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The Academy's Evolution Site Biology is a key concept in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it affects all areas of scientific research. This site provides teachers, students and general readers with a range of educational resources on evolution. It includes key 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 an emblem of love and unity across many cultures. It has many practical applications as well, such as providing a framework to understand the history of species, and how they respond to changes in environmental conditions. 에볼루션 블랙잭 to depict the world of biology focused on categorizing organisms into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods depend on the sampling of different parts of organisms or DNA fragments, have greatly increased the diversity of a Tree of Life2. These trees are mostly populated by eukaryotes, and the diversity of bacterial species is greatly 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 manner. In particular, molecular methods enable us to create trees by using sequenced markers like the small subunit ribosomal RNA gene. The Tree of Life has been greatly expanded thanks to genome sequencing. However, there is still much biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are usually only found in a single sample5. A recent analysis of all genomes known to date has created a rough draft of the Tree of Life, including numerous bacteria and archaea that are not isolated and whose diversity is poorly understood6. This expanded Tree of Life is particularly useful in assessing the diversity of an area, which can help to determine if specific habitats require special protection. This information can be utilized in a variety of ways, from identifying new medicines to combating disease to enhancing the quality of crop yields. It is also beneficial to conservation efforts. It can aid biologists in identifying areas that are most likely to be home to cryptic species, which may perform important metabolic functions and are susceptible to human-induced change. While funding to protect biodiversity are important, the most effective method to preserve the world's biodiversity is to empower the people of developing nations with the necessary knowledge to take action locally and encourage conservation. Phylogeny A phylogeny is also known as an evolutionary tree, illustrates the relationships between various groups of organisms. Using molecular data as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree that illustrates the evolutionary relationships between taxonomic categories. Phylogeny is essential in understanding evolution, biodiversity and genetics. A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms with similar traits and have evolved from a common ancestor. These shared traits may be analogous or homologous. Homologous traits are the same in their evolutionary paths. Analogous traits could appear like they are, but they do not share the same origins. Scientists combine similar traits into a grouping called a clade. All organisms in a group share a characteristic, like amniotic egg production. They all derived from an ancestor who had these eggs. The clades then join to form a phylogenetic branch to determine the organisms with the closest relationship. Scientists use molecular DNA or RNA data to create a phylogenetic chart that is more precise and detailed. This data is more precise than morphological data and provides evidence of the evolution history of an individual or group. Researchers can utilize Molecular Data to calculate the evolutionary age of organisms and identify the number of organisms that have an ancestor common to all. The phylogenetic relationships of organisms can be affected by a variety of factors, including phenotypic plasticity a type of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more like a species another, clouding the phylogenetic signal. This problem can be mitigated by using cladistics. This is a method that incorporates the combination of analogous and homologous features in the tree. Furthermore, phylogenetics may help predict the length and speed of speciation. This information can help conservation biologists make decisions about which species they should protect from extinction. In the end, it is the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced. Evolutionary Theory The central theme of evolution is that organisms acquire various characteristics over time as a result of their interactions with their surroundings. A variety of theories about evolution have been proposed 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 requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that could be passed on to the offspring. In the 1930s and 1940s, theories from various fields, including natural selection, genetics & particulate inheritance, merged to form a contemporary synthesis of evolution theory. This defines how evolution occurs by the variation of genes in a population and how these variants change over time as a result of natural selection. This model, which incorporates genetic drift, mutations as well as gene flow and sexual selection, can be mathematically described. Recent developments in evolutionary developmental biology have demonstrated how variations can be introduced to a species by mutations, genetic drift, reshuffling genes during sexual reproduction and the movement between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution, which is defined by change in the genome of the species over time and also by changes 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 conducted by Grunspan and colleagues, for example revealed that teaching students about the evidence supporting evolution increased students' acceptance of evolution in a college-level biology class. For more details about how to teach evolution, see The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily A Framework for Integrating Evolution into Life Sciences Education. Evolution in Action Scientists have looked at evolution through the past—analyzing fossils and comparing species. They also observe living organisms. Evolution is not a distant event, but an ongoing process. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior in the wake of the changing environment. The changes that occur are often apparent. It wasn't until the late 1980s that biologists began realize that natural selection was in action. The key is the fact that different traits can confer the ability to survive at different rates and reproduction, and can be passed down from one generation to another. In the past, if one particular allele, the genetic sequence that defines color in a population of interbreeding organisms, it could quickly become more common than the other alleles. In time, this could mean that the number of moths that have black pigmentation in a group may increase. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. It is easier to observe evolution when an organism, like bacteria, has a high generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples from each population are taken on a regular basis and more than 500.000 generations have passed. Lenski's research has revealed that mutations can drastically alter the speed at which a population reproduces and, consequently the rate at which it alters. It also demonstrates that evolution takes time, a fact that some people find difficult 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 because the use of pesticides causes a selective pressure that favors individuals with 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 the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution can aid you in making better decisions regarding the future of the planet and its inhabitants.