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The Academy's Evolution Site

The concept of biological evolution is among the most central concepts in biology. The Academies have been for a long time involved in helping those interested in science understand the concept of evolution and how it permeates all areas of scientific research.

This site offers a variety of sources for teachers, students, and general readers on evolution. It has the most important 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 used in many cultures and spiritual beliefs as symbolizing unity and love. It also has practical uses, like providing a framework to understand the history of species and how they respond to changes in environmental conditions.

Early approaches to depicting the world of biology focused on the classification of organisms into distinct categories which had been identified by their physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms or on small DNA fragments, significantly increased the variety that could be represented in the tree of life2. The trees are mostly composed by eukaryotes, and bacteria are largely underrepresented3,4.

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

Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate and which are usually only present in a single sample5. A recent analysis of all known genomes has produced a rough draft version of the Tree of Life, including many bacteria and archaea that have not been isolated, and their diversity is not fully understood6.

This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine if specific habitats require special protection. This information can be utilized in a variety of ways, from identifying the most effective medicines to combating disease to enhancing the quality of crops. This information is also extremely valuable in conservation efforts. It can help biologists identify areas that are likely to have species that are cryptic, which could have important metabolic functions and are susceptible to human-induced change. While funding to protect biodiversity are important, the most effective method to protect the world's biodiversity is to empower more people in developing countries with the information they require to act locally and promote conservation.

Phylogeny

A phylogeny, also called an evolutionary tree, illustrates the connections between groups of organisms. Scientists can build an phylogenetic chart which shows the evolution of taxonomic groups using molecular data and morphological similarities or differences. The concept of phylogeny is fundamental to understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and evolved from an ancestor 에볼루션 바카라 with common traits. These shared traits are either homologous or analogous. Homologous traits are similar in terms of their evolutionary paths. Analogous traits could appear similar but they don't have the same origins. Scientists organize similar traits into a grouping referred to as a Clade. For instance, all the organisms that make up a clade share the trait of having amniotic eggs. They evolved from a common ancestor who had these eggs. A phylogenetic tree is built by connecting the clades to determine the organisms that are most closely related to each other.

To create a more thorough and accurate phylogenetic tree scientists use molecular data from DNA or RNA to establish the relationships among organisms. This information is more precise and gives evidence of the evolution of an organism. Researchers can use Molecular Data to calculate the age of evolution of organisms and determine how many species have an ancestor common to all.

The phylogenetic relationships between species can be influenced by several factors, including phenotypic plasticity a kind of behavior that alters in response to specific environmental conditions. This can cause a particular trait to appear more similar in one species than another, obscuring the phylogenetic signal. However, 에볼루션게이밍 (check over here) this problem can be cured by the use of methods such as cladistics which combine analogous and homologous features into the tree.

Additionally, phylogenetics can help determine the duration and 에볼루션 게이밍 바카라 (Recommended Website) speed at which speciation takes place. This information can help conservation biologists make decisions about which species to protect from the threat of extinction. In the end, it's the conservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire various characteristics over time based on their interactions with their environments. Several theories of evolutionary change have been proposed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that can be passed on to offspring.

In the 1930s & 1940s, concepts from various areas, including genetics, natural selection, and particulate inheritance, merged to form a modern evolutionary theory. This defines how evolution occurs by the variation in genes within a population and how these variations change with time due to natural selection. This model, 에볼루션 바카라사이트 슬롯게임 (opensourcebridge.Science) which incorporates mutations, genetic drift in gene flow, and sexual selection, can be mathematically described.

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

Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for instance, showed that teaching about the evidence for evolution helped students accept the concept of evolution in a college-level biology class. For more information about how to teach evolution read The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have looked at evolution through the past, analyzing fossils and comparing species. They also study living organisms. Evolution is not a past moment; it is a process that continues today. Bacteria evolve and resist antibiotics, viruses re-invent themselves and elude new medications, and animals adapt their behavior in response to the changing environment. The results are usually easy to see.

It wasn't until the late 1980s when biologists began to realize that natural selection was also in action. The key is the fact that different traits confer a different rate of survival and reproduction, and can be passed down from generation to generation.

In the past, if one particular allele - the genetic sequence that controls coloration - was present in a population of interbreeding organisms, it could quickly become more prevalent than the other alleles. In time, this could mean that the number of moths sporting 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.

Observing evolutionary change in action is easier when a species has a fast generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from a single strain. Samples from each population were taken regularly, and more than 500.000 generations of E.coli have passed.

Lenski's research has revealed that mutations can drastically alter the speed at the rate at which a population reproduces, and consequently, the rate at which it alters. It also demonstrates that evolution takes time, a fact that many find difficult to accept.

Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides are used. This is due to the fact that the use of pesticides causes a selective pressure that favors people with resistant genotypes.

The speed at which evolution can take place has led to an increasing awareness of its significance in a world shaped by human activity--including climate changes, pollution and the loss of habitats which prevent many species from adapting. Understanding evolution can help us make better decisions regarding the future of our planet as well as the life of its inhabitants.