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The Academy's Evolution Site

Biology is one of the most fundamental 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 affects all areas of scientific exploration.

This site provides a range of resources for teachers, students as well as general readers about evolution. It includes key video clip 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 appears in many cultures and spiritual beliefs as a symbol of unity and love. It can be used in many practical ways in addition to providing a framework to understand the history of species and how they react to changes in environmental conditions.

Early approaches to depicting the biological world focused on the classification of organisms into distinct categories which were distinguished by physical and metabolic characteristics1. These methods, which relied on the sampling of various parts of living organisms or small DNA fragments, significantly increased the variety that could be included in the tree of life2. These trees are mostly populated by eukaryotes and bacterial diversity is vastly underrepresented3,4.

Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. We can construct trees by using molecular methods, such as the small-subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is a lot of biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and which are usually only present in a single sample5. Recent analysis of all genomes produced a rough draft of the Tree of Life. This includes a wide range of archaea, 에볼루션 바카라 카지노 사이트 (via hangoutshelp.net) bacteria, and other organisms that haven't yet been isolated, or their diversity is not well understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine if specific habitats require protection. This information can be used in many ways, including identifying new drugs, combating diseases and improving the quality of crops. The information is also incredibly valuable in conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species with important metabolic functions that could be vulnerable to anthropogenic change. While conservation funds are important, the best method to protect the biodiversity of the world is to equip the people of developing nations with the necessary knowledge to take action locally and encourage conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) depicts the relationships between organisms. Scientists can construct an phylogenetic chart which shows the evolutionary relationship of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is essential in understanding biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits could be analogous, or homologous. Homologous traits are identical in their underlying evolutionary path and analogous traits appear similar but do not have the same ancestors. Scientists arrange similar traits into a grouping called a Clade. All members of a clade have a common characteristic, for example, amniotic egg production. They all derived from an ancestor with these eggs. The clades are then connected to create a phylogenetic tree to identify organisms that have the closest relationship.

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

The phylogenetic relationships between organisms can be affected by a variety of factors, including phenotypic flexibility, an aspect of behavior that alters in response to unique environmental conditions. This can cause a trait to appear more similar to a species than another, obscuring the phylogenetic signals. However, this problem can be reduced by the use of methods such as cladistics which include a mix of similar and homologous traits into the tree.

Additionally, phylogenetics can aid in predicting the time and pace of speciation. This information can assist conservation biologists in making choices about which species to protect from disappearance. Ultimately, it is the preservation of phylogenetic diversity that will result in an ecologically balanced and complete ecosystem.

Evolutionary Theory

The central theme of evolution is that organisms acquire different features over time based on their interactions with their environments. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could develop according to its own requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can cause changes that are passed on to the next generation.

In the 1930s & 1940s, ideas from different fields, including genetics, natural selection and particulate inheritance, were brought together to create a modern synthesis of evolution theory. This explains how evolution is triggered by the variations in genes within the population, and how these variations change over time as a result of natural selection. This model, which is known as genetic drift or 에볼루션카지노사이트 (Http://120.Zsluoping.Cn) mutation, gene flow and sexual selection, is the foundation of modern evolutionary biology and can be mathematically explained.

Recent developments in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species via mutation, genetic drift, and reshuffling genes during sexual reproduction, and also by migration between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can result in evolution that is defined as changes in the genome of the species over time, and 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 and evolution. In a recent study by Grunspan et al., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution during a college-level course in biology. For more information on how to teach about evolution, 에볼루션 카지노 사이트 see The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution through looking back, studying fossils, comparing species and observing living organisms. Evolution is not a distant event, but an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, viruses reinvent themselves and are able to evade new medications and animals change their behavior in response to the changing climate. The resulting changes are often evident.

It wasn't until late 1980s that biologists realized that natural selection could be seen in action, as well. The main reason is that different traits can confer a different rate of survival as well as reproduction, and 에볼루션 카지노 사이트 may be passed on from one generation to the next.

In the past when one particular allele, the genetic sequence that defines color in a group of interbreeding species, it could rapidly become more common than other alleles. In time, this could mean that the number of moths sporting black pigmentation 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 particular species has a rapid generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from one strain. Samples from each population were taken regularly, and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's work has demonstrated 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 some people find difficult to accept.

Another example of microevolution is that mosquito genes for resistance to pesticides show up more often in areas where insecticides are used. This is due to pesticides causing a selective pressure which favors those who have resistant genotypes.

The speed at which evolution can take place has led to an increasing recognition of its importance in a world shaped by human activity--including climate change, pollution, and the loss of habitats that prevent many species from adapting. Understanding the evolution process can aid you in making better decisions about the future of the planet and its inhabitants.