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The Academy's Evolution Site Biological evolution is a central concept in biology. The Academies are involved in helping those who are interested in science to understand evolution theory and how it is incorporated in all areas of scientific research. This site provides students, teachers and general readers with a variety of learning resources about evolution. It contains the most important video clips from NOVA and WGBH's science programs on DVD. Tree of Life The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and unity in many cultures. It has many practical applications as well, including providing a framework for understanding the evolution of species and how they react to changes in environmental conditions. Early attempts to represent the biological world were built on categorizing organisms based on their physical and metabolic characteristics. These methods rely on the sampling of different parts of organisms or short fragments of DNA have greatly increased the diversity of a Tree of Life2. These trees are mostly populated of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4. By avoiding the need for direct experimentation and observation, genetic techniques have allowed us to depict the Tree of Life in a more precise way. In particular, molecular methods allow us to build trees using sequenced markers like the small subunit ribosomal gene. Despite the dramatic expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is especially true of microorganisms that are difficult to cultivate and are often only found in a single specimen5. Recent analysis of all genomes resulted in an unfinished draft of the Tree of Life. This includes a wide range of archaea, bacteria, and other organisms that have not yet been isolated, or the diversity of which is not fully understood6. The expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine if certain habitats require special protection. The information can be used in a variety of ways, from identifying new remedies to fight diseases to enhancing the quality of crops. The information is also valuable in conservation efforts. It can aid biologists in identifying the areas that are most likely to contain cryptic species that could have important metabolic functions that could be vulnerable to anthropogenic change. While conservation funds are important, the most effective method to protect the biodiversity of the world is to equip more people in developing nations with the necessary knowledge to take action locally and encourage conservation. Phylogeny A phylogeny (also known as an evolutionary tree) shows the relationships between different organisms. Scientists can build an phylogenetic chart which shows the evolution of taxonomic groups based on molecular data and morphological similarities or differences. Phylogeny is essential in understanding the evolution of biodiversity, evolution 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 are similar in their evolutionary path. Analogous traits may look like they are, but they do not have the same ancestry. Scientists combine similar traits into a grouping known as a the clade. For example, all of the organisms in a clade have the characteristic of having amniotic eggs and evolved from a common ancestor that had eggs. A phylogenetic tree can be built by connecting the clades to identify the organisms which are the closest to each other. For a more detailed and accurate phylogenetic tree, scientists make use of molecular data from DNA or RNA to identify the relationships between organisms. This data is more precise than morphological data and provides evidence of the evolutionary background of an organism or group. Researchers can use Molecular Data to determine the evolutionary age of living organisms and discover how many organisms share an ancestor common to all. The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic flexibility, a type of behavior that alters in response to unique environmental conditions. This can cause a trait to appear more like a species another, clouding the phylogenetic signal. However, this issue can be reduced by the use of techniques such as cladistics that include a mix of homologous and analogous features into the tree. Additionally, phylogenetics aids predict the duration and rate at which speciation takes place. This information will assist conservation biologists in deciding which species to save from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will create an ecologically balanced and complete ecosystem. Evolutionary Theory The fundamental concept of evolution is that organisms develop distinct characteristics over time as a result of their interactions with their surroundings. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would develop according to its own requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of traits can lead to changes that can be passed on to future generations. In the 1930s and 1940s, concepts from a variety of 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 due to natural selection. This model, known as genetic drift mutation, gene flow, and sexual selection, is the foundation of the current evolutionary biology and can be mathematically described. Recent developments in evolutionary developmental biology have revealed the ways in which variation can be introduced to a species via mutations, genetic drift, reshuffling genes during sexual reproduction, and even migration between populations. These processes, along with others 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 the change in phenotype as time passes (the expression of the genotype in the individual). Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence supporting evolution increased students' understanding of evolution in a college biology class. For 에볼루션 무료체험 on how to teach 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 Scientists have traditionally studied evolution by looking in the past—analyzing fossils and comparing species. They also study living organisms. Evolution is not a distant event; it is an ongoing process that continues to be observed today. Bacteria evolve and resist antibiotics, viruses re-invent themselves and escape new drugs and animals change their behavior in response to the changing climate. The results are often evident. However, it wasn't until late-1980s that biologists realized that natural selection could be seen in action, as well. The main reason is that different traits can confer an individual rate of survival as well as reproduction, and may be passed down from one generation to the next. In the past, if a certain allele – the genetic sequence that determines colour appeared in a population of organisms that interbred, it might become more common than other allele. Over time, that would mean that the number of black moths in the population 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 particular species has a rapid turnover of its generation, as with bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. Samples from each population have been taken regularly and more than 50,000 generations of E.coli have passed. Lenski's research has demonstrated that mutations can alter the rate of change and the effectiveness at which a population reproduces. It also shows that evolution takes time, a fact that some find difficult to accept. Another example of microevolution is the way mosquito genes for resistance to pesticides show up more often in areas where insecticides are employed. 에볼루션 바카라 무료 is because pesticides cause an enticement that favors individuals who have resistant genotypes. The rapid pace of evolution taking place has led to an increasing appreciation of its importance in a world shaped by human activity, including climate change, pollution, and the loss of habitats that prevent many species from adapting. Understanding the evolution process will assist you in making better choices about the future of our planet and its inhabitants.