The Academy's Evolution Site

The concept of biological evolution is among the most important concepts in biology. The Academies have been active for a long time in helping those interested in science understand the concept of evolution and how it permeates all areas of scientific exploration.

This site provides teachers, students and general readers with a variety of learning resources about evolution. It contains key video clips from NOVA and 에볼루션 슬롯 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 religions and cultures as a symbol of unity and love. It also has important practical applications, such as providing a framework to understand the history of species and how they react to changes in environmental conditions.

Early approaches to depicting the biological world focused on separating organisms into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods, based on sampling of different parts of living organisms, or sequences of short fragments of their DNA, significantly expanded the diversity that could be represented in the tree of life2. However, these trees are largely comprised of eukaryotes, and bacterial diversity is still largely unrepresented3,4.

By avoiding the need for direct observation and experimentation genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. In particular, molecular methods allow us to construct trees by using sequenced markers such as the small subunit ribosomal RNA gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is particularly relevant to microorganisms that are difficult to cultivate and are usually present in a single sample5. A recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that haven't yet been isolated, or their diversity is not thoroughly understood6.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine whether specific habitats require protection. The information can be used in a range of ways, from identifying new medicines to combating disease to enhancing the quality of the quality of crops. It is also beneficial for conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species with potentially important metabolic functions that may be at risk of anthropogenic changes. While funding to protect biodiversity are essential, the best method to preserve the biodiversity of the world is to equip more people in developing countries with the information they require to take action locally and encourage conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between different organisms. Using molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. The role of phylogeny is crucial in understanding genetics, biodiversity and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits may be analogous or homologous. Homologous traits are similar in their evolutionary roots and analogous traits appear similar, but do not share the same origins. Scientists group similar traits into a grouping known as a clade. All organisms in a group share a characteristic, like amniotic egg production. They all evolved from an ancestor that had these eggs. A phylogenetic tree is then constructed by connecting clades to identify the species which are the closest to one another.

For a more detailed and accurate phylogenetic tree, scientists make use of molecular data from DNA or RNA to establish the relationships among organisms. This information is more precise and provides evidence of the evolution history of an organism. Molecular data allows researchers to determine the number of species who share a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, a kind of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than other species, which can obscure the phylogenetic signal. However, this problem can be cured by the use of methods such as cladistics that incorporate a combination of analogous and homologous features into the tree.

In addition, phylogenetics can aid in predicting the length and speed of speciation. This information can help conservation biologists decide which species they should protect from extinction. In the end, it's the conservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The fundamental concept of evolution is that organisms acquire distinct characteristics over time based on their interactions with their environments. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of certain traits can result in changes that are passed on to the

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

Recent advances in evolutionary developmental biology have shown how variations can be introduced to a species via genetic drift, mutations or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution which is defined by change in the genome of the species over time, and the change in phenotype over time (the expression of that genotype in an individual).

Students can better understand the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence for evolution increased students' acceptance of evolution in a college biology course. For more information on how to teach about evolution, please read 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 studied evolution by looking in the past, analyzing fossils and comparing species. They also study living organisms. But evolution isn't a thing that occurred in the past, it's an ongoing process that is happening right now. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior because of a changing world. The results are often evident.

It wasn't until the late 1980s that biologists began to realize that natural selection was also at work. The main reason is that different traits result in an individual rate of survival and reproduction, and can be passed down from one generation to another.

In the past, if a certain allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could become more prevalent than any other allele. As time passes, that could mean the number of black moths in a population could increase. The same is true for 에볼루션 블랙잭 many other characteristics--including morphology and behavior--that vary among populations of organisms.

Monitoring evolutionary changes in action is easier when a particular species has a rapid generation turnover, 에볼루션 코리아 as with bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each are taken regularly, and over 50,000 generations have now been observed.

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

Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas that have used insecticides. This is because the use of pesticides creates a pressure that favors people with resistant genotypes.

The speed of evolution taking place has led to an increasing recognition of its importance in a world shaped by human activity--including climate change, pollution and 에볼루션 슬롯게임 the loss of habitats that prevent many species from adjusting. Understanding evolution can help you make better decisions regarding the future of the planet and its inhabitants.