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The Academy's Evolution Site

Biology is one of the most important concepts in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it permeates all areas of scientific exploration.

This site provides a range of sources for students, teachers and general readers of evolution. It includes the most important video clips 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 is an emblem of love and unity across many cultures. It also has important practical applications, like providing a framework for understanding the evolution of species and how they respond to changing environmental conditions.

The earliest attempts to depict the world of biology focused on categorizing organisms into distinct categories which were distinguished by their physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms or on sequences of small DNA fragments, significantly expanded the diversity that could be represented in the tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

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

The Tree of Life has been significantly expanded by genome sequencing. However, there is still much diversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are usually present in a single sample5. Recent analysis of all genomes has produced a rough draft of the Tree of Life. This includes a wide range of archaea, bacteria, and other organisms that have not yet been identified or their diversity is not well understood6.

This expanded Tree of Life can be used to determine the diversity of a specific region and determine if particular habitats need special protection. The information is useful in a variety of ways, including finding new drugs, fighting diseases and improving the quality of crops. This information is also useful to conservation efforts. It can aid biologists in identifying areas that are likely to have cryptic species, which could have important metabolic functions and are susceptible to the effects of human activity. Although funding to protect biodiversity are crucial, ultimately the best way to protect the world's biodiversity is for more people in developing countries to be equipped with the knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) depicts the relationships between organisms. Scientists can build an phylogenetic chart which shows the evolution of taxonomic groups based on molecular data and 에볼루션 게이밍 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 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous traits are identical in their underlying evolutionary path while analogous traits appear similar, but do not share the same ancestors. Scientists put similar traits into a grouping known as a the clade. All organisms in a group have a common characteristic, like amniotic egg production. They all came from an ancestor 에볼루션 바카라 체험 무료 에볼루션 (his comment is here) that had these eggs. The clades are then connected to create a phylogenetic tree to determine which organisms have the closest relationship.

To create a more thorough and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the relationships among organisms. This information is more precise than morphological information and gives evidence of the evolutionary history of an individual or group. Molecular data allows researchers to determine the number of organisms that have the same ancestor and estimate their evolutionary age.

Phylogenetic relationships can be affected by a number of factors such as the phenotypic plasticity. This is a type behavior that changes due to unique environmental conditions. This can cause a trait to appear more similar to a species than to the other, obscuring the phylogenetic signals. This problem can be addressed by using cladistics, which is a a combination of homologous and analogous features in the tree.

Additionally, phylogenetics can aid in predicting the time and pace of speciation. This information can aid conservation biologists to make decisions about which species to protect from extinction. In the end, it's the conservation of phylogenetic variety which will create an ecosystem that is balanced and complete.

Evolutionary Theory

The main idea behind evolution is that organisms acquire distinct characteristics over time as a result of 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 develop according to its own needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can cause changes that are passed on to the next generation.

In the 1930s and 1940s, concepts from a variety of fields--including genetics, natural selection and particulate inheritance -- came together to create the modern synthesis of evolutionary theory that explains how evolution occurs through the variations of genes within a population and how these variants change in time due to natural selection. This model, which encompasses mutations, genetic drift in gene flow, and sexual selection, can be mathematically described.

Recent developments in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species through mutation, genetic drift, and reshuffling of genes in sexual reproduction, and also through migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of the genotype over time), can lead to evolution that is defined as change in the genome of the species over time and also the change in phenotype over time (the expression of that genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny and evolution. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence supporting evolution increased students' understanding of evolution in a college-level biology course. For more details on how to teach evolution, see The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Scientists have looked at evolution through the past, studying fossils, and 에볼루션 게이밍 comparing species. They also study living organisms. However, evolution isn't something that happened in the past, it's an ongoing process happening right now. Bacteria mutate and resist antibiotics, viruses evolve and escape new drugs and animals change their behavior to the changing environment. The resulting changes are often evident.

However, it wasn't until late 1980s that biologists realized that natural selection could be observed in action as well. The key is that different traits have 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 group of interbreeding species, it could rapidly become more common than the other alleles. Over time, that would mean the number of black moths within a particular population could rise. The same is true for 에볼루션코리아 many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to see evolutionary change when the species, like bacteria, has a rapid generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each population are taken every day, and over 500.000 generations have passed.

Lenski's work has demonstrated that a mutation can profoundly alter the rate at the rate at which a population reproduces, and consequently the rate at which it alters. It also demonstrates that evolution takes time, something that is hard for some to accept.

Another example of microevolution is that mosquito genes for resistance to pesticides appear more frequently in areas where insecticides are employed. This is because pesticides cause a selective pressure which favors those with resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance especially in a planet shaped largely by human activity. This includes climate change, pollution, and habitat loss that prevents many species from adapting. Understanding the evolution process can assist you in making better choices about the future of the planet and its inhabitants.