The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies are committed to helping those who are interested in the sciences understand evolution theory and how it is permeated throughout all fields of scientific research.

This site provides a range of sources for teachers, students, and general readers on evolution. It has key video clips from NOVA and WGBH's science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is seen in a variety of religions and cultures as an emblem of unity and love. It also has important practical uses, like providing a framework to understand the evolution of species and how they react to changes in environmental conditions.

The first attempts at depicting the world of biology focused on the classification of organisms into distinct categories which were distinguished by physical and metabolic characteristics1. These methods depend on the sampling of different parts of organisms or short fragments of DNA have significantly increased the diversity of a Tree of Life2. However, these trees are largely composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

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 allow us to build trees using sequenced markers, such as the small subunit of ribosomal RNA gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However there is a lot of diversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are typically found in a single specimen5. A recent study of all known genomes has produced a rough draft of the Tree of Life, 에볼루션코리아 including numerous bacteria and archaea that are not isolated and whose diversity is poorly understood6.

The expanded Tree of Life is particularly useful in assessing the diversity of an area, 에볼루션 무료 바카라 assisting to determine if certain habitats require special protection. The information can be used in a variety of ways, from identifying new remedies to fight diseases to enhancing the quality of the quality of crops. This information is also useful in conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species that could have important metabolic functions that could be at risk of anthropogenic changes. While funds to protect biodiversity are important, the best method to protect the biodiversity of the world is to equip more people in developing countries with the knowledge they need to act locally and support conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between different organisms. Scientists can construct a phylogenetic chart that shows the evolutionary relationships between taxonomic categories using molecular indicting the time and pace of speciation. This information can help conservation biologists decide which species they should protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity that will create an ecologically balanced and complete ecosystem.

Evolutionary Theory

The main idea behind evolution is that organisms develop various characteristics over time based on their interactions with their surroundings. 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 proposed that a living organism develop gradually according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that could be passed on to the offspring.

In the 1930s and 1940s, 에볼루션 바카라 사이트 (menwiki.men) theories from a variety of fields--including genetics, natural selection, and particulate inheritance--came together to create the modern evolutionary theory, which defines how evolution is triggered by the variations of genes within a population and how those variants 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 evolutionary developmental biology have shown how variation can be introduced to a species by genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, in conjunction 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 as well as changes in the phenotype (the expression of genotypes within individuals).

Students can better understand the concept of phylogeny by using evolutionary thinking into all areas of biology. In a recent study conducted by Grunspan and co. It was found that teaching students about the evidence for evolution boosted their understanding of evolution in a college-level course in biology. For more information on how to teach about evolution, look up The Evolutionary Potential in 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, studying fossils, and comparing species. They also observe living organisms. Evolution is not a past moment; it is an ongoing process. Bacteria mutate and resist antibiotics, viruses re-invent themselves and elude new medications and animals change their behavior to the changing climate. The changes that occur are often apparent.

However, it wasn't until late-1980s that biologists realized that natural selection can be observed in action as well. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and are transferred from one generation to the next.

In the past, when one particular allele--the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it could rapidly become more common than other alleles. As time passes, this could mean that the number of moths with 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.

Observing evolutionary change in action is easier when a species has a rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from one strain. Samples of each population were taken regularly, and more than 50,000 generations of E.coli have been observed to have passed.

Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the effectiveness of a population's reproduction. It also demonstrates that evolution takes time, a fact that is difficult for some to accept.

Another example of microevolution is that mosquito genes that are resistant to pesticides appear more frequently in areas where insecticides are used. That's because the use of pesticides creates a selective pressure that favors people who have resistant genotypes.

The speed at which evolution takes place has led to a growing appreciation of its importance in a world that is shaped by human activity--including climate change, pollution, and the loss of habitats that prevent the species from adapting. Understanding the evolution process can help us make smarter decisions regarding the future of our planet, as well as the lives of its inhabitants.