sleepdew4

The Academy's Evolution Site Biological evolution is a central concept in biology. The Academies are committed to helping those who are interested in the sciences understand evolution theory and how it is incorporated across all areas of scientific research. This site provides a wide range of tools for teachers, students as well as general readers about evolution. It contains 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 appears in many cultures and spiritual beliefs as a symbol of unity and love. It also has important practical applications, like providing a framework to understand the evolution of species and how they react to changes in the environment. Early attempts to describe the world of biology were based on categorizing organisms based on their metabolic and physical characteristics. 에볼루션 슬롯게임 , which rely on the collection of various parts of organisms or short fragments of DNA have significantly increased the diversity of a tree of Life2. These trees are mostly populated by eukaryotes, and bacteria are largely underrepresented3,4. Genetic techniques have significantly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. We can create trees by using molecular methods such as the small subunit ribosomal gene. The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much biodiversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate and are typically present in a single sample5. 에볼루션 슬롯게임 of all genomes known to date has created a rough draft of the Tree of Life, including many bacteria and archaea that have not been isolated, and which are not well understood. This expanded Tree of Life can be used to determine the diversity of a specific region and determine if specific habitats need special protection. This information can be used in a range of ways, from identifying new treatments to fight disease to enhancing the quality of crops. It is also useful to conservation efforts. It helps biologists discover areas that are likely to be home to species that are cryptic, which could have vital metabolic functions, and could be susceptible to changes caused by humans. Although funds to protect biodiversity are essential but the most effective way to ensure the preservation of biodiversity around the world 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 (also known as an evolutionary tree) illustrates the relationship between different organisms. By using molecular information similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree that illustrates the evolutionary relationships between taxonomic groups. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics. A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that have evolved from common ancestral. These shared traits may be homologous, or analogous. Homologous traits are identical in their evolutionary origins, while analogous traits look similar, but do not share the same origins. Scientists put similar traits into a grouping referred to as a Clade. For instance, all the organisms that make up a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor which had these eggs. The clades then join to form a phylogenetic branch that can identify organisms that have the closest relationship. Scientists utilize DNA or RNA molecular information to construct a phylogenetic graph which is more precise and detailed. This information is more precise and gives evidence of the evolutionary history of an organism. The use of molecular data lets researchers identify the number of species that have a common ancestor and to estimate their evolutionary age. 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 particular trait to appear more similar to one species than another, obscuring the phylogenetic signal. This issue can be cured by using cladistics, which is a a combination of analogous and homologous features in the tree. Additionally, phylogenetics can aid in predicting the length and speed of speciation. This information can aid conservation biologists to decide which species they should protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will create an ecologically balanced and complete ecosystem. Evolutionary Theory The central theme in evolution is that organisms change over time due to their interactions with their environment. Many scientists have come up with 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 as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can lead to changes that are passed on to the next generation. In the 1930s and 1940s, concepts from various areas, including natural selection, genetics & particulate inheritance, merged to create a modern theorizing of evolution. This explains how evolution occurs by the variation of genes in a population and how these variations change over time as a result of natural selection. This model, called genetic drift or mutation, gene flow, and sexual selection, is the foundation of modern evolutionary biology and can be mathematically explained. Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species by genetic drift, mutation, and reshuffling of genes during sexual reproduction, as well as by migration between populations. These processes, along with others such as directional selection or 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 that genotype within the individual). Students can gain a better understanding of phylogeny by incorporating evolutionary thinking into all areas of biology. A recent study by Grunspan and colleagues, for instance revealed that teaching students about the evidence for evolution increased students' understanding of evolution in a college biology class. For more details about how to teach evolution read 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 traditionally studied evolution through looking back in the past—analyzing fossils and comparing species. They also observe living organisms. Evolution is not a past moment; it is an ongoing process that continues to be observed today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of a changing world. The results are usually easy to see. But it wasn't until the late-1980s that biologists realized that natural selection could be observed in action as well. The key is that various traits confer different rates of survival and reproduction (differential fitness), and can be transferred from one generation to the next. In the past when one particular allele—the genetic sequence that defines color in a population of interbreeding organisms, it might rapidly become more common than other alleles. Over time, that would mean the number of black moths in a particular population could rise. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. Observing evolutionary change in action is easier when a particular species has a rapid generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from one strain. Samples of each population have been taken frequently and more than 500.000 generations of E.coli have passed. Lenski's research has revealed that a mutation can dramatically alter the efficiency with which a population reproduces—and so, the rate at which it changes. It also demonstrates that evolution is slow-moving, a fact that some find hard to accept. Microevolution is also evident in the fact that mosquito genes that confer resistance to pesticides are more common in populations where insecticides are used. This is due to the fact that the use of pesticides creates a selective pressure that favors those with resistant genotypes. The rapid pace of evolution taking place has led to a growing recognition of its importance in a world that is shaped by human activities, including climate changes, pollution and the loss of habitats which 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.