The Academy's Evolution Site
Biology is one of the most central concepts in biology. The Academies are committed to helping those interested in the sciences learn about the theory of evolution and
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This site offers a variety of sources for teachers, students and general readers of evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is used in many religions and cultures as a symbol of unity and love. It also has practical applications, like providing a framework to understand the evolution of species and how they react to changes in environmental conditions.
Early approaches to depicting the biological world focused on the classification of organisms into distinct categories which were distinguished by physical and metabolic characteristics1. These methods,
에볼루션 코리아 based on the sampling of various parts of living organisms or on small fragments of their DNA significantly increased the variety that could be included in the tree of life2. However these trees are mainly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.
Genetic techniques have significantly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques allow us to construct trees by using sequenced markers, such as the small subunit ribosomal gene.
The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of biodiversity to be discovered. This is especially true of microorganisms,
에볼루션 사이트 which can be difficult to cultivate and are often only present in a single specimen5. A recent analysis of all known genomes has produced a rough draft of the Tree of Life, including numerous archaea and bacteria that have not been isolated and their diversity is not fully understood6.
This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if particular habitats require special protection. This information can be used in a range of ways, from identifying new remedies to fight diseases to enhancing the quality of crops. This information is also extremely valuable in conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species with potentially significant metabolic functions that could be vulnerable to anthropogenic change. While funding to protect biodiversity are important, the most effective method to preserve 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 called an evolutionary tree) illustrates the relationship between species. Scientists can create an phylogenetic chart which shows the evolutionary relationships between taxonomic groups using molecular data and morphological differences or similarities. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that have evolved from common ancestors. These shared traits are either homologous or analogous. Homologous traits are similar in their evolutionary roots and analogous traits appear similar but do not have the same ancestors. Scientists combine similar traits into a grouping known as a clade. For instance, all of the species in a clade share the trait of having amniotic eggs and evolved from a common ancestor which had these eggs. The clades then join to form a phylogenetic branch that can determine which organisms have the closest relationship to.
To create a more thorough and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to identify the relationships among organisms. This information is more precise and gives evidence of the evolution of an organism. Researchers can use Molecular Data to calculate the evolutionary age of living organisms and discover how many species share an ancestor common to all.
The phylogenetic relationships between organisms can be affected by a variety of factors, including phenotypic flexibility, a type of behavior that alters 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, which incorporates the combination of homologous and analogous features in the tree.
In addition, phylogenetics can aid in predicting the length and speed of speciation. This information can assist conservation biologists decide which species they should protect from the threat of extinction. In the end, it is the conservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme in evolution is that organisms change over time due to their interactions with their environment. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would develop according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of traits can cause changes that are passed on to the
In the 1930s and 1940s, concepts from various fields, such as genetics, natural selection, and particulate inheritance, merged to form a modern theorizing of evolution. This explains how evolution happens through the variation of genes in the population and how these variations change over time as a result of natural selection. This model, known as genetic drift, mutation, gene flow, and sexual selection, is the foundation of modern evolutionary biology and can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species by mutation, genetic drift and reshuffling of genes in sexual reproduction, and also by migration between populations. These processes, along with others such as directional selection and gene erosion (changes to the frequency of genotypes over time) can lead to evolution. Evolution is defined by changes in the genome over time as well as changes in phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny as well as evolution. In a recent study by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution boosted their acceptance of evolution during a college-level course in biology. For more information on how to teach about evolution, please see The Evolutionary Potential of all Areas of Biology and
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Evolution in Action
Traditionally scientists have studied evolution through studying fossils, comparing species and studying living organisms. Evolution isn't a flims moment; it is a process that continues today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior in the wake of a changing environment. The changes that result are often easy to see.