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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 concept of evolution and how it influences every area of scientific inquiry.

This site provides a range of sources for students, teachers as well as general readers about evolution. It contains key video clips from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that represents the interconnectedness of all life. It appears in many religions and cultures as a symbol of unity and love. It also has practical applications, such as providing a framework for understanding the history of species and how they respond to changing environmental conditions.

Early attempts to describe the biological world were founded on categorizing organisms on their physical and 에볼루션게이밍 metabolic characteristics. These methods, which rely on the sampling of different parts of living organisms or 에볼루션코리아 sequences of 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 not represented in a large way3,4.

In avoiding the necessity of direct experimentation and observation genetic techniques have allowed us to represent the Tree of Life in a much more accurate way. We can construct trees using molecular techniques such as the small subunit ribosomal gene.

The Tree of Life has been dramatically expanded through genome sequencing. However there is a lot of diversity to be discovered. This is particularly true for microorganisms, which can be difficult to cultivate and are often only present in a single specimen5. Recent analysis of all genomes resulted in an unfinished draft of the Tree of Life. This includes a wide range of archaea, 에볼루션 코리아 바카라 사이트 - Funsilo.Date - bacteria and other organisms that have not yet been identified or their diversity is not thoroughly understood6.

This expanded Tree of Life can be used to evaluate the biodiversity of a particular area and 에볼루션카지노 determine if specific habitats require special protection. This information can be utilized in a variety of ways, including identifying new drugs, combating diseases and improving the quality of crops. This information is also extremely useful in conservation efforts. It can help biologists identify those areas that are most likely contain cryptic species with important metabolic functions that could be at risk of anthropogenic changes. While funds to protect biodiversity are essential, ultimately the best way to protect the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, reveals the relationships between various groups of organisms. Utilizing molecular data similarities and differences in morphology or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree that illustrates the evolution of taxonomic categories. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that evolved from common ancestors. These shared traits could be analogous or homologous. Homologous traits are the same in their evolutionary journey. Analogous traits might appear like they are, but they do not have the same ancestry. Scientists organize similar traits into a grouping called a clade. All members of a clade share a characteristic, like amniotic egg production. They all evolved from an ancestor who had these eggs. The clades are then linked to form a phylogenetic branch to determine which organisms have the closest connection to each other.

Scientists make use of DNA or RNA molecular information to build a phylogenetic chart that is more accurate and precise. This data is more precise than morphological information and provides evidence of the evolutionary history of an organism or group. The analysis of molecular data can help researchers identify the number of species that have the same ancestor and estimate their evolutionary age.

The phylogenetic relationships between organisms can be affected by a variety of factors including phenotypic plasticity, a kind of behavior that changes in response to unique environmental conditions. This can cause a particular 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 homologous and analogous features in the tree.

Additionally, phylogenetics aids determine the duration and speed at which speciation takes place. This information can assist conservation biologists in making decisions about which species to safeguard from disappearance. In the end, it is the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms develop different features over time based on their interactions with their surroundings. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would develop according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can cause changes that can be passed on to future generations.

In the 1930s and 1940s, ideas from different areas, including genetics, natural selection and particulate inheritance, merged to create a modern synthesis of evolution theory. This describes how evolution happens through the variation in genes within the population, and how these variants change over time as a result of natural selection. This model, known as genetic drift or mutation, gene flow, and sexual selection, is the foundation of modern evolutionary biology and can be mathematically explained.

Recent advances in evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species through mutations, genetic drift, reshuffling genes during sexual reproduction and the movement between populations. These processes, along with others, such as directionally-selected selection and erosion of genes (changes in the frequency of genotypes over time) can result in 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 the concept of phylogeny through incorporating evolutionary thinking throughout all areas of biology. In a recent study by Grunspan et al. It was found that teaching students about the evidence for evolution increased their acceptance of evolution during a college-level course in biology. For more information on how to teach about evolution, please read The Evolutionary Potential of All Areas of Biology and 에볼루션 사이트 Thinking Evolutionarily: 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 event; it is an ongoing process that continues to be observed today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior because of the changing environment. The results are often visible.

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

In the past, if one allele - the genetic sequence that determines colour appeared in a population of organisms that interbred, it could be more common than any other allele. Over time, that would mean that the number of black moths in a population 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 much easier when a species has a fast generation turnover, as with bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. Samples from each population have been taken frequently and more than 50,000 generations of E.coli have passed.

Lenski's research has revealed that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows that evolution takes time, something that is difficult for some to accept.

Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides are used. This is due to pesticides causing an exclusive pressure that favors those with resistant genotypes.

The speed at which evolution takes place has led to an increasing awareness of its significance in a world that is shaped by human activity--including climate change, pollution, and the loss of habitats which prevent the species from adapting. Understanding evolution will assist you in making better choices regarding the future of the planet and its inhabitants.