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The Academy's Evolution Site

Biology is a key concept in biology. The Academies have long been involved in helping people who are interested in science understand the theory of evolution and how it permeates all areas of scientific research.

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

Tree of Life

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

Early attempts to describe the world of biology were built on categorizing organisms based on their physical and metabolic characteristics. These methods rely on the collection of various parts of organisms or fragments of DNA, have greatly increased the diversity of a tree of Life2. However these trees are mainly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.

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

The Tree of Life has been greatly expanded thanks to genome sequencing. However, there is still much biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are often only present in a single specimen5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including a large number of archaea and bacteria that have not been isolated and whose diversity is poorly understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine whether specific habitats require protection. This information can be used in many ways, including identifying new drugs, combating diseases and improving the quality of crops. The information is also incredibly beneficial in conservation efforts. It can help biologists identify areas most likely to have species that are cryptic, 에볼루션 코리아 which could perform important metabolic functions and are susceptible to the effects of human activity. While funds to protect biodiversity are important, the best way to conserve the world's biodiversity is to empower more people in developing countries with the knowledge they need to take action locally and encourage conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) illustrates the relationship between different organisms. By using molecular information as well as morphological similarities and distinctions, or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree that illustrates the evolutionary relationship between taxonomic groups. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar traits and evolved from an ancestor with common traits. These shared traits could be homologous, or analogous. Homologous traits share their evolutionary roots, while analogous traits look like they do, but don't have the identical origins. Scientists combine similar traits into a grouping called a Clade. All members of a clade have a common characteristic, for example, amniotic egg production. They all came from an ancestor who had these eggs. A phylogenetic tree is then built by connecting the clades to identify the organisms who are the closest to each other.

Scientists use DNA or RNA molecular information to create a phylogenetic chart which is more precise and detailed. This information is more precise than the morphological data and gives evidence of the evolutionary background of an organism or group. Molecular data allows researchers to identify the number of species that have a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships of a species can be affected by a number of factors that include the phenotypic plasticity. This is a type behavior that alters in response to specific environmental conditions. This can cause a trait to appear more like a species another, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which incorporates the combination of analogous and homologous features in the tree.

In addition, phylogenetics can help predict the length and speed of speciation. This information can aid conservation biologists to decide 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 balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire different features over time due to their interactions with their environments. Several theories of evolutionary change have been developed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its 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, theories from various fields, such as natural selection, genetics & particulate inheritance, came together to create a modern theorizing of evolution. This describes how evolution occurs by the variation in genes within the population and how these variants change with time due to natural selection. This model, which includes genetic drift, mutations as well as gene flow and sexual selection is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species by genetic drift, mutations and reshuffling of genes during sexual reproduction and migration between populations. These processes, along with others such as the directional selection process and the erosion of genes (changes in frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time as well as changes in phenotype (the expression of genotypes within individuals).

Students can better understand the concept of phylogeny through incorporating evolutionary thinking throughout all aspects of biology. In a recent study by Grunspan et al. It was found that teaching students about the evidence for evolution increased their understanding of evolution during an undergraduate biology course. For more details about how to teach evolution look up The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species, and observing living organisms. Evolution is not a distant moment; it is an ongoing process. Bacteria mutate and resist antibiotics, 에볼루션 바카라 사이트 바카라 체험 - Continue, viruses evolve and escape new drugs, and animals adapt their behavior in response to the changing climate. The resulting changes are often easy to see.

It wasn't until the 1980s that biologists began to realize that natural selection was at work. The key is the fact that different traits result in the ability to survive at different rates as well as reproduction, and may be passed down from one generation to another.

In the past, when one particular allele - the genetic sequence that defines color in a population of interbreeding organisms, it might quickly become more prevalent than all other alleles. In time, 에볼루션 코리아 this could mean that the number of moths with black pigmentation in a group may increase. The same is true for 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, as with bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from one strain. Samples from each population have been collected regularly, and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's work has demonstrated that a mutation can dramatically alter the speed at the rate at which a population reproduces, and consequently, the rate at which it evolves. It also shows that evolution takes time, a fact that many find difficult to accept.

Another example of microevolution is the way mosquito genes for resistance to pesticides appear more frequently in populations where insecticides are used. That's because the use of pesticides creates a pressure that favors those with resistant genotypes.

The rapidity of evolution has led to a greater appreciation of its importance particularly in a world shaped largely by human activity. This includes climate change, pollution, and habitat loss that prevents many species from adapting. Understanding the evolution process can help us make better decisions about the future of our planet, as well as the life of its inhabitants.