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The Academy's Evolution Site Biology is a key concept in biology. The Academies have been for a long time involved in helping people who are interested in science comprehend the concept of evolution and how it affects every area of scientific inquiry. This site provides teachers, students and general readers with a variety of learning resources about 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, represents the interconnectedness of all life. It is an emblem of love and harmony in a variety of cultures. It also has practical uses, like providing a framework for understanding the history of species and how they react to changing environmental conditions. The earliest attempts to depict the world of biology focused on separating species into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms or on small fragments of their DNA greatly increased the variety of organisms that could be represented in the tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4. Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular techniques allow us to build trees by using sequenced markers, such as the small subunit of ribosomal RNA gene. Despite the massive expansion of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and which are usually only present in a single sample5. Recent analysis of all genomes resulted in an initial draft of a Tree of Life. This includes a large number of archaea, bacteria and other organisms that have not yet been identified or their diversity is not thoroughly understood6. This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine whether specific habitats require special protection. The information can be used in a variety of ways, from identifying the most effective remedies to fight diseases to improving crops. The information is also beneficial for conservation efforts. It helps biologists discover areas most likely to be home to cryptic species, which could perform important metabolic functions and are susceptible to changes caused by humans. While conservation funds are important, the best method to preserve the world's biodiversity is to equip more people in developing countries with the information they require to act locally and promote conservation. Phylogeny A phylogeny (also known as an evolutionary tree) depicts the relationships between different organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationship of taxonomic groups using molecular data and morphological differences or similarities. Phylogeny is essential in understanding evolution, biodiversity and genetics. A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestors. These shared traits can be either analogous or homologous. Homologous traits are identical in their underlying evolutionary path, while analogous traits look similar but do not have the same origins. Scientists group similar traits together into a grouping known as a clade. All organisms in a group have a common characteristic, like amniotic egg production. They all derived from an ancestor that had these eggs. The clades are then connected to form a phylogenetic branch to determine the organisms with the closest connection to each other. For a more detailed and accurate phylogenetic tree, scientists use molecular data from DNA or RNA to identify the relationships between organisms. This information is more precise than the morphological data and provides evidence of the evolutionary history of an individual or group. Researchers can use Molecular Data to estimate the evolutionary age of living organisms and discover the number of organisms that share an ancestor common to all. The phylogenetic relationship can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is a type of behaviour that can change due to unique environmental conditions. This can cause a particular trait to appear more like a species other species, which can obscure the phylogenetic signal. However, this problem can be reduced by the use of techniques such as cladistics which combine similar and homologous traits into the tree. In addition, phylogenetics can aid in predicting the length and speed of speciation. This information can assist conservation biologists decide the species they should safeguard from the threat of extinction. It is ultimately the preservation of phylogenetic diversity that will create a complete and balanced ecosystem. Evolutionary Theory The main idea behind evolution is that organisms alter over time because of their interactions with their environment. A variety of theories about evolution have been developed by a wide range of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop 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 cause changes that could be passed on to the offspring. In the 1930s and 1940s, concepts from various fields, including genetics, natural selection, and particulate inheritance – came together to form the current evolutionary theory synthesis, which defines how evolution happens through the variation of genes within a population, and how these variants change in time as a result of natural selection. This model, which includes mutations, genetic drift, gene flow and sexual selection can be mathematically described. Recent developments in evolutionary developmental biology have shown the ways in which variation can be introduced to a species via genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of the genotype over time), can lead to evolution that is defined as change in the genome of the species over time, and also by changes in phenotype over time (the expression of the genotype in the individual). Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. For more details about how to teach evolution look up The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education. Evolution in Action Traditionally scientists have studied evolution by looking back—analyzing fossils, comparing species and studying living organisms. Evolution is not a distant event; it is a process that continues today. Bacteria transform and resist antibiotics, viruses evolve and are able to evade new medications, and animals adapt their behavior in response to the changing environment. The resulting changes are often easy to see. It wasn't until the 1980s that biologists began realize that natural selection was also in play. The key is the fact that different traits result in an individual rate of survival as well as reproduction, and may be passed down from one generation to the next. In the past, if one allele – the genetic sequence that determines color – was found in a group of organisms that interbred, it could be more common than other allele. As time passes, this could mean that the number of moths with 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 evolution when an organism, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from one strain. Samples of each population were taken frequently and more than 500.000 generations of E.coli have passed. 에볼루션 has shown that mutations can alter the rate at which change occurs and the effectiveness at which a population reproduces. It also shows that evolution takes time, a fact that many are unable to accept. Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in areas where insecticides are used. simply click the next document is due to pesticides causing an exclusive pressure that favors those who have resistant genotypes. The rapidity of evolution has led to a growing recognition of its importance particularly in a world which is largely shaped by human activities. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding evolution can help us make smarter decisions regarding the future of our planet and the life of its inhabitants.