The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies have been for a long time involved in helping people who are interested in science understand the theory of evolution and 에볼루션 슬롯 how it permeates every area of scientific inquiry.

This site provides teachers, students 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 life. It is an emblem of love and unity across many cultures. It can be used in many practical ways in addition to providing a framework for understanding the history of species, and how they react to changing environmental conditions.

The first attempts at depicting the world of biology focused on the classification of organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, which relied on the sampling of different parts of living organisms or sequences of small DNA fragments, significantly increased the variety that could be included in a tree of life2. These trees are largely composed by eukaryotes and bacterial diversity is vastly underrepresented3,4.

Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Trees can be constructed using molecular methods, such as the small-subunit ribosomal gene.

The Tree of Life has been dramatically expanded through genome sequencing. However there is still a lot of biodiversity to be discovered. This is especially true of microorganisms, which can be difficult to cultivate and are typically only present in a single specimen5. Recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a wide range of bacteria, archaea and other organisms that haven't yet been isolated or whose diversity has not been well 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. The information can be used in a variety of ways, from identifying new remedies to fight diseases to improving crop yields. It is also valuable to conservation efforts. It can help biologists identify the areas most likely to contain cryptic species that could have important metabolic functions that may be at risk from anthropogenic change. Although funding to safeguard biodiversity are vital but the most effective way to preserve the world's biodiversity is for more people living in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny, also known as an evolutionary tree, shows the connections between groups of organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationship of taxonomic categories using molecular information and morphological similarities or differences. Phylogeny is essential in understanding biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and have evolved from an ancestor that shared traits. These shared traits can be homologous, or analogous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear like they do, but don't have the same origins. Scientists organize similar traits into a grouping called a the clade. For example, all of the species in a clade share the trait of having amniotic egg and evolved from a common ancestor who had these eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms that are most closely related to each other.

Scientists use DNA or RNA molecular information to build a phylogenetic chart which is more precise and 에볼루션 코리아 precise. This information is more precise than the morphological data and gives evidence of the evolutionary history of an organism or group. The analysis of molecular data can help researchers determine the number of species who share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, an aspect of behavior that alters in response to specific environmental conditions. This can cause a characteristic to appear more like a species another, obscuring the phylogenetic signal. However, this issue can be reduced by the use of methods such as cladistics which incorporate a combination of homologous and analogous features into the tree.

In addition, phylogenetics helps determine the duration and rate at which speciation occurs. This information can help conservation biologists decide which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution have been developed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop gradually according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that can be passed on to the offspring.

In the 1930s and 1940s, concepts from a variety of fields--including natural selection, 에볼루션 코리아 genetics, and particulate inheritance - came together to create the modern synthesis of evolutionary theory that explains how evolution happens through the variations of genes within a population and how those variants change over time as a result of natural selection. This model, called genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of current evolutionary biology, and can be mathematically explained.

Recent advances in the field of evolutionary developmental biology have demonstrated how variations can be introduced to a species by genetic drift, mutations or reshuffling of genes in sexual reproduction and migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution which is defined by changes in the genome of the species over time and 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 and evolution. In a recent study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution in a college-level course in biology. To learn more about how to teach about evolution, read The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally looked at evolution through the past--analyzing fossils and comparing species. They also observe living organisms. Evolution is not a distant event, 에볼루션 바카라사이트 but a process that continues today. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior because of a changing world. The results are often evident.

It wasn't until late 1980s that biologists began to realize that natural selection was at work. The key is the fact that different traits result in the ability to survive at different rates and reproduction, and can be passed down from one generation to another.

In the past, if a certain 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. As time passes, this could mean that the number of moths with black pigmentation in a group could 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 easier when a species has a fast generation turnover such as bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples of each are taken on a regular basis and more than 500.000 generations have passed.

Lenski's research has revealed that mutations can alter the rate at which change occurs and the rate at which a population reproduces. It also proves that evolution takes time--a fact that many find difficult to accept.

Another example of microevolution is the way mosquito genes that confer resistance to pesticides appear more frequently in areas where insecticides are employed. That's because the use of pesticides creates a selective pressure that favors those who have resistant genotypes.

The rapidity of evolution has led to an increasing appreciation of its importance especially in a planet which is largely shaped by human activities. This includes climate change, pollution, and 에볼루션 게이밍 habitat loss that prevents many species from adapting. Understanding evolution will aid you in making better decisions regarding the future of the planet and its inhabitants.