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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 understand the concept of evolution and how it affects every area of scientific inquiry.

This site provides students, teachers and general readers with a wide range of educational resources on evolution. It includes important video clips from NOVA and WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is seen in a variety of religions and cultures as an emblem of unity and love. It also has important practical uses, like providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.

Early attempts to describe the biological world were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on the sampling of different parts of living organisms or sequences of short fragments of their DNA, greatly increased the variety of organisms that could be included in the tree of life2. These trees are mostly populated of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

By avoiding the need for direct experimentation and observation, genetic techniques have allowed us to represent the Tree of Life in a more precise way. Trees can be constructed using molecular techniques, such as the small-subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is a lot of diversity to be discovered. This is especially true of microorganisms, 에볼루션 바카라 which can be difficult to cultivate and are often only found in a single sample5. A recent analysis of all known genomes has produced 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 is particularly useful in assessing the diversity of an area, helping to determine whether specific habitats require protection. The information can be used in a variety of ways, from identifying the most effective remedies to fight diseases to improving the quality of crops. This information is also beneficial for conservation efforts. It helps biologists discover areas that are most likely to have cryptic species, which could have vital metabolic functions, and could be susceptible to human-induced change. Although funds to protect biodiversity are essential however, the most effective method to ensure the preservation of biodiversity around the world is for more people in developing countries to be equipped with the knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny, 무료에볼루션 also known as an evolutionary tree, shows the relationships between different groups of organisms. Scientists can construct an phylogenetic chart which shows the evolution of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny is essential in understanding biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits could be homologous, or analogous. Homologous traits are similar in their underlying evolutionary path, while analogous traits look like they do, but don't have the same origins. Scientists put similar traits into a grouping referred to as a clade. For instance, all the organisms in a clade share the trait of having amniotic egg and evolved from a common ancestor which had these eggs. The clades are then connected to create a phylogenetic tree to determine the organisms with the closest relationship to.

For a more detailed and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the relationships among organisms. This information is more precise and provides evidence of the evolution history of an organism. Researchers can use Molecular Data to calculate the age of evolution of organisms and identify how many organisms have an ancestor common to all.

The phylogenetic relationships between organisms are influenced by many factors including phenotypic plasticity, a kind of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to a species than to the other and obscure the phylogenetic signals. However, this issue can be solved through the use of techniques such as cladistics which incorporate a combination of homologous and analogous features into the tree.

Furthermore, phylogenetics may help predict the time and pace of speciation. This information will assist conservation biologists in making choices about which species to save from the threat of extinction. In the end, it is the conservation of phylogenetic variety that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme in evolution is that organisms alter over time because of their interactions with their environment. Several theories of evolutionary change 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 conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that can be passed on to the offspring.

In the 1930s and 1940s, theories from a variety of fields -- including genetics, natural selection, and particulate inheritance--came together to form the modern evolutionary theory synthesis that explains how evolution happens through the variations of genes within a population and how those variants change in time as a result of natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is a key element of current evolutionary biology, and is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species through mutation, 에볼루션 바카라사이트 바카라 체험 (http://172.105.35.230/) genetic drift, and reshuffling of genes during sexual reproduction, and also by migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time) can result in 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).

Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny and evolution. In a recent study conducted by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution during a college-level course in biology. For more information on how to teach evolution look up The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also study living organisms. But evolution isn't a thing that happened in the past; it's an ongoing process that is taking place right now. Bacteria evolve and resist antibiotics, viruses re-invent themselves and are able to evade new medications, and animals adapt their behavior in response to the changing climate. The changes that result are often apparent.

It wasn't until late 1980s that biologists began to realize that natural selection was also in play. The key is that various traits confer different rates of survival and reproduction (differential fitness), and can be passed from one generation to the next.

In the past when one particular allele, the genetic sequence that determines coloration--appeared in a population of interbreeding species, 무료에볼루션 it could quickly become more common than all other alleles. As time passes, this could mean that the number of moths sporting 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 track evolution when a species, such as 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 of each are taken on a regular basis and over 50,000 generations have now passed.

Lenski's research has shown that a mutation can dramatically alter the speed at which a population reproduces and, 무료에볼루션 consequently the rate at which it changes. It also demonstrates that evolution takes time, a fact that is difficult for some to accept.

Another example of microevolution is that mosquito genes that are resistant to pesticides are more prevalent in populations where insecticides are employed. This is due to the fact that the use of pesticides creates a selective pressure that favors people with resistant genotypes.

The rapid pace at which evolution can take place has led to a growing appreciation of its importance in a world that is shaped by human activity--including climate change, pollution, and the loss of habitats that prevent the species from adapting. Understanding the evolution process will assist you in making better choices regarding the future of the planet and its inhabitants.