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The Academy's Evolution Site Biological evolution is a central concept in biology. The Academies are committed to helping those interested in science understand evolution theory and how it can be applied across all areas of scientific research. This site provides teachers, students and general readers with a variety of educational resources on evolution. 에볼루션 바카라 무료 has the most important video clips from NOVA and WGBH-produced 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 harmony in a variety of cultures. It can be used in many practical ways as well, including providing a framework to understand the evolution of species and how they respond to changing environmental conditions. Early attempts to represent the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods depend on the collection of various parts of organisms or fragments of DNA have greatly increased the diversity of a tree of Life2. However the trees are mostly comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4. Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. Trees can be constructed using molecular methods, such as the small-subunit ribosomal gene. Despite the dramatic growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially the case for microorganisms which are difficult to cultivate and are typically found in a single specimen5. A recent analysis of all genomes produced a rough draft of a Tree of Life. This includes a large number of archaea, bacteria, and other organisms that have not yet been isolated or the diversity of which is not well understood6. This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if certain habitats require special protection. This information can be utilized in a variety of ways, including identifying new drugs, combating diseases and improving crops. This information is also extremely useful to conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which may perform important metabolic functions, and could be susceptible to the effects of human activity. While funds to protect biodiversity are important, the most effective way to conserve the world's biodiversity is to equip more people in developing nations with the knowledge they need to act locally and support conservation. Phylogeny A phylogeny, also known as an evolutionary tree, reveals the connections between various groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic groups using molecular data and morphological similarities or differences. The concept of phylogeny is fundamental to 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 with similar traits that evolved from common ancestral. 에볼루션 바카라 체험 shared traits can be either analogous or homologous. Homologous traits share their evolutionary origins while analogous traits appear similar but do not have the same origins. Scientists combine similar traits into a grouping called a clade. For example, all of the organisms in a clade have the characteristic of having amniotic egg and evolved from a common ancestor which had these eggs. The clades are then linked to form a phylogenetic branch to determine the organisms with the closest connection to each other. For a more detailed and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the relationships between organisms. This information is more precise and provides evidence of the evolution history of an organism. Molecular data allows researchers to identify the number of organisms who share the same ancestor and estimate their evolutionary age. The phylogenetic relationships between organisms are influenced by many factors including phenotypic plasticity, a type of behavior that changes in response to specific environmental conditions. This can cause a particular trait to appear more similar to one species than another, clouding the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates an amalgamation of analogous and homologous features in the tree. In addition, phylogenetics can aid in predicting the length and speed of speciation. This information can assist conservation biologists in deciding which species to save from the threat of extinction. In the end, it is the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced. Evolutionary Theory The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution have been developed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that could be passed on to offspring. In the 1930s and 1940s, theories from a variety of fields—including natural selection, genetics, and particulate inheritance—came together to form the current evolutionary theory synthesis which explains how evolution is triggered by the variations of genes within a population and how those variants change over time as a result of natural selection. This model, known as genetic drift or mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and can be mathematically described. Recent discoveries in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species via genetic drift, mutation, and reshuffling of genes during sexual reproduction, as well as by migration between populations. These processes, along with 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 the genotype in the individual). Incorporating evolutionary thinking into all aspects of biology education can increase student understanding of the concepts of phylogeny as well as evolution. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence for evolution increased students' acceptance of evolution in a college biology course. For more information on how to teach about evolution, look up The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education. Evolution in Action Scientists have looked at evolution through the past, studying fossils, and comparing species. They also study living organisms. But evolution isn't a thing that occurred in the past; it's an ongoing process, that is taking place today. Bacteria mutate and resist antibiotics, viruses reinvent themselves and elude new medications and animals alter their behavior to the changing environment. The results are often evident. It wasn't until late 1980s that biologists realized that natural selection could be observed in action as well. The main reason is that different traits result in an individual rate of survival and reproduction, and they can be passed on from one generation to the next. In the past, if one allele – the genetic sequence that determines colour – was present in a population of organisms that interbred, it might become more common than other allele. As time passes, this could mean that the number of moths with 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. The ability to observe evolutionary change is easier when a particular species has a fast generation turnover, as with bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples from each population are taken every day, and over fifty thousand generations have passed. Lenski's work has demonstrated that mutations can drastically alter the speed at the rate at which a population reproduces, and consequently, the rate at which it changes. It also shows evolution takes time, something that is hard for some to accept. Another example of microevolution is the way mosquito genes that are resistant to pesticides appear more frequently in populations in which insecticides are utilized. This is due to the fact that the use of pesticides causes a selective pressure that favors people with resistant genotypes. The rapid pace at which evolution can take place has led to a growing recognition of its importance in a world shaped by human activity, including climate change, pollution and the loss of habitats which prevent the species from adapting. Understanding the evolution process can assist you in making better choices regarding the future of the planet and its inhabitants.