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The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies have long been involved in helping those interested in science understand the theory of evolution and how it affects all areas of scientific exploration.

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

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It appears in many cultures and spiritual beliefs as symbolizing unity and love. It also has practical uses, like providing a framework to understand the evolution of species and how they react to changes in environmental conditions.

The first attempts to depict the world of biology were founded on categorizing organisms on their metabolic and physical characteristics. These methods, which rely on the sampling of different parts of organisms, 에볼루션코리아 or DNA fragments have greatly increased the diversity of a Tree of Life2. The trees are mostly composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to construct trees using sequenced markers, such as the small subunit ribosomal RNA gene.

Despite the dramatic expansion of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are usually found in a single specimen5. Recent analysis of all genomes has produced an unfinished draft of a Tree of Life. This includes a large number of bacteria, archaea and other organisms that haven't yet been identified or whose diversity has not been well understood6.

The expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if particular habitats need special protection. This information can be used in a variety of ways, from identifying new medicines to combating disease to improving the quality of crops. This information is also valuable to conservation efforts. It can help biologists identify the areas most likely to contain cryptic species that could have important metabolic functions that may be at risk of anthropogenic changes. Although funding to protect biodiversity are crucial, ultimately the best way to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny (also known as an evolutionary tree) shows the relationships between different organisms. Using molecular data, morphological similarities and differences or ontogeny (the process of the development of an organism) scientists can create an phylogenetic tree that demonstrates the evolution of taxonomic groups. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from a common ancestor. These shared traits could be either analogous or homologous. Homologous traits are similar in terms of their evolutionary journey. Analogous traits might appear like they are but they don't share the same origins. Scientists combine similar traits into a grouping known as a Clade. All organisms in a group have a common characteristic, for example, 에볼루션 룰렛; Telegra.Ph, amniotic egg production. They all came from an ancestor with these eggs. A phylogenetic tree is built by connecting the clades to identify the species which are the closest to one another.

Scientists use DNA or RNA molecular data to create a phylogenetic chart that is more precise and detailed. This information is more precise and provides evidence of the evolutionary history of an organism. 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 such as the phenotypic plasticity. This is a type of behavior 에볼루션 코리아 that changes due to specific environmental conditions. This can cause a trait to appear more similar to a species than to another and obscure the phylogenetic signals. However, this problem can be cured by the use of techniques such as cladistics which combine similar and homologous traits into the tree.

Additionally, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists make decisions about the species they should safeguard from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will result in an ecologically balanced and complete ecosystem.

Evolutionary Theory

The central theme of evolution is that organisms acquire distinct characteristics over time based on their interactions with their environment. Several theories of evolutionary change have been proposed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that could be passed on to offspring.

In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection and particulate inheritance - came together to form the modern synthesis of evolutionary theory, which defines 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 incorporates mutations, genetic drift in gene flow, and sexual selection can be mathematically described.

Recent discoveries in evolutionary developmental biology have demonstrated how variation can be introduced to a species by mutations, genetic drift, 에볼루션 reshuffling genes during sexual reproduction and migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can lead to evolution which is defined by change in the genome of the species over time, and also the change in phenotype as time passes (the expression of the genotype within the individual).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all areas of biology. A recent study conducted by Grunspan and colleagues, for example demonstrated that teaching about the evidence for evolution helped students accept the concept of evolution in a college-level biology class. For more information about how to teach evolution read The Evolutionary Power of Biology 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 studying living organisms. But evolution isn't just something that happened in the past. It's an ongoing process, happening today. Viruses reinvent themselves to avoid new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior in the wake of a changing environment. The changes that result are often visible.

It wasn't until late 1980s that biologists understood that natural selection could be observed in action as well. The key is that various traits confer different rates of survival and reproduction (differential fitness) and are passed from one generation to the next.

In the past, if a certain allele - the genetic sequence that determines colour was present in a population of organisms that interbred, it could be more common than other allele. As time passes, that could mean that the number of black moths within a 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 see evolutionary change when the species, 에볼루션 코리아 like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, 에볼루션 바카라 무료 has been tracking twelve populations of E.coli that are descended 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 research has shown that a mutation can dramatically alter the speed at which a population reproduces--and so, the rate at which it evolves. It also shows that evolution takes time--a fact that some find difficult to accept.

Another example of microevolution is how mosquito genes for resistance to pesticides are more prevalent in populations in which insecticides are utilized. Pesticides create an exclusive pressure that favors those with resistant genotypes.

The rapidity of evolution has led to a growing awareness of its significance especially in a planet shaped largely by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution will aid you in making better decisions about the future of the planet and its inhabitants.