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The Academy's Evolution Site

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

This site provides students, teachers and general readers with a variety of learning resources on evolution. It contains the most important video clips from NOVA and the 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 a symbol of unity and love. It has numerous practical applications in addition to providing a framework for understanding the history of species and how they react to changes in environmental conditions.

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

Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. In particular, molecular methods enable us to create trees by using sequenced markers such as the small subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are typically found in a single specimen5. A recent analysis of all genomes that are known has produced a rough draft version of the Tree of Life, including numerous archaea and bacteria that are not isolated and which are not well understood.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if certain habitats require protection. This information can be used in many ways, including finding new drugs, battling diseases and improving the quality of crops. This information is also extremely valuable to conservation efforts. It can help biologists identify areas most likely to have species that are cryptic, which could have important metabolic functions, and could be susceptible to the effects of human activity. Although funding to protect biodiversity are crucial, 에볼루션 게이밍 블랙잭 (cool training) ultimately the best way to protect the world's biodiversity is for more people living 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, reveals the relationships between different groups of organisms. Utilizing molecular data as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree that illustrates the evolutionary relationship between taxonomic categories. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms with similar traits and have evolved from an ancestor that shared traits. These shared traits could be either homologous or analogous. Homologous traits are similar in their evolutionary origins while analogous traits appear similar but do not have the identical origins. Scientists organize similar traits into a grouping referred to as a clade. Every organism in a group share a trait, such as amniotic egg production. They all derived from an ancestor that had these eggs. The clades are then connected to form a phylogenetic branch that can determine the organisms with the closest relationship.

Scientists utilize DNA or RNA molecular data to build a phylogenetic chart that is more precise and precise. This data is more precise than the morphological data and provides evidence of the evolution background of an organism or group. The use of molecular data lets researchers determine the number of species that share the same ancestor and estimate their evolutionary age.

The phylogenetic relationships between organisms can be affected by a variety of factors, including phenotypic plasticity an aspect of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar in one species than another, clouding the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates an amalgamation of analogous and homologous features in the tree.

Additionally, phylogenetics aids determine the duration and speed at which speciation takes place. This information can assist conservation biologists in deciding which species to save from disappearance. It is ultimately the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire distinct characteristics over time due to their interactions with their environment. Many scientists have proposed 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 requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of traits can cause changes that are passed on to the

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

Recent advances in the field of evolutionary developmental biology have revealed the ways in which variation can be introduced to a species through mutations, genetic drift and reshuffling of genes during sexual reproduction and migration between populations. These processes, as well as others such as directionally-selected selection and erosion of genes (changes in frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time, as well as changes in phenotype (the expression of genotypes in individuals).

Students can better understand the concept of phylogeny by using evolutionary thinking throughout all areas of biology. A recent study conducted by Grunspan and colleagues, for example revealed that teaching students about the evidence for evolution increased students' acceptance of evolution in a college-level biology course. To learn more about how to teach about evolution, please look up The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution through looking back--analyzing fossils, comparing species and observing living organisms. Evolution is not a distant event, but an ongoing process. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior as a result of the changing environment. The resulting changes are often evident.

It wasn't until the 1980s that biologists began to realize that natural selection was at work. The key is the fact that different traits can confer a different rate of survival and reproduction, and can be passed down 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 might rapidly become more common than all other alleles. In time, this could mean that the number of moths sporting black pigmentation in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to track evolutionary change when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, 에볼루션 코리아 룰렛 (Evolutionsite29755.Popup-blog.com) has tracked twelve populations of E.coli that descend from a single strain. Samples of each population have been collected frequently and more than 50,000 generations of E.coli have passed.

Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also demonstrates that evolution is slow-moving, a fact that many find hard to accept.

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

The speed at which evolution can take place has led to an increasing awareness of its significance in a world that is shaped by human activity, including climate change, pollution, and the loss of habitats which prevent the species from adapting. Understanding evolution will help us make better decisions regarding the future of our planet as well as the lives of its inhabitants.