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The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies are committed to helping those interested in the sciences learn about the theory of evolution and how it can be applied across all areas of scientific research.

This site provides students, teachers and general readers with a wide range of educational resources on evolution. It contains key video clips from NOVA and WGBH's science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, 에볼루션사이트 represents 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 in addition to providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.

Early approaches to depicting the biological world focused on the classification of organisms into distinct categories which had been distinguished by physical and metabolic characteristics1. These methods depend on the collection of various parts of organisms, or DNA fragments, have significantly increased the diversity of a Tree of Life2. However, these trees are largely composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4.

By avoiding the necessity for direct observation and experimentation, genetic techniques have enabled us to represent the Tree of Life in a more precise way. Trees can be constructed by using molecular methods like the small-subunit ribosomal gene.

Despite the rapid growth of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and which are usually only present in a single sample5. A recent analysis of all genomes that are known has produced a rough draft of the Tree of Life, including a large number of bacteria and archaea that are not isolated and their diversity is not fully understood6.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine whether specific habitats require special protection. The information can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing the quality of crops. The information is also valuable to conservation efforts. It can aid biologists in identifying areas most likely to have cryptic species, which may have important metabolic functions, 에볼루션 코리아 and could be susceptible to the effects of human activity. While funds to protect biodiversity are important, the best method to protect the world's biodiversity is to empower more people in developing nations with the knowledge they need to take action locally and encourage conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) shows the relationships between different organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic groups based on molecular data and morphological similarities or differences. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestors. These shared traits are either homologous or analogous. Homologous traits are similar in their evolutionary origins while analogous traits appear similar, but do not share the same ancestors. Scientists put similar traits into a grouping called a the clade. All organisms in a group have a common characteristic, like amniotic egg production. They all came from an ancestor who had these eggs. A phylogenetic tree is then constructed by connecting the clades to determine the organisms which are the closest to one another.

Scientists use DNA or RNA molecular information to construct a phylogenetic graph that is more accurate and detailed. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can use Molecular Data to determine the evolutionary age of organisms and identify the number of organisms that have an ancestor common to all.

The phylogenetic relationships of organisms are influenced by many factors, including phenotypic flexibility, a kind of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar in one species than other species, which can obscure the phylogenetic signal. This problem can be addressed by using cladistics, which incorporates an amalgamation of analogous and homologous features in the tree.

Additionally, phylogenetics aids predict the duration and rate at which speciation occurs. This information can help conservation biologists make decisions about the species they should safeguard from the threat of extinction. It is ultimately the preservation of phylogenetic diversity that will lead to an ecologically balanced and complete ecosystem.

Evolutionary Theory

The main idea behind evolution is that organisms develop different features over time due to their interactions with their environments. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would develop according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of certain traits can result in changes that can be passed on to future generations.

In the 1930s and 1940s, ideas from a variety of fields--including natural selection, genetics, and particulate inheritance -- came together to create the modern evolutionary theory synthesis that explains how evolution is triggered by the variation of genes within a population and how those variants change over time due to natural selection. This model, which is known as genetic drift or 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 demonstrated that variations can be introduced into a species by mutation, genetic drift, and reshuffling genes during sexual reproduction, 에볼루션 코리아 as well as through migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution which is defined by changes in the genome of the species over time and also by changes in phenotype as time passes (the expression of that genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny and evolutionary. A recent study conducted by Grunspan and colleagues, for example demonstrated that teaching about the evidence for evolution increased students' acceptance of evolution in a college biology course. For more information on how to teach about evolution, please read The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution by looking in the past, studying fossils, and comparing species. They also observe living organisms. Evolution is not a distant event; it is a process that continues today. Bacteria mutate and resist antibiotics, viruses reinvent themselves and elude new medications, and animals adapt their behavior in response to a changing planet. The changes that occur are often visible.

It wasn't until the 1980s when biologists began to realize that natural selection was also in action. The key to this is that different traits result in the ability to survive at different rates as well as reproduction, and may be passed down from one generation to the next.

In the past when one particular allele - the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it could rapidly become more common than all other alleles. As time passes, that could mean that the number of black moths in a particular population could rise. The same is true for many other characteristics--including morphology and 에볼루션 바카라 behavior--that vary among populations of organisms.

It is easier to track evolutionary change when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from one strain. The samples of each population have been collected regularly, and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's research has shown that mutations can drastically alter the efficiency with the rate at which a population reproduces, and consequently, the rate at which it changes. It also shows that evolution takes time, 에볼루션바카라 which is difficult for some to accept.

Another example of microevolution is that mosquito genes for resistance to pesticides are more prevalent in areas where insecticides are used. This is because pesticides cause an enticement that favors individuals who have resistant genotypes.

The speed of evolution taking place has led to a growing awareness of its significance in a world shaped by human activity, including climate changes, pollution and the loss of habitats which prevent the species from adapting. Understanding evolution can help us make better decisions regarding the future of our planet, and the lives of its inhabitants.