The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have been for a long time involved in helping those interested in science understand the concept of evolution and how it influences all areas of scientific research.
This site provides a wide range of tools for teachers, students, and general readers on evolution. It includes key video clip 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 religions and cultures as a symbol of unity and love. It can be used in many practical ways as well,
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The first attempts at depicting the world of biology focused on separating organisms into distinct categories which had been identified by their physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms or
에볼루션 코리아 small fragments of their DNA, significantly increased the variety that could be represented in a tree of life2. These trees are largely composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. Trees can be constructed using molecular methods like the small-subunit ribosomal gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and are usually found in one sample5. A recent analysis of all genomes resulted in a rough draft of the Tree of Life. This includes a wide range of bacteria, 에볼루션
바카라 에볼루션 무료 (
evolutioncasinosite44386.wikitelevisions.com) archaea and other organisms that haven't yet been isolated, or whose diversity has not been well understood6.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine whether specific habitats require special protection. The information can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing crops. It is also beneficial for conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species that could have important metabolic functions that could be at risk from anthropogenic change. While funding to protect biodiversity are important, the best way to conserve the world's biodiversity is to empower more people in developing nations with the knowledge they need to take action locally and encourage conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the connections between various groups of organisms. Scientists can build an phylogenetic chart which shows the evolutionary relationships between taxonomic categories using molecular information and morphological differences or similarities. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.
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. These shared traits can be homologous, or analogous. Homologous traits are identical in their evolutionary roots and analogous traits appear like they do, but don't have the same ancestors. Scientists group similar traits together into a grouping referred to as a clade. All members of a clade share a characteristic, for example, amniotic egg production. They all came from an ancestor with these eggs. A phylogenetic tree is then constructed by connecting the clades to identify the species which are the closest to one another.
Scientists make use of molecular DNA or RNA data to construct a phylogenetic graph which is more precise and detailed. This information is more precise than morphological data and provides evidence of the evolution history of an individual or group. The analysis of molecular data can help researchers identify the number of organisms that have a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships between species are influenced by many factors, including phenotypic plasticity a kind 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, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous traits in the tree.
Furthermore, phylogenetics may aid in predicting the length and
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Evolutionary Theory
The central theme of evolution is that organisms acquire various characteristics over time due to their interactions with their surroundings. A variety of theories about evolution have been proposed by a wide range 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, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that could be passed onto offspring.
In the 1930s and 1940s, concepts from various fields, including genetics, natural selection and particulate inheritance, merged to form a modern synthesis of evolution theory. This explains how evolution is triggered by the variation of genes in the population and how these variants change with time due to natural selection. This model, which is known as genetic drift, mutation, gene flow and sexual selection, is the foundation of current evolutionary biology, and can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species via mutation, genetic drift, and reshuffling of genes in sexual reproduction, as well as through the movement of populations. These processes, in conjunction with other ones like the directional selection process and the erosion of genes (changes in the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time and changes in phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all areas of biology education can increase student understanding of the concepts of phylogeny and evolutionary. In a recent study conducted by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution during the course of a college biology. To find out more about how to teach about evolution, please read The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species, and observing living organisms. But evolution isn't just something that occurred in the past.