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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 affects all areas of scientific research.

This site provides students, teachers and general readers with a variety 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 is an ancient symbol of the interconnectedness of life. It is seen in a variety of spiritual traditions and cultures as a symbol of unity and love. It also has practical applications, such as providing a framework to understand the history of species and how they respond to changing environmental conditions.

Early attempts to represent the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods, which rely on the sampling of different parts of organisms, or DNA fragments have significantly increased the diversity of a tree of Life2. These trees are mostly populated by eukaryotes and bacteria are largely underrepresented3,4.

Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. In particular, molecular methods allow us to build trees by using sequenced markers like the small subunit of 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 particularly true for microorganisms, which are difficult to cultivate and are typically only found in a single sample5. A recent analysis of all genomes that are known has created a rough draft of the Tree of Life, including a large number of archaea and bacteria that have not been isolated and which are not well understood.

The expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if certain habitats require special protection. The information is useful in a variety of ways, including finding new drugs, fighting diseases and enhancing crops. The information is also valuable to conservation efforts. It helps biologists determine the areas most likely to contain cryptic species with potentially important metabolic functions that could be at risk from anthropogenic change. Although funding to safeguard biodiversity are vital but the most effective way to ensure the preservation of biodiversity around the world is for more people in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between species. Utilizing molecular data, morphological similarities and differences or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree that illustrates the evolutionary relationships between taxonomic groups. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and have evolved from a common ancestor. These shared traits could be analogous, or homologous. Homologous traits are similar in their underlying evolutionary path and 에볼루션 슬롯게임 analogous traits appear like they do, but don't have the same origins. Scientists combine similar traits into a grouping called a clade. All members of a clade have a common trait, such as amniotic egg production. They all evolved from an ancestor that had these eggs. A phylogenetic tree is constructed by connecting the clades to determine the organisms which are the closest to one another.

For a more detailed and 에볼루션 무료 바카라게이밍 (recommended) accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to establish the connections between organisms. This data is more precise than the morphological data and provides evidence of the evolution history of an individual or group. Molecular data allows researchers to determine the number of organisms that share a common ancestor and to estimate their evolutionary age.

Phylogenetic relationships can be affected by a number of factors, including phenotypicplasticity. This is a kind of behavior that alters due to specific environmental conditions. This can cause a trait to appear more similar in one species than another, clouding the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates a combination of homologous and analogous traits in the tree.

Additionally, phylogenetics can help predict the duration and rate at which speciation occurs. This information will assist conservation biologists in making choices about which species to safeguard from extinction. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme in evolution is that organisms change over time as a result of their interactions with their environment. Many theories of evolution have been proposed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that could be passed on to offspring.

In the 1930s and 1940s, concepts from a variety of fields -- including genetics, natural selection, and particulate inheritance -- came together to form the modern synthesis of evolutionary theory which explains how evolution happens through the variations of genes within a population, and how those variants change over time as a result of natural selection. This model, which is known as genetic drift or mutation, gene flow, and sexual selection, is a cornerstone of the current evolutionary biology and can be mathematically explained.

Recent discoveries in evolutionary developmental biology have shown how variation 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 others such as directional selection or genetic erosion (changes in the frequency of the genotype over time) can lead to evolution which is defined by changes in the genome of the species over time, and also by changes in phenotype over time (the expression of that genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence for evolution increased students' acceptance of evolution in a college biology course. For more information on how to teach about evolution, see 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 traditionally studied evolution by looking in the past, analyzing fossils and comparing species. They also study living organisms. But evolution isn't just something that occurred in the past; it's an ongoing process, taking place right now. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of a changing environment. The resulting changes are often evident.

It wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The reason is that different characteristics result in different rates of survival and reproduction (differential fitness) and can be passed down from one generation to the next.

In the past, if an allele - the genetic sequence that determines colour appeared in a population of organisms that interbred, it could become more common than other allele. Over time, that would mean the number of black moths in a population could increase. The same is true for many other characteristics--including morphology and 에볼루션 카지노 behavior--that vary among populations of organisms.

The ability to observe evolutionary change is easier when a species has a fast generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from one strain. The samples of each population have been taken frequently and more than 50,000 generations of E.coli have passed.

Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the effectiveness at which a population reproduces. It also shows that evolution takes time, a fact that some are unable to accept.

Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more common in populations where insecticides are used. This is due to pesticides causing a selective pressure which favors individuals who have resistant genotypes.

The speed at which evolution can take place has led to a growing recognition of its importance in a world shaped by human activity, including climate change, pollution and the loss of habitats that hinder many species from adapting. Understanding the evolution process can help us make better choices about the future of our planet, and the life of its inhabitants.