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The Academy's Evolution Site Biological evolution is a central concept in biology. The Academies have been active for a long time in helping people who are interested in science comprehend the theory of evolution and how it influences all areas of scientific research. This site provides students, teachers and general readers with a wide range of learning resources about evolution. It includes key video clips from NOVA and the WGBH-produced science programs on DVD. Tree of Life The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is seen in a variety of spiritual traditions and cultures as an emblem of unity and love. It also has important practical applications, like providing a framework to understand the evolution of species and how they respond to changes in environmental conditions. Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, based on sampling of different parts of living organisms, or sequences of short fragments of their DNA, significantly increased the variety that could be included in the tree of life2. These trees are largely composed by eukaryotes and bacterial diversity is vastly underrepresented3,4. By avoiding the necessity for direct experimentation and observation, genetic techniques have made it possible to depict the Tree of Life in a more precise manner. In particular, molecular methods allow us to build trees by using sequenced markers like the small subunit ribosomal RNA gene. The Tree of Life has been significantly expanded by genome sequencing. However, there is still much diversity to be discovered. This is especially true for microorganisms that are difficult to cultivate, and are usually found in a single specimen5. Recent analysis of all genomes resulted in an unfinished draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that haven't yet been identified or their diversity is not fully understood6. This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if particular habitats need special protection. The information is useful in a variety of ways, including finding new drugs, fighting diseases and enhancing crops. This information is also valuable to conservation efforts. It helps biologists discover areas that are most likely to be home to species that are cryptic, which could have vital metabolic functions and are susceptible to human-induced change. While conservation funds are important, the best method to protect the world's biodiversity is to empower more people in developing nations with the necessary knowledge to act locally and support conservation. Phylogeny A phylogeny is also known as an evolutionary tree, reveals the relationships between groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolution of taxonomic groups based on molecular data and morphological similarities or differences. Phylogeny is crucial in 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 evolved from common ancestral. These shared traits are either analogous or homologous. Homologous characteristics are identical in their evolutionary path. Analogous traits may look like they are however they do not have the same origins. Scientists group similar traits together into a grouping called a the clade. Every organism in a group have a common trait, such as amniotic egg production. They all came from an ancestor who had these eggs. The clades are then connected to form a phylogenetic branch that can determine the organisms with the closest connection to each other. Scientists use DNA or RNA molecular data to build a phylogenetic chart that is more accurate and precise. This information is more precise and gives evidence of the evolution history of an organism. Researchers can use Molecular Data to determine the age of evolution of living organisms and discover how many organisms have a common ancestor. Phylogenetic relationships can be affected by a variety of factors that include phenotypicplasticity. This is a type behaviour that can change due to particular environmental conditions. This can cause a trait to appear more resembling to one species than to the other which can obscure the phylogenetic signal. This problem can be addressed by using cladistics, which incorporates a combination of homologous and analogous traits in the tree. Additionally, phylogenetics can aid in predicting the time and pace of speciation. This information will assist conservation biologists in deciding which species to protect from the threat of extinction. In the end, it is the preservation of phylogenetic diversity which will create an ecosystem that is balanced and complete. Evolutionary Theory The central theme in evolution is that organisms change over time due to their interactions with their environment. A variety of theories about evolution have been developed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve gradually according to its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that can be passed on to the offspring. In the 1930s and 1940s, concepts from a variety of fields—including genetics, natural selection and particulate inheritance—came together to form the current synthesis of evolutionary theory, which defines how evolution occurs through the variation of genes within a population and how those variations change over time due to natural selection. This model, which includes genetic drift, mutations as well as gene flow and sexual selection, can be mathematically described. Recent developments in the field of evolutionary developmental biology have revealed how variations can be introduced to a species by mutations, genetic drift or reshuffling of genes in sexual reproduction and the movement between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time) can lead to evolution which is defined by change in the genome of the species over time, and the change in phenotype as time passes (the expression of that genotype within the individual). Students can better understand the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. In a recent study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution increased their acceptance of evolution during the course of a college biology. For more details about how to teach evolution look up The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education. Evolution in Action Scientists have studied evolution through looking back in the past, studying fossils, and comparing species. They also study living organisms. Evolution is not a past event, but an ongoing process. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. 무료 에볼루션 alter their behavior in the wake of a changing environment. The changes that occur are often evident. It wasn't until late 1980s that biologists began realize that natural selection was in play. The key to this is that different traits result in a different rate of survival and reproduction, and they can be passed down from generation to generation. In the past, when one particular allele, the genetic sequence that defines color in a group of interbreeding organisms, it could quickly become more common than all other alleles. As time passes, this could mean that the number of moths with black pigmentation could increase. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. The ability to observe evolutionary change is easier when a species has a rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from one strain. The samples of each population have been taken regularly, and more than 50,000 generations of E.coli have passed. Lenski's research has revealed that mutations can alter the rate at which change occurs and the efficiency at which a population reproduces. It also demonstrates that evolution takes time, a fact that some people are unable to accept. Another example of microevolution is how mosquito genes that confer resistance to pesticides show up more often in areas where insecticides are employed. That's because the use of pesticides causes a selective pressure that favors those with resistant genotypes. The rapidity of evolution has led to a growing appreciation of its importance especially in a planet that is largely shaped by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding evolution can assist you in making better choices about the future of the planet and its inhabitants.