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The Academy's Evolution Site

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

This site offers a variety of tools for teachers, students, and general readers on evolution. It contains important video clips from NOVA and WGBH's science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is a symbol of love and unity in many cultures. It has numerous practical applications as well, 무료에볼루션 such as providing a framework for understanding the history of species, and how they respond to changes in environmental conditions.

Early attempts to describe the world of biology were built on categorizing organisms based on their physical and metabolic characteristics. These methods, based on sampling of different parts of living organisms, or sequences of short fragments of their DNA, significantly increased the variety that could be included in a tree of life2. However these trees are mainly made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.

By avoiding the need for direct experimentation and observation, genetic techniques have enabled us to depict the Tree of Life in a more precise way. Particularly, molecular methods allow us to construct trees using sequenced markers, such as the small subunit ribosomal gene.

Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is especially true of microorganisms that are difficult to cultivate and are usually only represented 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 are not isolated and their diversity is not fully understood6.

The expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if certain habitats need special protection. The information can be used in a range of ways, from identifying the most effective remedies to fight diseases to improving crops. It is also valuable to conservation efforts. It helps biologists discover areas that are likely to have species that are cryptic, which could perform important metabolic functions and be vulnerable to human-induced change. While conservation funds are important, the most effective method to protect the world's biodiversity is to empower more people in developing nations with the knowledge they need to act locally and promote conservation.

Phylogeny

A phylogeny, also known as an evolutionary tree, 에볼루션 바카라 무료 무료 바카라 에볼루션 (Sciencewiki.Science) shows the connections between different groups of organisms. Utilizing molecular data, morphological similarities and differences, or ontogeny (the process of the development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolution of taxonomic categories. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and evolved from an ancestor with common traits. These shared traits can be either homologous or analogous. Homologous traits are the same in terms of their evolutionary path. Analogous traits might appear like they are however they do not have the same ancestry. Scientists put similar traits into a grouping called a clade. Every organism in a group have a common trait, such as amniotic egg production. They all evolved from an ancestor with these eggs. The clades are then linked to form a phylogenetic branch that can identify organisms that have the closest connection to each other.

To create a more thorough and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to identify the connections between organisms. This information is more precise and provides evidence of the evolution of an organism. Molecular data allows researchers to determine the number of species that have a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships of a species can be affected by a number of factors that include the phenotypic plasticity. This is a type of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more resembling to one species than to the other and obscure the phylogenetic signals. This problem can be mitigated by using cladistics, which is a an amalgamation of homologous and analogous features in the tree.

Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information can aid conservation biologists to decide the species they should safeguard from extinction. In the end, it is the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme of evolution is that organisms acquire different features over time based on their interactions with their environment. Many scientists have developed theories of evolution, including 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 conceived 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 lead to changes that are passed on to the next generation.

In the 1930s and 1940s, 무료에볼루션 concepts from various fields, including natural selection, genetics & particulate inheritance, were brought together to form a modern evolutionary theory. This explains how evolution happens through the variation in genes within the 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 the foundation of current evolutionary biology, and is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have revealed that variations can be introduced into a species via genetic drift, mutation, and reshuffling of genes in sexual reproduction, and also through the movement of populations. These processes, along with others such as the directional selection process and the erosion of genes (changes in the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time, as well as changes in phenotype (the expression of genotypes in an individual).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking throughout all areas of biology. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence supporting evolution helped students accept the concept of evolution in a college-level biology course. For more information on how to teach about evolution, please 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

Scientists have looked at evolution through the past, analyzing fossils and comparing species. They also observe living organisms. Evolution is not a past event, but a process that continues today. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of the changing environment. The results are often visible.

It wasn't until late 1980s that biologists began to realize that natural selection was also in play. The key to this is that different traits can confer the ability to survive at different rates and reproduction, and they can be passed on from one generation to the next.

In the past, if an allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could be more common than any other allele. In time, this could mean that the number of moths with black pigmentation in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to see evolution when the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from one strain. Samples from 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 a mutation can profoundly alter the rate at which a population reproduces--and so, the rate at which it evolves. It also demonstrates that evolution takes time, which is difficult for some to accept.

Another example of microevolution is that mosquito genes for resistance to pesticides appear more frequently in areas in which insecticides are utilized. This is because the use of pesticides causes a selective pressure that favors those who have resistant genotypes.

The speed at which evolution takes place has led to an increasing recognition of its importance in a world shaped by human activity--including climate changes, pollution and 무료에볼루션 the loss of habitats that hinder many species from adjusting. Understanding evolution can help you make better decisions about the future of the planet and its inhabitants.