulate inheritance--came together to form the current evolutionary theory synthesis that explains how evolution happens through the variations of genes within a population and how those variants change over time as a result of natural selection. This model, called genetic drift, mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and can be mathematically described.

Recent advances in the field of evolutionary developmental biology have shown how variations can be introduced to a species through genetic drift, mutations, reshuffling genes during sexual reproduction and 에볼루션사이트 the movement between populations. These processes, as well as other ones like directional selection and 에볼루션 카지노 genetic erosion (changes in the frequency of the genotype over time) can result in evolution, which is defined by changes in the genome of the species over time and also the change in phenotype over time (the expression of that genotype in an individual).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking throughout all aspects of biology. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence for evolution increased students' understanding of evolution in a college-level biology class. To find out more about how to teach about evolution, look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution through looking back in the past--analyzing fossils and comparing species. They also study living organisms. However, evolution isn't something that occurred in the past; it's an ongoing process that is taking place in the present. Bacteria mutate and resist antibiotics, 에볼루션 바카라 사이트 viruses reinvent themselves and elude new medications and animals alter their behavior to the changing environment. The changes that result are often easy to see.

It wasn't until the 1980s that biologists began to realize that natural selection was in play. The key is that different characteristics result in different rates of survival and reproduction (differential fitness), and can be transferred from one generation to the next.

In the past, if one allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it might become more common than other allele. Over time, this would mean that the number of moths sporting black pigmentation in a population may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to track evolutionary change when an organism, like bacteria, has a high generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain. samples from each population are taken every day and over 500.000 generations have been observed.

Lenski's research has shown that a mutation can profoundly alter the rate at the rate at which a population reproduces, and consequently the rate at which it evolves. It also demonstrates that evolution is slow-moving, a fact that some people find hard to accept.

Another example of microevolution is how mosquito genes that confer resistance to pesticides are more prevalent in populations in which insecticides are utilized. This is because pesticides cause an exclusive pressure that favors those with resistant genotypes.

The rapidity of evolution has led to an increasing recognition of its importance, especially in a world which is largely shaped by human activities. This includes climate change, pollution, and habitat loss that prevents many species from adapting. Understanding the evolution process will help you make better decisions regarding the future of the planet and its inhabitants.