The Academy's Evolution Site

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

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

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is used in many spiritual traditions and cultures as an emblem of unity and 무료에볼루션 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.

The first attempts at depicting the world of biology focused on categorizing organisms into distinct categories which were distinguished by physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms or small DNA fragments, significantly increased the variety that could be represented in the tree of life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity is still largely unrepresented3,4.

Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. Trees can be constructed using molecular techniques like the small-subunit ribosomal gene.

Despite the dramatic growth of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is particularly true of microorganisms that are difficult to cultivate and are usually only present in a single specimen5. Recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that haven't yet been isolated, or their diversity is not thoroughly understood6.

The expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if particular habitats require special protection. This information can be used in a variety of ways, from identifying the most effective remedies to fight diseases to enhancing crops. This information is also extremely useful for conservation efforts. It helps biologists discover areas that are likely to have species that are cryptic, which could perform important metabolic functions, and could be susceptible to changes caused by humans. While funding to protect biodiversity are essential, the best method to preserve 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, shows the connections between different groups of organisms. By using molecular information, morphological similarities and differences or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree which illustrates the evolutionary relationships between taxonomic groups. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that evolved from common ancestors. These shared traits can be either homologous or 에볼루션 바카라 analogous. Homologous traits share their underlying evolutionary path while analogous traits appear like they do, but don't have the same origins. Scientists arrange similar traits into a grouping referred to as a the clade. Every organism in a group share a characteristic, for example, amniotic egg production. They all came from an ancestor that had these eggs. A phylogenetic tree is then built by connecting the clades to identify the species which are the closest to each other.

Scientists utilize DNA or RNA molecular information to create a phylogenetic chart which is more precise and precise. This data is more precise than the morphological data and provides evidence of the evolution background of an organism or group. The use of molecular data lets researchers identify the number of organisms who share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships of organisms can be influenced by several factors including phenotypic plasticity, a type of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more like a species another, clouding the phylogenetic signal. However, this problem can be reduced by the use of techniques such as cladistics that include a mix of analogous and homologous features into the tree.

In addition, phylogenetics can help predict the time and pace of speciation. This information will assist conservation biologists in making decisions about 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 main idea behind evolution is that organisms change over time as a result of their interactions with their environment. A variety of theories about evolution have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that can be passed onto offspring.

In the 1930s and 1940s, concepts from various fields, including genetics, natural selection 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 바카라 에볼루션 how those variants change in time as a result of natural selection. This model, which incorporates mutations, genetic drift as well as gene flow and sexual selection, can be mathematically described mathematically.

Recent developments in the field of evolutionary developmental biology have demonstrated how variation can be introduced to a species by mutations, genetic drift and reshuffling of genes during sexual reproduction and migration between populations. These processes, as well as others, such as the directional selection process and the erosion of genes (changes in 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 phenotype (the expression of genotypes in individuals).

Students can better understand the concept of phylogeny through incorporating evolutionary thinking throughout all aspects of biology. In a study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution increased their understanding of evolution in the course of a college biology. For more information about how to teach evolution, see The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily: a Framework for Integrating Evolution into 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 moment; it is an ongoing process. Viruses reinvent themselves to avoid new drugs and 무료에볼루션 bacteria evolve to resist antibiotics. Animals adapt their behavior because of the changing environment. The changes that occur are often apparent.

It wasn't until the 1980s that biologists began realize that natural selection was also in play. The key is the fact that different traits can confer an individual rate of survival as well as reproduction, and may be passed on from one generation to another.

In the past, 에볼루션 무료 바카라 슬롯 (click here for info) if an allele - the genetic sequence that determines colour was found in a group of organisms that interbred, it could become more common than any other allele. In time, this could mean that the number of moths that have 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.

It is easier to see evolution when an organism, like bacteria, has a rapid generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples from each population are taken on a regular basis and more than 50,000 generations have now passed.

Lenski's research has revealed that mutations can alter the rate at which change occurs and the effectiveness at which a population reproduces. It also demonstrates that evolution is slow-moving, a fact that many are unable to accept.

Another example of microevolution is that mosquito genes that are resistant to pesticides are more prevalent in populations where insecticides are employed. This is due to the fact that the use of pesticides creates a pressure that favors individuals with resistant genotypes.

The speed of evolution taking place has led to a growing awareness of its significance in a world that is shaped by human activities, including climate change, 바카라 에볼루션 pollution, and the loss of habitats that hinder the species from adapting. Understanding evolution will assist you in making better choices about the future of our planet and its inhabitants.