The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies are involved in helping those who are interested in science to learn about the theory of evolution and how it is incorporated throughout all fields of scientific research.

This site provides teachers, students and general readers with a wide range of educational 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 is an ancient symbol of the interconnectedness of life. It appears in many cultures and spiritual beliefs as a symbol of unity and love. It has many practical applications in addition to providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.

The first attempts to depict the world of biology were built on categorizing organisms based on their physical and metabolic characteristics. These methods rely on the collection of various parts of organisms, or fragments of DNA, have significantly increased the diversity of a tree of Life2. These trees are largely composed of eukaryotes, while bacteria are largely underrepresented3,4.

Genetic techniques have greatly broadened our ability to represent 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 greatly expanded thanks to genome sequencing. However there is still a lot of diversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are often only represented in a single sample5. Recent analysis of all genomes has 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 identified or the diversity of which is not fully understood6.

This expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if specific habitats require special protection. The information is useful in a variety of ways, including identifying new drugs, combating diseases and enhancing crops. It is also useful for conservation efforts. It helps biologists discover areas that are most likely to have cryptic species, which could have important metabolic functions and are susceptible to the effects of human activity. While funds to protect biodiversity are crucial, ultimately the best way to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between species. Using molecular data similarities and differences in morphology or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms witthe end, it's the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms acquire different features over time due to 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 a living thing would evolve according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or 에볼루션 사이트 absence of certain traits can result in changes that are passed on to the next generation.

In the 1930s and 1940s, concepts from various fields, 에볼루션 바카라사이트 including genetics, natural selection and particulate inheritance--came together to form the modern evolutionary theory synthesis which explains how evolution occurs through the variation of genes within a population and 에볼루션카지노사이트 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 is mathematically described mathematically.

Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species via mutation, genetic drift and reshuffling of genes in sexual reproduction, as well as through the movement of populations. These processes, along with others such as directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time and changes in phenotype (the expression of genotypes in individuals).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking into all areas of biology. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college biology class. For more information on how to teach evolution read The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have studied evolution by looking in the past--analyzing fossils and comparing species. They also study living organisms. Evolution is not a past moment; it is an ongoing process that continues to be observed today. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior because of the changing environment. The results are usually easy to see.

It wasn't until late 1980s that biologists realized that natural selection can be observed in action as well. The main reason is that different traits confer a different rate of survival and reproduction, and can be passed down from generation to generation.

In the past, when one particular allele--the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it could rapidly become more common than all other alleles. As time passes, this could mean that the number of moths sporting black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to track evolutionary change when the species, 에볼루션카지노사이트 like bacteria, 에볼루션 사이트 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 generations have been observed.

Lenski's research has shown that a mutation can dramatically alter the speed at which a population reproduces--and so, the rate at which it alters. It also shows that evolution takes time, something that is difficult for some to accept.

Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides have been used. This is due to the fact that the use of pesticides causes a selective pressure that favors those with resistant genotypes.

The rapidity of evolution has led to an increasing recognition of its importance, especially in a world that is largely shaped by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution will help us make better decisions regarding the future of our planet and the lives of its inhabitants.