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The Academy's Evolution Site

Biology is a key concept in biology. The Academies have been for a long time involved in helping people who are interested in science understand the concept of evolution and how it affects all areas of scientific exploration.

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

Tree of Life

The Tree of Life is an ancient symbol that represents the interconnectedness of all life. It is a symbol of love and unity across many cultures. It has many practical applications as well, such as providing a framework to understand the history of species and how they respond to changing environmental conditions.

Early attempts to represent the world of biology were founded on categorizing organisms on their metabolic and physical characteristics. These methods, based on sampling of different parts of living organisms or on sequences of small fragments of their DNA significantly increased the variety that could be included in the tree of life2. These trees are largely composed by eukaryotes, and bacteria are largely underrepresented3,4.

By avoiding the need for direct observation and experimentation genetic techniques have enabled us to depict the Tree of Life in a more precise manner. Particularly, molecular techniques allow us to construct trees using sequenced markers, such as the small subunit of ribosomal RNA gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is particularly true for microorganisms that are difficult to cultivate and which are usually only found in a single specimen5. A recent analysis of all genomes produced an unfinished draft of the Tree of Life. This includes a variety of archaea, bacteria, and other organisms that have not yet been identified or whose diversity has not been well understood6.

The expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine if specific habitats require protection. This information can be utilized in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crops. The information is also useful in conservation efforts. It can help biologists identify areas that are likely to have species that are cryptic, which could have important metabolic functions and are susceptible to the effects of human activity. While conservation funds are essential, the best method to protect the world's biodiversity is to empower the people of developing nations with the information they require to act locally and promote conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) depicts the relationships between species. Scientists can build a phylogenetic chart that shows the evolutionary relationships between taxonomic groups based on molecular data and morphological similarities or differences. Phylogeny is crucial in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestral. These shared traits can be either analogous or homologous. Homologous traits share their evolutionary origins and analogous traits appear like they do, but don't have the identical origins. Scientists combine similar traits into a grouping called a clade. For instance, all the organisms in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor which had eggs. A phylogenetic tree can be constructed by connecting the clades to determine the organisms who are the closest to one another.

Scientists utilize molecular DNA or RNA data to create a phylogenetic chart that is more accurate and detailed. This information is more precise than morphological information and provides evidence of the evolutionary history of an individual or 에볼루션 코리아 group. Researchers can use Molecular Data to calculate the evolutionary age of organisms and determine how many organisms share a common ancestor.

Phylogenetic relationships can be affected by a number of factors, including the phenotypic plasticity. This is a type behavior that changes as a result of specific environmental conditions. This can cause a trait to appear more like a species another, clouding the phylogenetic signal. This issue can be cured by using cladistics. This is a method that incorporates an amalgamation of analogous and homologous features in the tree.

In addition, phylogenetics helps predict the duration and rate of speciation. This information can assist conservation biologists in making decisions about which species to safeguard from the threat of extinction. In the end, it's the conservation of phylogenetic variety that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms change over time due to their interactions with their environment. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would evolve according to its individual requirements and 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 usage or non-use of certain traits can result in changes that are passed on to the next generation.

In the 1930s and 1940s, 무료 에볼루션 theories from a variety of fields -- including natural selection, genetics, and particulate inheritance -- came together to form the modern synthesis of evolutionary theory, which defines how evolution occurs through the variations of genes within a population, and 에볼루션 슬롯 how those variants change in time due to natural selection. This model, known as genetic drift or mutation, gene flow and sexual selection, is the foundation of current evolutionary biology, and is mathematically described.

Recent advances in the field of evolutionary developmental biology have demonstrated how variations can be introduced to a species by mutations, genetic drift and reshuffling of genes during sexual reproduction, and even migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of the 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 the genotype within the individual).

Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny and evolution. A recent study conducted by Grunspan and colleagues, for example revealed that teaching students about the evidence supporting evolution helped students accept the concept of evolution in a college-level biology course. To learn more about how to teach about evolution, please read The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of 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. Evolution isn't a flims event, but an ongoing process that continues to be observed today. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior because of a changing world. The results are often apparent.

However, it wasn't until late-1980s that biologists realized that natural selection could be observed in action as well. The key to this is that different traits confer a different rate of survival as well as reproduction, and may be passed down from one generation to the next.

In the past, when one particular allele--the genetic sequence that controls coloration - was present in a group of interbreeding species, it could quickly become more prevalent than all other alleles. As time passes, that could 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.

It is easier to observe evolution when the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from a single strain. Samples from each population were taken frequently and more than 500.000 generations of E.coli have passed.

Lenski's work has demonstrated that a mutation can dramatically alter the efficiency with which a population reproduces and, 무료 에볼루션; Full File, consequently the rate at which it alters. It also demonstrates that evolution takes time, a fact that is difficult for some to accept.

Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more prevalent in areas where insecticides are used. This is because the use of pesticides creates a pressure that favors individuals with resistant genotypes.

The speed at which evolution takes place has led to a growing awareness of its significance 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 evolution can help us make smarter decisions about the future of our planet, as well as the life of its inhabitants.