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The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies have been for a long time involved in helping those interested in science comprehend the theory of evolution and how it affects all areas of scientific exploration.

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

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It appears in many spiritual traditions and cultures as a symbol of unity and love. It can be used in many practical ways as well, including providing a framework to understand the history of species, and how they respond to changes in environmental conditions.

Early attempts to represent the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods, 에볼루션 바카라사이트 which rely on the sampling of different parts of living organisms or sequences of small fragments of their DNA significantly expanded the diversity that could be included in a tree of life2. However these trees are mainly made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4.

In avoiding the necessity of direct observation and experimentation genetic techniques have made it possible to represent the Tree of Life in a much more accurate way. Particularly, molecular methods allow us to build trees by using sequenced markers, such as the small subunit ribosomal RNA gene.

The Tree of Life has been dramatically expanded through genome sequencing. However there is a lot of diversity to be discovered. This is especially true of microorganisms, which can be difficult to cultivate and are usually only represented in a single specimen5. A recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a large number of archaea, bacteria, and other organisms that haven't yet been isolated, or their diversity is not fully understood6.

The expanded Tree of Life can be used to determine the diversity of a particular area and determine if certain habitats require special protection. The information can be used in a variety of ways, 에볼루션 사이트 from identifying new medicines to combating disease to improving the quality of crops. It is also valuable to conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species with important metabolic functions that could be vulnerable to anthropogenic change. While conservation funds are important, the best method to preserve the world's biodiversity is to equip more people in developing countries with the knowledge they need to act locally and support conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between species. By using molecular information similarities and differences in morphology or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree that illustrates the evolutionary relationships between taxonomic groups. Phylogeny is crucial 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 evolved from common ancestral. These shared traits can be analogous, or homologous. Homologous characteristics are identical in terms of their evolutionary path. Analogous traits could appear similar however they do not have the same origins. Scientists organize similar traits into a grouping known as a Clade. All organisms in a group share a characteristic, like amniotic egg production. They all evolved from an ancestor that had these eggs. A phylogenetic tree can be constructed by connecting the clades to determine the organisms that are most closely related to one another.

For a more precise and precise phylogenetic tree scientists use molecular data from DNA or RNA to determine the relationships among organisms. This information is more precise than morphological information and provides evidence of the evolutionary history of an individual or group. Researchers can utilize Molecular Data to calculate the age of evolution of organisms and identify how many organisms have a common ancestor.

The phylogenetic relationships between organisms are influenced by many factors including phenotypic plasticity, a type of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more similar to one species than another, obscuring the phylogenetic signal. However, this problem can be cured by the use of techniques like cladistics, which include a mix of homologous and analogous features into the tree.

Additionally, phylogenetics aids predict the duration and rate at which speciation occurs. This information can assist conservation biologists in making decisions about which species to safeguard from disappearance. In the end, it is the conservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept of evolution is that organisms acquire distinct characteristics over time based on 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 an organism would evolve according to its individual needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical, 에볼루션사이트 as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of certain traits can result in changes that are passed on to the next generation.

In the 1930s and 1940s, ideas from a variety of fields -- including natural selection, genetics, and particulate inheritance -- came together to form the modern evolutionary theory synthesis which explains how evolution is triggered by the variations of genes within a population, and how these variants change over time due to natural selection. This model, called genetic drift or 에볼루션 블랙잭 mutation, gene flow and sexual selection, is a key element of the current evolutionary biology and can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species by genetic drift, mutation, and reshuffling genes during sexual reproduction, as well as by migration between populations. These processes, as well as other ones like directional selection and gene erosion (changes in frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time, as well as changes in phenotype (the expression of genotypes in an individual).

Incorporating evolutionary thinking into all areas of biology education could increase students' understanding of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence that supports evolution helped students accept the concept of evolution in a college biology class. For more information on how to teach about evolution, read The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also observe living organisms. But evolution isn't a thing that happened in the past, it's an ongoing process that is taking place in the present. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of a changing environment. The changes that occur are often visible.

But it wasn't until the late 1980s that biologists realized that natural selection can be seen in action, as well. The reason is that different characteristics result in different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.

In the past, if one particular allele--the genetic sequence that defines color in a group of interbreeding organisms, it could quickly become more prevalent than other alleles. As time passes, that could mean the number of black moths within the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Monitoring evolutionary changes in action is easier when a particular species has a fast generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, 에볼루션 has studied twelve populations of E.coli that are descended from one strain. The samples of each population have been taken regularly, and more than 50,000 generations of E.coli have passed.

Lenski's research has revealed that a mutation can profoundly alter the speed at which a population reproduces--and so the rate at which it changes. It also proves that evolution takes time--a fact that many are unable to accept.

Another example of microevolution is how mosquito genes that confer resistance to pesticides appear more frequently in populations where insecticides are employed. This is because the use of pesticides causes a selective pressure that favors those with resistant genotypes.

The speed of evolution taking 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 many species from adjusting. Understanding the evolution process will help us make better choices about the future of our planet as well as the lives of its inhabitants.