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The Academy's Evolution Site

The concept of biological evolution is a fundamental 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 research.

This site provides a range of tools for students, teachers as well as general readers about evolution. It includes key video clip 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 seen in a variety of religions and cultures as a symbol of unity and love. It can be used in many practical ways in addition to providing a framework to understand the history of species, and how they react to changing environmental conditions.

The first attempts at depicting the biological world focused on separating organisms into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, which relied on sampling of different parts of living organisms or sequences of short DNA fragments, greatly increased the variety of organisms that could be represented in a tree of life2. However these trees are mainly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.

By avoiding the necessity for direct experimentation and observation, genetic techniques have made it possible to depict the Tree of Life in a more precise manner. Particularly, molecular methods allow us to build trees using sequenced markers, such as the small subunit ribosomal gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However there is a lot of biodiversity to be discovered. This is especially true for 에볼루션 코리아 microorganisms that are difficult to cultivate and which are usually only present in a single sample5. A recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a variety of bacteria, 에볼루션 룰렛 archaea and other organisms that haven't yet been identified or whose diversity has not been fully understood6.

The expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if particular habitats require special protection. The information can be used in a range of ways, from identifying new medicines to combating disease to enhancing crops. The information is also useful to conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species that could have significant metabolic functions that could be at risk from anthropogenic change. Although funds to safeguard biodiversity are vital however, the most effective method to ensure the preservation of biodiversity around the world is for more people living in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, reveals the relationships between various groups of organisms. Scientists can construct an phylogenetic chart which shows the evolutionary relationship of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny is essential in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar characteristics and have evolved from a common ancestor. These shared traits are either homologous or analogous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear like they do, but don't have the identical origins. Scientists arrange similar traits into a grouping known as a the clade. For instance, all of the organisms in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor which had these eggs. The clades are then connected to create a phylogenetic tree to determine which organisms have the closest relationship to.

For a more detailed and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the connections between organisms. This information is more precise and provides evidence of the evolution of an organism. Molecular data allows researchers to identify the number of organisms who share a common ancestor and to estimate their evolutionary age.

The phylogenetic relationship can be affected by a number of factors that include the phenomenon of phenotypicplasticity. This is a kind of behaviour that can change as a result of specific environmental conditions. This can cause a characteristic to appear more like a species another, obscuring the phylogenetic signal. This problem can be addressed by using cladistics, which is a a combination of analogous and homologous features in the tree.

Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information can assist conservation biologists in making choices about which species to protect from disappearance. Ultimately, it is the preservation of phylogenetic diversity which will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would evolve according to its individual needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of certain traits can result in changes that are passed on to the next generation.

In the 1930s & 1940s, ideas from different areas, including genetics, natural selection and particulate inheritance, were brought together to create a modern synthesis of evolution theory. This explains how evolution occurs by the variations in genes within the population and how these variants change over time as a result of natural selection. This model, called genetic drift mutation, gene flow and sexual selection, is the foundation of current evolutionary biology, and can be mathematically described.

Recent developments in the field of evolutionary developmental biology have revealed that variations can be introduced into a species through genetic drift, mutation, and 에볼루션 게이밍 reshuffling of genes during sexual reproduction, as well as through the movement of populations. These processes, along with others, such as directional selection and gene erosion (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in phenotype (the expression of genotypes within individuals).

Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence that supports evolution increased students' acceptance of evolution in a college-level biology class. For more details on how to teach evolution read The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species, and observing living organisms. However, evolution isn't something that occurred in the past, it's an ongoing process that is taking place in the present. Bacteria evolve and resist antibiotics, viruses evolve and escape new drugs, and animals adapt their behavior to the changing climate. The resulting changes are often easy to see.

It wasn't until late 1980s that biologists began realize that natural selection was also in action. The reason is that different traits confer different rates of survival and reproduction (differential fitness), and can be passed from one generation to the next.

In the past, if a certain allele - the genetic sequence that determines colour was present in a population of organisms that interbred, 에볼루션 사이트코리아, Wzgroupup.hkhz76.Badudns.cc, it could become more common than other allele. Over time, this would mean that the number of moths sporting black pigmentation in a group could increase. 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 an organism, like bacteria, has a high generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples from each population are taken regularly, and over 500.000 generations have been observed.

Lenski's work has demonstrated that a mutation can profoundly alter the efficiency with which a population reproduces and, consequently the rate at which it alters. It also shows that evolution is slow-moving, a fact that some people find hard to accept.

Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides are used. This is due to pesticides causing an enticement that favors individuals who have resistant genotypes.

The rapidity of evolution has led to an increasing appreciation of its importance, especially in a world that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding the evolution process can help you make better decisions regarding the future of the planet and its inhabitants.