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The Academy's Evolution Site

Biology is one of the most central concepts in biology. The Academies are committed to helping those interested in the sciences understand evolution theory and how it is permeated in all areas of scientific research.

This site provides students, teachers and general readers with a variety of learning resources on evolution. It contains the most important video clips from NOVA and the 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 as well, such as providing a framework for understanding the evolution of species and how they react to changing environmental conditions.

Early attempts to describe the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, based on sampling of different parts of living organisms or small fragments of their DNA greatly increased the variety of organisms that could be represented in the tree of life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.

Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques enable us to create trees using sequenced markers like the small subunit ribosomal RNA gene.

The Tree of Life has been dramatically expanded through genome sequencing. However there is a lot of biodiversity to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are usually only represented in a single specimen5. Recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that have not yet been isolated or the diversity of which is not well understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine whether specific habitats require protection. The information is useful in many ways, 에볼루션, Wiki.pine64.Org, including finding new drugs, battling diseases and improving the quality of crops. This information is also extremely valuable for conservation efforts. It helps biologists determine the areas most likely to contain cryptic species with important metabolic functions that may be at risk of anthropogenic changes. Although funds to safeguard biodiversity are vital however, the most effective method to preserve 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 known as an evolutionary tree) illustrates the relationship between organisms. Scientists can create an phylogenetic chart which shows the evolutionary relationships between taxonomic groups using molecular data and morphological similarities or differences. Phylogeny is crucial in understanding evolution, biodiversity and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits can be analogous, or homologous. Homologous traits are similar in terms of their evolutionary path. Analogous traits could appear like they are however they do not have the same origins. Scientists arrange similar traits into a grouping called a the clade. For instance, all the species in a clade have the characteristic of having amniotic eggs and evolved from a common ancestor which had eggs. A phylogenetic tree can be built by connecting the clades to determine the organisms that are most closely related to one another.

To create a more thorough and accurate phylogenetic tree, scientists use molecular data from DNA or 에볼루션 RNA to identify the relationships between organisms. This data is more precise than morphological data and gives evidence of the evolutionary history of an organism or group. The analysis of molecular data can help researchers determine the number of organisms that share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationship can be affected by a number of factors that include the phenotypic plasticity. This is a type of behavior that changes due to unique environmental conditions. This can cause a characteristic to appear more similar to one species than to the other which can obscure the phylogenetic signal. However, this issue can be solved through the use of methods like cladistics, which include a mix of similar and homologous traits into the tree.

In addition, phylogenetics helps determine the duration and rate at which speciation takes place. This information can help conservation biologists make decisions about the species they should safeguard from extinction. Ultimately, it is the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms develop distinct characteristics over time based on their interactions with their surroundings. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could develop according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can cause changes that are passed on to the next generation.

In the 1930s & 1940s, theories from various areas, 에볼루션 무료체험 including genetics, natural selection and particulate inheritance, came together to form a contemporary evolutionary theory. This describes how evolution is triggered by the variations in genes within a population and how these variants change over time as a result of natural selection. This model, which is known as genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of current evolutionary biology, and can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have revealed how variations can be introduced to a species by genetic drift, mutations or reshuffling of genes in sexual reproduction and the movement between populations. These processes, as well as others such as the directional selection process and 에볼루션 바카라 사이트 the erosion of genes (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in individuals).

Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny and evolutionary. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution increased students' acceptance of evolution in a college-level biology course. For more information on how to teach evolution look up The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily: a Framework for 에볼루션 무료 바카라 Integrating Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally looked at evolution through the past--analyzing fossils and comparing species. They also observe living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process that is that is taking place right now. Bacteria transform and resist antibiotics, viruses evolve and elude new medications, and animals adapt their behavior to the changing environment. The changes that occur are often visible.

It wasn't until late 1980s that biologists began realize that natural selection was also in action. The key to this is that different traits result in an individual rate of survival as well as reproduction, and may be passed on from generation to generation.

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

The ability to observe evolutionary change is easier when a species has a rapid turnover of its generation like bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each population are taken regularly and more than 50,000 generations have now been observed.

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

Another example of microevolution is how mosquito genes that are resistant to pesticides are more prevalent in populations where insecticides are used. This is because the use of pesticides creates a selective pressure that favors people with resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance particularly in a world that is largely shaped by human activity. This includes climate change, pollution, and habitat loss that hinders many 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.