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The Academy's Evolution Site

Biological evolution is one of the most fundamental concepts in biology. The Academies are committed to helping those who are interested in science to comprehend the evolution theory and how it is incorporated in all areas of scientific research.

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

Tree of Life

The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is used in many spiritual traditions and cultures as an emblem of unity and love. It has numerous practical applications as well, including providing a framework for understanding the history of species and how they respond to changing environmental conditions.

Early attempts to describe the biological world were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which rely on the sampling of different parts of living organisms or on short DNA fragments, significantly expanded the diversity that could be included in the tree of life2. The trees are mostly composed by eukaryotes, and bacteria are largely underrepresented3,4.

Genetic techniques have greatly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods allow us to construct trees using sequenced markers such as the small subunit ribosomal RNA gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However, there is still much diversity to be discovered. This is especially the case for microorganisms which are difficult to cultivate and are usually present in a single sample5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including a large number of archaea and bacteria that are not isolated and whose diversity is poorly understood6.

The expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if certain habitats need special protection. The information is useful in many ways, including finding new drugs, fighting diseases and enhancing crops. It is also useful in conservation efforts. It helps biologists discover areas that are most likely to be home to species that are cryptic, which could perform important metabolic functions and are susceptible to human-induced change. While funding to protect biodiversity are essential, the best method to preserve the world's biodiversity is to empower more people in developing countries with the information they require to act locally and support conservation.

Phylogeny

A phylogeny, also called an evolutionary tree, shows the connections between various groups of organisms. Scientists can create an phylogenetic chart which shows the evolutionary relationship of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestors. These shared traits could be either analogous or homologous. Homologous traits are the same in terms of their evolutionary paths. Analogous traits could appear similar but they don't have the same ancestry. Scientists arrange similar traits into a grouping known as a Clade. For instance, all the organisms in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor that had eggs. A phylogenetic tree is then built by connecting the clades to determine the organisms that are most closely related to each other.

For 에볼루션게이밍 a more precise and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the connections between organisms. This information is more precise and provides evidence of the evolutionary history of an organism. The use of molecular data lets researchers identify the number of species who share the same ancestor and estimate their evolutionary age.

The phylogenetic relationship can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is a kind of behaviour that can change in response to particular environmental conditions. This can cause a characteristic to appear more resembling to one species than to the other, obscuring the phylogenetic signals. This problem can be addressed by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous traits in the tree.

In addition, phylogenetics can help predict the length and speed of speciation. This information will assist conservation biologists in making choices about which species to save from extinction. In the end, it's the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The main idea behind evolution is that organisms develop different features over time based on their interactions with their surroundings. Many theories of evolution have been developed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop gradually according to its 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 can cause changes that can be passed on to the offspring.

In the 1930s and 1940s, concepts from a variety of fields--including genetics, natural selection, and 에볼루션 무료 바카라 particulate inheritance -- came together to form the current evolutionary theory synthesis that explains how evolution occurs through the variation of genes within a population, and how those variations change over time as a result of 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 explained.

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

Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny as well as evolution. A recent study by Grunspan and 에볼루션 무료 바카라 colleagues, for example revealed that teaching students about the evidence supporting evolution increased students' understanding of evolution in a college biology course. To find out more about how to teach about evolution, look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution through looking back, 바카라 에볼루션 studying fossils, comparing species, and studying living organisms. But evolution isn't a thing that occurred in the past; it's an ongoing process, happening in the present. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior because of the changing environment. The resulting changes are often evident.

It wasn't until late-1980s that biologists realized that natural selection could be observed in action as well. The main reason is that different traits confer a different rate of survival and reproduction, and can be passed on 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 common than the other alleles. As time passes, this could mean that the number of moths that have black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

The ability to observe evolutionary change is much easier when a species has a fast generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. Samples of each population have been taken frequently and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's research has shown that a mutation can profoundly alter the rate at which a population reproduces--and so, the rate at which it evolves. It also shows that evolution takes time, which is hard for some to accept.

Another example of microevolution is the way mosquito genes that confer resistance to pesticides appear more frequently in populations in which insecticides are utilized. This is because pesticides cause a selective pressure which favors those with resistant genotypes.

The rapidity of evolution has led to a greater recognition of its importance, especially in a world which is largely shaped by human activities. This includes climate change, pollution, and habitat loss that hinders many species from adapting. Understanding evolution will aid you in making better decisions about the future of our planet and its inhabitants.