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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 the sciences learn about the theory of evolution and 에볼루션 코리아 (over here) how it is permeated in all areas of scientific research.

This site provides students, teachers and general readers with a variety of learning resources on evolution. It contains key 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 all life. It is a symbol of love and unity across many cultures. It can be used in many practical ways in addition to providing a framework for understanding the evolution of species and how they respond to changing environmental conditions.

The first attempts to depict the biological world were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which rely on sampling of different parts of living organisms, or small fragments of their DNA, significantly increased the variety that could be represented in the tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity is not represented in a large way3,4.

Genetic techniques have greatly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to construct trees by using sequenced markers, such as the small subunit of ribosomal RNA gene.

Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are usually present in a single sample5. A recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a variety of archaea, bacteria and other organisms that haven't yet been isolated, or the diversity of which is not well understood6.

This expanded Tree of Life can be used to evaluate the biodiversity of a specific area and 에볼루션 바카라 무료체험 determine if certain habitats require special protection. This information can be utilized in a variety of ways, from identifying the most effective treatments to fight disease to enhancing crops. This information is also extremely beneficial in conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species that could have important metabolic functions that may be at risk of anthropogenic changes. Although funding to safeguard biodiversity are vital, ultimately the best way to ensure the preservation of biodiversity around the world is for more people living in developing countries to be equipped with the knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between organisms. Using molecular data similarities and differences in morphology 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 essential in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits could be analogous or homologous. Homologous traits are similar in their evolutionary origins, 에볼루션 카지노 while analogous traits look like they do, but don't have the same ancestors. Scientists group similar traits into a grouping called a Clade. For instance, all of the organisms in a clade share the trait of having amniotic eggs. They evolved from a common ancestor that had eggs. A phylogenetic tree is constructed by connecting clades to identify the species who are the closest to each other.

To create a more thorough and accurate phylogenetic tree scientists use molecular data from DNA or RNA to identify the connections between organisms. This information is more precise than the morphological data and provides evidence of the evolution history of an individual or group. The use of molecular data lets researchers determine the number of species that share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships between organisms are influenced by many factors, including phenotypic plasticity an aspect of behavior 에볼루션 코리아 that changes in response to specific environmental conditions. This can cause a trait to appear more similar to one species than to another which can obscure the phylogenetic signal. This problem can be addressed by using cladistics, which incorporates an amalgamation of homologous and analogous traits in the tree.

Additionally, phylogenetics aids determine the duration and rate at which speciation takes place. This information will assist conservation biologists in making decisions about which species to save from the threat of extinction. In the end, it is the conservation of phylogenetic variety which will create an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme in evolution is that organisms alter over time because of their interactions with their environment. Several theories of evolutionary change have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that can be passed on to offspring.

In the 1930s and 1940s, theories from various fields, such as natural selection, genetics & particulate inheritance, were brought together to form a contemporary synthesis of evolution theory. This describes how evolution is triggered by the variation of genes in the population and how these variations alter over time due to natural selection. This model, which is known as genetic drift mutation, gene flow and sexual selection, is the foundation of the current evolutionary biology and can be mathematically described.

Recent developments in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species through mutation, genetic drift and reshuffling of genes during sexual reproduction, and also by migration between populations. These processes, 에볼루션 코리아 along with other ones like directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in an individual).

Incorporating evolutionary thinking into all areas of biology education could increase students' understanding of phylogeny as well as evolution. In a recent study by Grunspan et al. It was demonstrated that teaching students about the evidence for evolution boosted their acceptance of evolution during an undergraduate biology course. For more information on how to teach about evolution, see The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by looking back--analyzing fossils, comparing species, and studying living organisms. Evolution is not a distant moment; it is a process that continues today. Bacteria transform and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals alter their behavior to the changing environment. The changes that result are often evident.

However, it wasn't until late 1980s that biologists understood that natural selection could be seen in action, as well. The key to this is that different traits confer the ability to survive at different rates and reproduction, and can be passed down from generation to generation.

In the past, when one particular allele - the genetic sequence that determines coloration--appeared 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 moths that have black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Monitoring evolutionary changes in action is much easier when a species has a fast generation turnover 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 regularly, 바카라 에볼루션 and more than 50,000 generations of E.coli have passed.

Lenski's research has revealed that a mutation can profoundly alter the speed at the rate at which a population reproduces, and consequently, the rate at which it alters. It also proves that evolution is slow-moving, a fact that many find hard to accept.

Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more common in populations that have used insecticides. This is because the use of pesticides creates a pressure that favors individuals with resistant genotypes.

The speed at which evolution takes place has led to an increasing awareness of its significance in a world shaped by human activity--including climate change, pollution and the loss of habitats that hinder the species from adapting. Understanding evolution will help you make better decisions about the future of our planet and its inhabitants.