sailorgan18

The Academy's Evolution Site Biological evolution is one of the most central concepts in biology. The Academies have been for a long time involved in helping people who are interested in science understand the theory of evolution and how it permeates all areas of scientific exploration. This site provides students, teachers and general readers with a wide range of learning resources 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 is an emblem of love and harmony in a variety of cultures. It has numerous practical applications as well, such as providing a framework to understand the evolution of species and how they respond to changes in environmental conditions. The first attempts to depict the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on the sampling of different parts of organisms or DNA fragments, have greatly increased the diversity of a Tree of Life2. These trees are largely composed of eukaryotes, while bacteria are largely underrepresented3,4. Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular techniques such as the small subunit ribosomal gene. 에볼루션 게이밍 of Life has been greatly expanded thanks to genome sequencing. However, there is still much diversity 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 known genomes has produced a rough draft of the Tree of Life, including a large number of bacteria and archaea that have not been isolated and whose diversity is poorly understood6. This expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if specific habitats need special protection. The information can be used in a range of ways, from identifying the most effective treatments to fight disease to enhancing the quality of crop yields. The information is also beneficial in conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species that could have important metabolic functions that may be at risk from anthropogenic change. While conservation funds are important, the best way to conserve the world's biodiversity is to empower the people of developing nations with the necessary knowledge to act locally and promote conservation. Phylogeny A phylogeny, also called an evolutionary tree, reveals the connections between different groups of organisms. By using molecular information as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree that illustrates the evolutionary relationships between taxonomic groups. The concept of phylogeny is fundamental to understanding evolution, biodiversity and genetics. A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits could be analogous or homologous. Homologous traits share their underlying evolutionary path while analogous traits appear similar, but do not share the same ancestors. Scientists put similar traits into a grouping referred to as a Clade. For instance, all of the organisms that make up a clade have the characteristic of having amniotic egg and evolved from a common ancestor who had eggs. A phylogenetic tree is built by connecting the clades to determine the organisms which are the closest to each other. To create a more thorough and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to establish the connections between organisms. This information is more precise and gives evidence of the evolution of an organism. The use of molecular data lets researchers determine the number of species who share the same ancestor and estimate their evolutionary age. The phylogenetic relationship can be affected by a variety of factors that include the phenomenon of phenotypicplasticity. This is a kind of behaviour that can change in response to particular environmental conditions. This can make a trait appear more similar to a species than to another which can obscure the phylogenetic signal. However, this issue can be reduced by the use of methods such as cladistics which incorporate a combination of homologous and analogous features into the tree. Additionally, phylogenetics can help determine the duration and rate of speciation. This information can assist conservation biologists in making choices about which species to save from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which will result in an ecologically balanced and complete ecosystem. Evolutionary Theory The central theme of evolution is that organisms develop distinct characteristics over time based on their interactions with their surroundings. Several theories of evolutionary change have been developed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that can be passed onto offspring. In the 1930s and 1940s, ideas from various fields, including genetics, natural selection, and particulate inheritance – came together to create the modern synthesis of evolutionary theory that explains how evolution occurs through the variations of genes within a population, and how those variants change over time due to natural selection. This model, which incorporates genetic drift, mutations, gene flow and sexual selection is mathematically described. Recent developments in the field of evolutionary developmental biology have shown that variations can be introduced into a species via mutation, genetic drift and reshuffling of genes in sexual reproduction, and also by migration between populations. These processes, as well as other ones like the directional selection process and the erosion of genes (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in phenotype (the expression of genotypes within individuals). Students can better understand phylogeny by incorporating evolutionary thinking in all aspects of biology. In a recent study by Grunspan et al. It was found that teaching students about the evidence for evolution boosted their understanding of evolution during the course of a college biology. For more information on how to teach about evolution, please look up The Evolutionary Potential in All Areas of Biology and 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 observe living organisms. But evolution isn't a thing that occurred in the past. It's an ongoing process, happening in the present. Bacteria transform and resist antibiotics, viruses evolve and are able to evade new medications and animals change their behavior in response to the changing environment. The changes that result are often evident. But it wasn't until the late-1980s that biologists realized that natural selection could be seen in action, as well. The key is that various characteristics result in different rates of survival and reproduction (differential fitness) and can be passed down from one generation to the next. In the past when one particular allele – the genetic sequence that defines color in a group of interbreeding species, it could quickly become more prevalent than other alleles. In time, this could mean that the number of moths sporting 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. It is easier to track evolutionary change when an organism, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. Samples of each population have been collected regularly and more than 50,000 generations of E.coli have been observed to have passed. Lenski's research has demonstrated that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows that evolution takes time, a fact that is hard for some to accept. Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides have been used. This is because the use of pesticides causes a selective pressure that favors people who have resistant genotypes. The speed at which evolution takes place has led to a growing recognition of its importance in a world that is shaped by human activity, including climate change, pollution, and the loss of habitats that prevent many species from adapting. Understanding the evolution process will aid you in making better decisions about the future of the planet and its inhabitants.