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The Academy's Evolution Site

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

This site provides a range of resources for students, teachers, and general readers on evolution. It also includes important video clips 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 used in many cultures and spiritual beliefs as an emblem of unity and love. It also has practical applications, like providing a framework to understand the history of species and how they react to changes in the environment.

The first attempts at depicting the biological world focused on separating organisms into distinct categories that were identified by their physical and metabolic characteristics1. These methods, which relied on sampling of different parts of living organisms, or sequences of short DNA fragments, significantly expanded the diversity that could be represented in a tree of life2. These trees are mostly populated by eukaryotes, and the diversity of bacterial species is greatly underrepresented3,4.

Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. We can create trees using molecular techniques such as the small subunit ribosomal gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. This is particularly true of microorganisms, which can be difficult to cultivate and are typically only present in a single sample5. A recent study of all genomes that are known has produced a rough draft of the Tree of Life, including numerous bacteria and archaea that have not been isolated, and whose diversity is poorly understood6.

The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine whether specific habitats require special protection. This information can be utilized in a variety of ways, such as finding new drugs, battling diseases and improving crops. The information is also valuable for conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which could perform important metabolic functions and be vulnerable to human-induced change. While funds to safeguard biodiversity are vital but the most effective way to protect the world's biodiversity is for more people living in developing countries to be empowered with the necessary knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, shows the connections between groups of organisms. Scientists can construct a phylogenetic chart that shows the evolution of taxonomic categories using molecular information and morphological similarities or differences. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from an ancestor that shared traits. These shared traits can be either homologous or analogous. Homologous traits are the same in their evolutionary paths. Analogous traits might appear like they are but they don't share the same origins. Scientists put similar traits into a grouping called a clade. For instance, all the organisms in a clade have the characteristic of having amniotic eggs and evolved from a common ancestor that had 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 precise phylogenetic tree scientists make use of molecular data from DNA or RNA to establish the connections between organisms. This information is more precise than morphological data and provides evidence of the evolutionary history of an organism or group. The use of molecular data lets researchers determine the number of organisms that have the same ancestor and estimate their evolutionary age.

The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic plasticity an aspect of behavior that changes in response to unique environmental conditions. This can cause a trait to appear more resembling to one species than to another which can obscure the phylogenetic signal. However, this issue can be reduced by the use of techniques such as cladistics which combine analogous and homologous features into the tree.

Additionally, phylogenetics aids determine the duration and rate of speciation. This information can aid conservation biologists in making decisions about which species to protect from extinction. Ultimately, it is the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem.

Evolutionary Theory

The fundamental concept of evolution is that organisms acquire various characteristics over time as a result of their interactions with their environment. 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 needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or 에볼루션 슬롯바카라 - https://telegra.ph/Can-Evolution-Baccarat-Free-Ever-Be-The-King-Of-The-World-12-21, non-use of certain traits can result in changes that can be passed on to future generations.

In the 1930s and 1940s, theories from a variety of fields -- including natural selection, genetics, and particulate inheritance - came together to form the current evolutionary theory synthesis which explains how evolution is triggered by the variation of genes within a population, and how those variants change over time as a result of natural selection. This model, which incorporates genetic drift, mutations as well as gene flow and sexual selection is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have shown how variations can be introduced to a species by genetic drift, mutations and reshuffling of genes during sexual reproduction and migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can result in evolution, which is defined by change in the genome of the species over time, and the change in phenotype as time passes (the expression of that genotype in an individual).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking throughout all aspects of biology. In a recent study by Grunspan and co. It was found that teaching students about the evidence for evolution boosted their understanding of evolution during a college-level course in biology. For more information on how to teach about evolution, 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

Scientists have traditionally looked at evolution through the past, studying fossils, and comparing species. They also observe living organisms. Evolution isn't a flims event; it is an ongoing process. Bacteria mutate and resist antibiotics, viruses evolve and elude new medications, and animals adapt their behavior to the changing climate. The results are often apparent.

It wasn't until 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 from one generation to the next.

In the past, when one particular allele--the genetic sequence that defines color in a group of interbreeding species, it could quickly become more common than the other alleles. In time, this could mean that the number of black moths within a population could 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 rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from a single strain. The samples of each population have been taken frequently and more than 50,000 generations of E.coli have been observed to have passed.

Lenski's work has demonstrated that mutations can drastically alter the speed at the rate at which a population reproduces, and consequently, the rate at which it evolves. It also shows that evolution takes time, which is difficult for 에볼루션 바카라 무료 some to accept.

Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more common in populations where insecticides have been used. This is due to the fact that the use of pesticides creates a selective pressure that favors people who have resistant genotypes.

The rapidity of evolution has led to a greater awareness of its significance especially in a planet shaped largely by human activity. This includes pollution, climate change, 에볼루션 바카라 무료 (Petersson-Cormier-3.Technetbloggers.De) and habitat loss that hinders many species from adapting. Understanding evolution will help us make better decisions regarding the future of our planet as well as the lives of its inhabitants.