The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies are committed to helping those interested in science understand evolution theory and how it is incorporated in all areas of scientific research.

This site provides teachers, students and general readers with a wide range of learning resources on evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is a symbol of love and unity across many cultures. It has many practical applications in addition to providing a framework for understanding the history of species and how they react to changes in environmental conditions.

Early attempts to represent the world of biology were based on categorizing organisms based on their metabolic and physical characteristics. These methods, based on the sampling of various parts of living organisms or on small DNA fragments, greatly increased the variety of organisms that could be represented 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 depict the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular techniques allow us to construct trees using sequenced markers like the small subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of diversity to be discovered. This is particularly the case for microorganisms which are difficult to cultivate and which are usually only present in a single sample5. A recent analysis of all genomes known to date has produced a rough draft version of the Tree of Life, including a large number of archaea and 에볼루션 슬롯게임 bacteria that have not been isolated, and their diversity is not fully understood6.

The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if certain habitats require special protection. This information can be utilized in many ways, including identifying new drugs, combating diseases and improving the quality of crops. The information is also useful for conservation efforts. It helps biologists discover areas that are most likely to be home to cryptic species, which could have important metabolic functions, and could be susceptible to changes caused by humans. While funds to protect biodiversity are essential however, the most effective method to protect the world's biodiversity is for more people 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 connections between different groups of organisms. Scientists can construct an phylogenetic chart which shows the evolutionary relationships between taxonomic gro/>Additionally, phylogenetics can help determine the duration and rate of speciation. This information will assist conservation biologists in deciding which species to safeguard from extinction. Ultimately, it is the preservation of phylogenetic diversity which will create a complete and balanced ecosystem.

Evolutionary Theory

The fundamental concept 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 wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, 바카라 에볼루션 as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that can be passed on to offspring.

In the 1930s and 1940s, ideas from various fields, including genetics, natural selection, and particulate inheritance--came together to form the modern synthesis of evolutionary theory that explains how evolution happens through the variation of genes within a population, and how those variations change in time due to natural selection. This model, called genetic drift mutation, 에볼루션 바카라 gene flow and sexual selection, is a cornerstone of modern evolutionary biology and is mathematically described.

Recent developments in the field of evolutionary developmental biology have shown that variation can be introduced into a species through genetic drift, mutation, and reshuffling of genes during sexual reproduction, and also by migration between populations. These processes, in conjunction with others, such as directional selection and gene erosion (changes in 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 within individuals).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking into all aspects of biology. In a recent study by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution during the course of a college biology. For more details on how to teach about evolution look up The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also observe living organisms. Evolution is not a distant moment; it is an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, 에볼루션사이트 viruses re-invent themselves and escape new drugs, 에볼루션사이트 and animals adapt their behavior to a changing planet. The changes that result are often apparent.

It wasn't until late 1980s when biologists began to realize that natural selection was at work. The reason is that different traits confer different rates of survival and 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 defines color in a group of interbreeding organisms, it could quickly become more prevalent than other alleles. In time, this could mean that the number of moths that have black pigmentation in a group could increase. The same is true for 에볼루션 무료 바카라 many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to track evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples of each population are taken every day and over fifty thousand 에볼루션사이트 generations have passed.

Lenski's work has demonstrated that mutations can drastically alter the rate at which a population reproduces--and so, the rate at which it changes. It also shows that evolution is slow-moving, a fact that many are unable to accept.

Another example of microevolution is how mosquito genes for resistance to pesticides are more prevalent in areas in which insecticides are utilized. This is because the use of pesticides creates a pressure that favors those who have resistant genotypes.

The rapidity of evolution has led to a greater appreciation of its importance especially in a planet which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution will help us make better choices about the future of our planet as well as the lives of its inhabitants.