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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 science learn about the theory of evolution and how it is permeated throughout all fields of scientific research.

This site offers a variety of tools for students, teachers as well as general readers about evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that represents the interconnectedness of life. It is seen in a variety of religions and cultures as a symbol of unity and love. It also has practical uses, 에볼루션코리아 like providing a framework to understand the evolution of species and how they respond to changes in environmental conditions.

Early attempts to represent the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods rely on the sampling of different parts of organisms or short DNA fragments have greatly increased the diversity of a tree of Life2. The trees are mostly composed of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have enabled us to depict the Tree of Life in a more precise way. We can create trees by using molecular methods such as the small subunit ribosomal gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true of microorganisms that are difficult to cultivate and are usually only present in a single specimen5. A recent study of all genomes that are known has produced a rough draft of the Tree of Life, including a large number of archaea and bacteria that have not been 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 specific habitats require protection. This information can be used in a variety of ways, including identifying new drugs, combating diseases and enhancing crops. The information is also beneficial in conservation efforts. It can help biologists identify the areas most likely to contain cryptic species with potentially important metabolic functions that may be at risk of anthropogenic changes. While funding to protect biodiversity are important, the most effective method to preserve the world's biodiversity is to equip the people of developing nations with the necessary knowledge to act locally and promote conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) illustrates the relationship between organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationship of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is crucial in understanding biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from a common ancestor. These shared traits could be analogous or homologous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear similar but do not have the same origins. Scientists arrange similar traits into a grouping known as a the clade. For example, all of the organisms that make up a clade share the trait of having amniotic eggs and evolved from a common ancestor which had these eggs. The clades are then linked to form a phylogenetic branch to determine the organisms with the closest relationship to.

For a more precise and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the relationships among organisms. This information is more precise and gives evidence of the evolutionary history of an organism. The use of molecular data lets researchers determine the number of species that have a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships between species are influenced by many factors including phenotypic plasticity, a type of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to a species than to the other which can obscure the phylogenetic signal. However, this problem can be cured by the use of methods such as cladistics which include a mix of similar and homologous traits into the tree.

Additionally, phylogenetics aids determine the duration and rate at which speciation occurs. This information will assist conservation biologists in making decisions about which species to safeguard from extinction. In the end, it is the conservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms acquire different features over time as a result of their interactions with their environment. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical system of taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of traits can lead to changes that are passed on to the next generation.

In the 1930s & 1940s, concepts from various areas, including genetics, natural selection and particulate inheritance, came together to form a contemporary theorizing of evolution. This explains how evolution occurs by the variation of genes in the population, and how these variations change with time due to natural selection. This model, called genetic drift or 에볼루션코리아 [Get More] mutation, gene flow, and sexual selection, is the foundation of the current evolutionary biology and 무료 에볼루션 can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species through mutation, genetic drift, and reshuffling of genes in sexual reproduction, and also through the movement of populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time) can result in evolution, which is defined by changes in the genome of the species over time, and also the change in phenotype over time (the expression of the genotype in an individual).

Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny and evolutionary. In a study by Grunspan et al., it was shown that teaching students about the evidence for 에볼루션 사이트 evolution boosted their understanding of evolution during an undergraduate biology course. To find out more about how to teach about evolution, look up The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species and studying living organisms. Evolution is not a past event; it is a process that continues today. Viruses reinvent themselves to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior in the wake of a changing world. The changes that result are often visible.

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

In the past when one particular allele, the genetic sequence that defines color in a population of interbreeding organisms, it could rapidly become more common than all other alleles. Over time, this would mean that the number of moths sporting black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Observing evolutionary change in action is easier when a particular species has a fast generation turnover like bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples of each population are taken every day, and over 50,000 generations have now passed.

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

Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more prevalent in populations where insecticides have been used. That's because the use of pesticides creates a selective pressure that favors those who have resistant genotypes.

The rapid pace of evolution taking place has led to an increasing recognition of its importance in a world that is shaped by human activity--including climate change, pollution and the loss of habitats which prevent many species from adapting. Understanding evolution can help you make better decisions about the future of our planet and its inhabitants.