The Academy's Evolution Site

Biology is a key concept in biology. The Academies are involved in helping those who are interested in science to comprehend the evolution theory and how it is permeated across all areas of scientific research.

This site provides students, teachers and general readers with a variety of learning resources on evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and unity in many cultures. It can be used in many practical ways as well, such as providing a framework to understand the history of species, and how they respond to changing environmental conditions.

Early approaches to depicting the biological world focused on the classification of species into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms, or sequences of small DNA fragments, greatly increased the variety of organisms that could be included in the tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.

By avoiding the need for direct experimentation and observation genetic techniques have made it possible to represent the Tree of Life in a more precise way. We can create trees using molecular techniques such as the small subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is still 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. A recent analysis of all genomes has produced an unfinished draft of a Tree of Life. This includes a large number of bacteria, archaea and 에볼루션 other organisms that have not yet been isolated, 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 need special protection. This information can be utilized in a variety of ways, from identifying the most effective medicines to combating disease to improving the quality of crops. This information is also extremely useful for conservation efforts. It can aid biologists in identifying areas that are most likely to be home to species that are cryptic, which could have important metabolic functions and be vulnerable to the effects of human activity. While conservation funds are important, the most effective method to protect the world's biodiversity is to empower more people in developing countries with the information they require to take action locally and encourage conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) shows the relationships between species. Scientists can create a phylogenetic chart that shows the evolution of taxonomic categories using molecular information and morphological differences or 에볼루션 바카라 무료체험 similarities. Phylogeny is essential in understanding biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestors. These shared traits are either analogous or homologous. Homologous traits share their evolutionary origins and analogous traits appear similar, but do not share the identical origins. Scientists combine similar traits into a grouping called a Clade. For example, all of the organisms in a clade share the characteristic of having amniotic egg and evolved from a common ancestor 에볼루션 무료체험 that had these eggs. The clades then join to create a phylogenetic tree to determine which organisms have the closest relationship to.

For a more detailed and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the relationships among organisms. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to determine the evolutionary age of living organisms and discover how many species have an ancestor common to all.

Phylogenetic relationships can be affected by a variety of factors that include the phenomenon of phenotypicplasticity. This is a type of behaviour that can change due to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another which can obscure the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous features in the tree.

Furthermore, phylogenetics may help predict the duration and rate of speciation. This information can assist conservation biologists in making choices about which species to save from extinction. In the end, it's the conservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire various characteristics over time as a result of their interactions with their environments. A variety of theories about evolution have been developed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its requirements as well as 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 causes changes that can be passed on to offspring.

In the 1930s and 1940s, concepts from various fields, including genetics, natural selection and particulate inheritance -- came together to form the current synthesis of evolutionary theory that explains how evolution occurs through the variations of genes within a population, and how those variants change over time due to natural selection. This model, which encompasses mutations, genetic drift in gene flow, and sexual selection can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species via mutation, 에볼루션 코리아 genetic drift and reshuffling of genes during sexual reproduction, as well as through the movement of populations. These processes, in conjunction with others, such as the directional selection process and the erosion of genes (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time and changes in phenotype (the expression of genotypes in an individual).

Students can better understand phylogeny by incorporating evolutionary thinking throughout all aspects of biology. In a study by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. For more information on how to teach evolution look up The Evolutionary Power of Biology in all Areas of Biology or 에볼루션 블랙잭 Thinking Evolutionarily as a Framework for Integrating 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 distant event; it is a process that continues today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior in the wake of a changing environment. The changes that result are often evident.

It wasn't until the 1980s when biologists began to realize that natural selection was also in play. The key is that different traits have different rates of survival and reproduction (differential fitness) and are transferred from one generation to the next.

In the past, if a certain allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could be more common than any other allele. As time passes, that could mean that the number of black moths in a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to observe evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from one strain. Samples of each population were taken regularly, and more than 500.000 generations of E.coli 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 demonstrates that evolution is slow-moving, a fact that some find difficult to accept.

Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more common in populations where insecticides have been used. That's because the use of pesticides creates a selective pressure that favors people with resistant genotypes.

The speed at which evolution takes place has led to a growing appreciation of its importance in a world shaped by human activities, including climate change, pollution, and the loss of habitats which prevent many species from adjusting. Understanding evolution can help us make better decisions about the future of our planet, and the life of its inhabitants.