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The Academy's Evolution Site Biology is one of the most fundamental concepts in biology. The Academies are involved in helping those interested in science to understand evolution theory and how it can be applied throughout all fields of scientific research. This site provides teachers, students and general readers with a variety of learning resources about evolution. It includes important video clips from NOVA and WGBH's science programs on DVD. Tree of Life The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is an emblem of love and unity in many cultures. It also has practical applications, like providing a framework to understand the evolution of species and how they react to changing environmental conditions. Early attempts to describe the world of biology were built on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely on the collection of various parts of organisms or short fragments of DNA have significantly increased the diversity of a tree of Life2. However these trees are mainly composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4. Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods allow us to build trees using sequenced markers like the small subunit ribosomal RNA gene. Despite the dramatic expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is particularly true for microorganisms, which can be difficult to cultivate and are often only present in a single sample5. Recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a variety of archaea, bacteria, and other organisms that haven't yet been isolated, or the diversity of which is not thoroughly understood6. The expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if particular habitats require special protection. The information can be used in a range of ways, from identifying new medicines to combating disease to improving the quality of crops. This information is also extremely beneficial for conservation efforts. It helps biologists discover areas most likely to be home to cryptic species, which could have vital metabolic functions, and could be susceptible to the effects of human activity. While funding to protect biodiversity are essential, the best method to protect the world's biodiversity is to empower more people in developing nations with the information they require to act locally and promote conservation. Phylogeny A phylogeny is also known as an evolutionary tree, reveals the relationships between groups of organisms. Using molecular data similarities and differences in morphology or ontogeny (the process of the development of an organism), scientists can build an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic groups. Phylogeny is essential in understanding evolution, biodiversity and genetics. A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits can be analogous or homologous. Homologous traits share their evolutionary origins, while analogous traits look similar, but do not share the identical origins. Scientists put similar traits into a grouping called a clade. All organisms in a group have a common characteristic, for example, amniotic egg production. They all came from an ancestor that had these eggs. A phylogenetic tree is built by connecting the clades to determine the organisms that are most closely related to one another. For a more detailed and precise phylogenetic tree scientists use molecular data from DNA or RNA to establish the relationships among organisms. This information is more precise and provides evidence of the evolution history of an organism. Researchers can use Molecular Data to calculate the evolutionary age of living organisms and discover the number of organisms that have an ancestor common to all. The phylogenetic relationship can be affected by a number of factors, including the phenomenon of phenotypicplasticity. This is a type behavior that alters as a result of particular environmental conditions. This can cause a trait to appear more similar in one species than another, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous features in the tree. Furthermore, phylogenetics may help predict the length and speed of speciation. This information can assist conservation biologists decide the species they should safeguard from extinction. In the end, it's the preservation of phylogenetic diversity that will result in an ecologically balanced and complete ecosystem. Evolutionary Theory The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can cause changes that are passed on to the next generation. In the 1930s and 1940s, concepts from various fields, such as genetics, natural selection, and particulate inheritance, came together to create a modern evolutionary theory. This defines how evolution happens through the variations in genes within the population, and how these variations alter over time due to natural selection. This model, known as genetic drift mutation, gene flow and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically described. Recent discoveries in the field of evolutionary developmental biology have shown how variations can be introduced to a species through mutations, genetic drift and reshuffling of genes during sexual reproduction and migration between populations. These processes, as well as others such as the directional selection process and the erosion of genes (changes to the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in individuals). Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny and evolution. In a recent study by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their acceptance of evolution during the course of a college biology. For more details on how to teach evolution, see The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education. Evolution in Action Traditionally, scientists have studied evolution through looking back—analyzing fossils, comparing species and observing living organisms. Evolution is not a distant moment; it is an ongoing process. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior because of a changing world. The changes that occur are often visible. 에볼루션 wasn't until late-1980s that biologists realized that natural selection can be observed in action as well. The reason is that different traits have different rates of survival and reproduction (differential fitness), and can be transferred from one generation to the next. In the past, if one particular allele—the genetic sequence that determines coloration—appeared in a group of interbreeding species, it could rapidly become more common than the other alleles. In time, this could mean that the number of moths sporting black pigmentation in a population could increase. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. It is easier to observe evolutionary change when a species, such as 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 of each population are taken every day, and over fifty thousand generations have been observed. Lenski's research has revealed that mutations can alter the rate at which change occurs and the efficiency of a population's reproduction. It also shows that evolution takes time—a fact that some are unable to accept. Another example of microevolution is that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides are employed. Pesticides create an exclusive pressure that favors those with resistant genotypes. The rapid pace at which evolution can take place has led to an increasing recognition of its importance in a world shaped by human activity, including climate changes, pollution and the loss of habitats which prevent many species from adjusting. Understanding the evolution process will help us make better decisions regarding the future of our planet as well as the lives of its inhabitants.