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The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies have been active for a long time in helping those interested in science understand the theory of evolution and how it permeates all areas of scientific exploration.

This site provides teachers, students and general readers with a variety of educational resources on evolution. It includes key video clips from NOVA and WGBH's science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that represents the interconnectedness of life. It is an emblem 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 evolution of species and how they react to changing environmental conditions.

Early attempts to describe the world of biology were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which rely on sampling of different parts of living organisms, or short fragments of their DNA greatly increased the variety of organisms that could be included in a tree of life2. These trees are mostly populated by eukaryotes, and the diversity of bacterial species is greatly underrepresented3,4.

Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. We can create trees using molecular methods, such as the small-subunit ribosomal gene.

Despite the rapid growth of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is especially relevant to microorganisms that are difficult to cultivate and are usually present in a single sample5. A recent study of all known genomes has produced a rough draft version of the Tree of Life, including many bacteria and archaea that have not been isolated, and whose diversity is poorly understood6.

This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if specific habitats need special protection. The information can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing the quality of the quality of crops. The information is also valuable for conservation efforts. It helps biologists determine the areas most likely to contain cryptic species with important metabolic functions that could be at risk of anthropogenic changes. While funding to protect biodiversity are essential, the best method to protect the biodiversity of the world is to equip more people in developing countries with the information they require to act locally and support conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) depicts the relationships between species. 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 relationship between taxonomic categories. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous characteristics are identical in terms of their evolutionary journey. Analogous traits could appear similar but they don't share the same origins. Scientists arrange similar traits into a grouping referred to as a clade. For instance, all of the species in a clade share the trait of having amniotic eggs. They evolved from a common ancestor that had eggs. The clades are then connected to form a phylogenetic branch to determine which organisms have the closest connection to each other.

For a more precise and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to identify the relationships between organisms. This information is more precise and provides evidence of the evolution history of an organism. Researchers can use Molecular Data to determine the age of evolution of organisms and determine how many species share a common ancestor.

The phylogenetic relationship can be affected by a variety of factors such as the phenotypic plasticity. This is a kind of behavior that changes in response to unique environmental conditions. This can make a trait appear more similar to one species than another and obscure the phylogenetic signals. This issue can be cured by using cladistics, which incorporates an amalgamation of analogous and homologous features in the tree.

Additionally, phylogenetics aids predict the duration and 에볼루션 룰렛 rate at which speciation occurs. This information can aid conservation biologists in making choices about which species to protect from extinction. In the end, it's the preservation of phylogenetic diversity that will result in an ecosystem that is complete and 에볼루션 바카라 무료체험 balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire different features over time as a result of their interactions with their environments. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could develop according to its own requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of traits can lead to changes that are passed on to the

In the 1930s and 1940s, concepts from a variety of fields -- including genetics, 에볼루션 바카라 무료체험 natural selection and particulate inheritance--came together to create the modern evolutionary theory synthesis which explains how evolution occurs through the variation of genes within a population, and how those variants change in time due to natural selection. This model, which is known as genetic drift or mutation, gene flow, 에볼루션코리아 and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically explained.

Recent developments in evolutionary developmental biology have demonstrated how variations can be introduced to a species through mutations, genetic drift and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as other ones like the directional selection process and 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 an individual).

Students can better understand phylogeny by incorporating evolutionary thinking in all areas of biology. A recent study by Grunspan and colleagues, for instance, showed that teaching about the evidence for evolution increased students' understanding of evolution in a college biology course. For more details on how to teach about evolution look up 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 through looking back in the past--analyzing fossils and comparing species. They also study living organisms. Evolution isn't a flims event; it is an ongoing process. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior because of a changing environment. The changes that occur are often evident.

But it wasn't until the late 1980s that biologists understood that natural selection can be seen in action, as well. The key is the fact that different traits can confer a different rate of survival and reproduction, and can be passed on from one generation to the next.

In the past, if one particular allele, the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it could quickly become more common than all other alleles. Over time, that would mean that the number of black moths within the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to observe evolutionary change when a species, such as bacteria, has a high generation turnover. 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 on a regular basis, and over fifty thousand generations have passed.

Lenski's research has revealed that mutations can drastically alter the rate at which a population reproduces--and so, the rate at which it evolves. It also shows that evolution takes time--a fact that many find hard to accept.

Another example of microevolution is the way mosquito genes that are resistant to pesticides are more prevalent in populations where insecticides are used. This is because pesticides cause an enticement that favors individuals who have resistant genotypes.

The rapidity of evolution has led to a growing awareness of its significance, especially in a world which is largely shaped by human activities. This includes climate change, pollution, 에볼루션 바카라 무료체험 and habitat loss, which prevents many species from adapting. Understanding the evolution process can help us make better choices about the future of our planet as well as the life of its inhabitants.