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The Academy's Evolution Site

The concept of biological evolution is among the most central concepts in biology. The Academies are involved in helping those who are interested in the sciences learn about the theory of evolution and how it is incorporated throughout all fields of scientific research.

This site provides students, teachers and general readers with a variety of learning resources about evolution. It has the most important video clips from NOVA and WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of life. It appears in many cultures and spiritual beliefs as a symbol of unity and love. It also has many practical applications, such as providing a framework for understanding the evolution of species and 에볼루션 블랙잭사이트 (https://Telegra.Ph) how they respond to changes in the environment.

The earliest attempts to depict the biological world focused on separating organisms into distinct categories that were distinguished by physical and metabolic characteristics1. These methods, based on the sampling of different parts of living organisms, or sequences of short DNA fragments, significantly expanded the diversity that could be included in a tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4.

Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Trees can be constructed using molecular techniques like the small-subunit ribosomal gene.

Despite the rapid growth of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is particularly true for microorganisms, which can be difficult to cultivate and are often only present in a single specimen5. Recent analysis of all genomes resulted in a rough draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that have not yet been identified or their diversity is not thoroughly understood6.

This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if specific habitats need special protection. This information can be used in a variety of ways, such as identifying new drugs, combating diseases and improving the quality of crops. This information is also extremely valuable for conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species that could have important metabolic functions that could be at risk of anthropogenic changes. While funds to protect biodiversity are important, the most effective method to protect the world's biodiversity is to equip more people in developing countries with the necessary knowledge to act locally and support conservation.

Phylogeny

A phylogeny, also known as an evolutionary tree, shows the relationships between various groups of organisms. Scientists can build a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological differences or similarities. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that evolved from common ancestral. These shared traits could be either homologous or analogous. Homologous traits are similar in terms of their evolutionary path. Analogous traits may look similar, but they do not share the same origins. Scientists put similar traits into a grouping known as a the clade. For instance, all the species in a clade share the characteristic of having amniotic egg and evolved from a common ancestor who had these eggs. The clades then join to form a phylogenetic branch that can determine the organisms with the closest relationship to.

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

The phylogenetic relationships of a species can be affected by a number of factors, including the phenotypic plasticity. This is a kind of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to a species than another which can obscure the phylogenetic signal. This problem can be addressed by using cladistics, which incorporates the combination of homologous and analogous features in the tree.

In addition, phylogenetics can help predict the time and pace of speciation. This information can aid conservation biologists to make decisions about the species they should safeguard from extinction. In the end, it is the preservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their environments. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can cause changes that are passed on to the next generation.

In the 1930s & 1940s, theories from various fields, such as natural selection, genetics & particulate inheritance, came together to form a contemporary evolutionary theory. This defines how evolution is triggered by the variation of genes in a population and how these variations change over time as a result of natural selection. This model, called genetic drift, mutation, gene flow and sexual selection, is a cornerstone of the current evolutionary biology and is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have shown how variation can be introduced to a species through genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of the genotype over time) can lead to evolution which is defined by change in the genome of the species over time, 에볼루션 바카라사이트 and also the change in phenotype over time (the expression of the genotype in an individual).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking into all areas of biology. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence supporting evolution increased students' understanding of evolution in a college biology course. For more information on how to teach evolution look up The Evolutionary Potency in all Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by looking back--analyzing fossils, 에볼루션게이밍 comparing species and observing living organisms. However, evolution isn't something that happened in the past, it's an ongoing process that is happening today. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior as a result of a changing world. The results are often apparent.

But it wasn't until the late 1980s that biologists realized that natural selection could be observed in action as well. The key is that various characteristics result in different rates of survival and reproduction (differential fitness) and are passed down 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 the other alleles. Over time, this would mean that the number of moths with black pigmentation may 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 rapid 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 been observed.

Lenski's research has revealed that a mutation can dramatically alter the rate at which a population reproduces--and so, the rate at which it changes. It also shows that evolution takes time, a fact that is difficult for some to accept.

Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more prevalent in areas that have used insecticides. That's because the use of pesticides causes a selective pressure that favors people with resistant genotypes.

The rapid pace of evolution taking place has led to a growing awareness of its significance in a world that is shaped by human activity--including climate change, pollution and the loss of habitats that prevent many species from adapting. Understanding the evolution process can help us make smarter choices about the future of our planet as well as the life of its inhabitants.