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The Academy's Evolution Site

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

This site provides a range of tools for teachers, students, and general readers on evolution. It contains key video clips from NOVA and WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is an emblem of love and unity across many cultures. It has many practical applications in addition to providing a framework to understand the history of species and how they respond to changes in environmental conditions.

Early attempts to describe the biological world were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on the sampling of various parts of living organisms, or small fragments of their DNA, significantly increased the variety 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 represent the Tree of Life by circumventing the requirement for direct observation and experimentation. In particular, molecular methods enable us to create trees using sequenced markers such as the small subunit of ribosomal RNA gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of diversity to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are usually only represented in a single sample5. Recent analysis of all genomes resulted in an initial draft of the Tree of Life. This includes a variety of archaea, bacteria and other organisms that haven't 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 particular habitats require special protection. The information can be used in a variety of ways, from identifying the most effective treatments to fight disease to enhancing the quality of crop yields. The information is also beneficial for conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with potentially significant metabolic functions that could be at risk from anthropogenic change. While funding to protect biodiversity are important, the best method to protect the biodiversity of the world is to equip the people of developing nations with the information they require to act locally and support conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) illustrates the relationship between organisms. Scientists can build a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous characteristics are identical in terms of their evolutionary path. Analogous traits may look similar however they do not have the same origins. Scientists put similar traits into a grouping called a clade. All members of a clade have a common trait, such as amniotic egg production. They all evolved from an ancestor who had these eggs. The clades are then connected to create a phylogenetic tree to determine which organisms have the closest relationship to.

To create a more thorough and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the relationships among organisms. This information is more precise than the morphological data and gives evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to determine the age of evolution of organisms and identify how many organisms have an ancestor 에볼루션 바카라 common to all.

The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic plasticity a kind of behavior that alters in response to unique environmental conditions. This can make a trait appear more similar to one species than to the other, obscuring the phylogenetic signals. This issue can be cured by using cladistics, which incorporates the combination of homologous and analogous features in the tree.

Additionally, phylogenetics can help predict the duration and rate at which speciation occurs. This information can help conservation biologists decide which species to protect from extinction. In the end, it's the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem.

Evolutionary Theory

The central theme of evolution is that organisms develop various characteristics over time based on their interactions with their surroundings. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), 에볼루션 슬롯 (79bo.Cc) who believed that a living thing would develop according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern taxonomy system that is hierarchical, 에볼루션 바카라 (hellswan62.bravejournal.net) 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

In the 1930s & 1940s, ideas from different fields, including natural selection, genetics & particulate inheritance, came together to form a modern synthesis of evolution theory. This describes how evolution is triggered by the variations in genes within the population, and how these variants change with time due to natural selection. This model, which encompasses genetic drift, mutations as well as gene flow and sexual selection, can be mathematically described mathematically.

Recent discoveries in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species by mutation, genetic drift and reshuffling of genes during sexual reproduction, and also through migration 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 and also by changes in phenotype as time passes (the expression of that genotype within the individual).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all aspects of biology. In a study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution increased their acceptance of evolution during a college-level course in biology. For more information on how to teach about evolution, please see 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--analyzing fossils, comparing species, and observing living organisms. Evolution is not a distant event; it is a process that continues today. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior in the wake of a changing environment. The results are usually visible.

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

In the past when one particular allele, the genetic sequence that controls coloration - was present in a group of interbreeding species, it could quickly become more common than the other alleles. Over time, this would mean that the number of moths sporting black pigmentation could 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 easier when a particular species has a fast generation turnover, as with bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. The samples of each population have been taken regularly, and more than 50,000 generations of E.coli have been observed to have passed.

Lenski's research has revealed that mutations can alter the rate of change and the efficiency of a population's reproduction. It also demonstrates that evolution takes time, which is difficult for some to accept.

Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides have been used. This is because pesticides cause an exclusive pressure that favors those with resistant genotypes.

The rapid pace 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 changes, pollution and the loss of habitats that prevent the species from adapting. Understanding the evolution process will help you make better decisions about the future of our planet and its inhabitants.