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The Academy's Evolution Site The concept of biological evolution is a fundamental concept in biology. The Academies are committed to helping those who are interested in science learn about the theory of evolution and how it can be applied across all areas of scientific research. This site provides students, teachers and general readers with a wide range of learning resources about evolution. It has 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 represents the interconnectedness of life. It is an emblem of love and unity across many cultures. It also has many practical applications, such as providing a framework for understanding the history of species and how they respond to changing environmental conditions. The first attempts at depicting the biological world focused on categorizing species into distinct categories that were distinguished by physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of living organisms or sequences of small fragments of their DNA, greatly increased the variety of organisms that could be included in the tree of life2. However, these trees are largely made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4. By avoiding the need for direct observation and experimentation, genetic techniques have enabled us to depict the Tree of Life in a more precise way. Particularly, molecular techniques enable us to create trees using sequenced markers like the small subunit of ribosomal RNA gene. Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. This is especially relevant to microorganisms that are difficult to cultivate and are typically found in a single specimen5. Recent analysis of all genomes resulted in a rough draft of the Tree of Life. This includes a large number of archaea, bacteria and other organisms that haven't yet been identified or their diversity is not thoroughly understood6. This expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine if certain habitats require protection. This information can be used in a variety of ways, from identifying the most effective medicines to combating disease to improving the quality of crops. This information is also useful in conservation efforts. It can aid biologists in identifying areas that are most likely to be home to cryptic species, which could perform important metabolic functions, and could be susceptible to human-induced change. Although funds to safeguard biodiversity are vital but the most effective way to preserve the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within. Phylogeny A phylogeny is also known as an evolutionary tree, illustrates the relationships between various groups of organisms. Scientists can create a phylogenetic chart that shows the evolutionary relationships between taxonomic groups based on molecular data and morphological differences or similarities. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity and evolution. A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestors. These shared traits may be analogous, or homologous. Homologous traits are identical in their underlying evolutionary path while analogous traits appear similar but do not have the same origins. Scientists group similar traits into a grouping known as a Clade. Every organism in a group share a characteristic, like amniotic egg production. They all came from an ancestor that had these eggs. The clades then join to form a phylogenetic branch to determine the organisms with the closest relationship to. Scientists make use of DNA or RNA molecular data to build a phylogenetic chart which is more precise and precise. This data is more precise than morphological information and gives evidence of the evolutionary history of an individual or group. Researchers can use Molecular Data to determine the evolutionary age of living organisms and discover how many organisms have an ancestor common to all. The phylogenetic relationships between species can be influenced by several factors, including phenotypic plasticity an aspect of behavior that changes in response to specific environmental conditions. This can cause a particular trait to appear more similar in one species than other species, which can obscure the phylogenetic signal. This problem can be addressed by using cladistics, which incorporates a combination of homologous and analogous features in the tree. In addition, phylogenetics helps determine the duration and speed at which speciation takes place. This information can assist conservation biologists in making decisions about which species to safeguard from 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. Several theories of evolutionary change have been developed by a wide variety of scientists including 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 designed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that could be passed onto offspring. In the 1930s and 1940s, theories from various fields, including natural selection, genetics, and particulate inheritance — came together to form the modern evolutionary theory synthesis which explains how evolution occurs through the variation of genes within a population, and how these variants change in time due to natural selection. This model, which encompasses mutations, genetic drift, gene flow and sexual selection can be mathematically described mathematically. Recent advances in the field of evolutionary developmental biology have shown how variations can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction and the movement between populations. mouse click the up coming post , as well as other ones like directional selection and gene erosion (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time as well as changes in phenotype (the expression of genotypes within individuals). Incorporating evolutionary thinking into all areas of biology education could increase students' understanding of phylogeny and evolutionary. In a study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution increased their acceptance of evolution during an undergraduate biology course. For more details on how to teach about evolution look up The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education. Evolution in Action Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species and studying living organisms. However, evolution isn't something that occurred in the past, it's an ongoing process that is taking place right now. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior in the wake of a changing environment. The changes that result are often visible. But it wasn't until the late 1980s that biologists realized that natural selection can be seen in action, as well. The key is that different traits confer 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 organisms, it could quickly become more common than the other alleles. In time, this could mean that the number of black moths in a population could increase. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. Monitoring evolutionary changes in action is easier when a particular species has a fast generation turnover, as with bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from one strain. The samples of each population were taken frequently and more than 50,000 generations of E.coli have passed. Lenski's research has revealed that a mutation can profoundly alter the efficiency with which a population reproduces—and so, the rate at which it evolves. It also proves that evolution takes time—a fact that some find difficult to accept. Another example of microevolution is the way mosquito genes that are resistant to pesticides appear more frequently in populations where insecticides are used. This is due to pesticides causing an enticement that favors those with resistant genotypes. The speed of evolution taking place has led to a growing awareness of its significance in a world that is shaped by human activity—including climate change, pollution, and the loss of habitats that hinder many species from adapting. Understanding evolution will help us make better decisions regarding the future of our planet and the lives of its inhabitants.