The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies have long been involved in helping people who are interested in science understand 에볼루션 슬롯게임 the concept of evolution and how it affects all areas of scientific exploration.

This site provides students, teachers and general readers with a range of learning resources on evolution. It has key video clips from NOVA and the WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that represents the interconnectedness of life. It is seen in a variety of religions and cultures as a symbol of unity and love. It has many practical applications in addition to providing a framework for understanding the history of species, and how they respond to changes in environmental conditions.

Early attempts to represent the biological world were built on categorizing organisms based on their metabolic and physical characteristics. These methods rely on the collection of various parts of organisms or short DNA fragments have greatly increased the diversity of a tree of Life2. These trees are largely composed by eukaryotes and bacteria are largely underrepresented3,4.

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

Despite the rapid growth of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly the case for microorganisms which are difficult to cultivate and are usually found in one sample5. Recent analysis of all genomes has produced an unfinished draft of the Tree of Life. This includes a large number of archaea, bacteria, 에볼루션 블랙잭 and other organisms that have not yet been isolated or the diversity of which is not well understood6.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if certain habitats require special protection. The information can be used in a range of ways, from identifying new treatments to fight disease to improving crop yields. The information is also valuable for conservation efforts. It can help biologists identify areas that are most likely to be home to species that are cryptic, which could perform important metabolic functions, and could be susceptible to changes caused by humans. Although funds to protect biodiversity are crucial but the most effective way to preserve the world's biodiversity is for more people in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between species. Scientists can build a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic groups using molecular data and morphological differences or similarities. The role of phylogeny is crucial in understanding genetics, 에볼루션 게이밍 biodiversity and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and evolved from a common ancestor. These shared traits can be either analogous or homologous. Homologous traits are similar in their evolutionary path. Analogous traits may look like they are but they don't have the same ancestry. Scientists put similar traits into a grouping known as a Clade. For instance, all the organisms that make up a clade share the characteristic of having amniotic eggs and evolved from a common ancestor who had these eggs. The clades are then connected to create a phylogenetic tree to determine which organisms have the closest relationship to.

Scientists make use of molecular DNA or RNA data to create a phylogenetic chart which is more precise and detailed. This information is more precise and provides evidence of the evolution history of an organism. Researchers can use Molecular Data to estimate the evolutionary age of living organisms and discover how many species have the same ancestor.

The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, a kind of behavior that changes in response to unique environmental conditions. This can cause a trait to appear more similar to one species than another, clouding the phylogenetic signal. However, this problem can be solved through the use of techniques such as cladistics which include a mix of similar and homologous traits into the tree.

Furthermore, phylogenetics may help predict the length and speed of speciation. This information can help conservation biologists decide which species to protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem.

Evolutionary Theory

The central theme of evolution is that organisms develop distinct characteristics over time as a result of their interactions with their environments. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its individual requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of traits can cause changes that are passed on to the

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

Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species by mutation, genetic drift and reshuffling genes during sexual reproduction, and also through migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of a 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 in an individual).

Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence for evolution increased students' understanding of evolution in a college-level biology class. 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 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 moment; it is an ongoing process that continues to be observed today. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior in the wake of a changing world. The changes that result are often easy to see.

It wasn't until late 1980s that biologists realized that natural selection could be observed in action as well. The reason is that different characteristics result in different rates of survival and 에볼루션 카지노 사이트게이밍 [Ai Db link for more info] reproduction (differential fitness) and can be passed down from one generation to the next.

In the past, if one particular allele, the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it might quickly become more prevalent than all other alleles. In time, this could mean the number of black moths in a population 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 rapid generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from one strain. The samples of each population were taken regularly and more than 50,000 generations of E.coli have passed.

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

Another example of microevolution is how mosquito genes for resistance to pesticides are more prevalent in populations where insecticides are used. This is because the use of pesticides creates a pressure that favors people with resistant genotypes.

The rapid pace of evolution taking place has led to an increasing appreciation of its importance in a world that is shaped by human activity--including climate change, pollution, and the loss of habitats which prevent the species from adapting. Understanding the evolution process can assist you in making better choices about the future of the planet and its inhabitants.