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The Academy's Evolution Site

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

This site provides students, teachers and general readers with a range of educational resources on evolution. It has important video clips from NOVA and WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of all life. It is an emblem of love and unity across many cultures. It has many practical applications in addition to providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.

The first attempts to depict the biological world were built on categorizing organisms based on their physical and 에볼루션사이트 metabolic characteristics. These methods rely on the sampling of different parts of organisms or short fragments of DNA, have greatly increased the diversity of a Tree of Life2. However these trees are mainly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

By avoiding the necessity for direct observation and experimentation, genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. In particular, molecular methods enable us to create trees using sequenced markers, such as the small subunit ribosomal RNA gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially the case for microorganisms which are difficult to cultivate, and are typically found in a single specimen5. A recent study of all genomes that are known has produced a rough draft of the Tree of Life, including a large number of bacteria and archaea that have not been isolated and whose diversity is poorly understood6.

This expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine if specific habitats require protection. The information can be used in a range of ways, from identifying new treatments to fight disease to enhancing the quality of crops. This information is also extremely beneficial in conservation efforts. It helps biologists discover areas most likely to be home to cryptic species, which could have vital metabolic functions and are susceptible to human-induced change. While conservation funds are important, the best way to conserve the world's biodiversity is to empower more people in developing nations with the necessary knowledge to act locally and support conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between organisms. Utilizing molecular data as well as morphological similarities and distinctions or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree that illustrates the evolution of taxonomic groups. The role of phylogeny is crucial in understanding biodiversity, genetics and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from an ancestor that shared traits. These shared traits are either homologous or analogous. Homologous traits are similar in their evolutionary origins, while analogous traits look like they do, but don't have the identical origins. Scientists put similar traits into a grouping called a the clade. For example, all of the organisms in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor which had eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms that are most closely related to each other.

For a more detailed and accurate phylogenetic tree scientists use molecular data from DNA or RNA to determine the relationships between organisms. This information is more precise and provides evidence of the evolution history of an organism. The use of molecular data lets researchers determine the number of organisms that share the same ancestor and estimate their evolutionary age.

The phylogenetic relationship can be affected by a variety of factors, including phenotypicplasticity. This is a type of behavior that alters as a result of specific environmental conditions. This can cause a characteristic to appear more similar to one species than to another and 에볼루션 바카라 obscure the phylogenetic signals. However, this problem can be solved through the use of techniques such as cladistics which combine analogous and homologous features into the tree.

Furthermore, phylogenetics may help predict the length and speed of speciation. This information can aid conservation biologists in making choices about which species to protect from disappearance. In the end, it's the conservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their environments. Many theories of evolution have been developed by a wide variety 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, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits cause changes that could be passed on to the offspring.

In the 1930s and 1940s, theories from various fields, including genetics, natural selection and 에볼루션 사이트 particulate inheritance, merged to form a modern synthesis of evolution theory. This defines how evolution occurs by the variations in genes within a population and how these variants change with time due to natural selection. This model, which encompasses genetic drift, mutations, gene flow and sexual selection can be mathematically described mathematically.

Recent advances in the field of evolutionary developmental biology have shown the ways in which variation can be introduced to a species through genetic drift, mutations, reshuffling 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 a genotype over time) can lead to evolution which is defined by change in the genome of the species over time and also by changes in phenotype over time (the expression of the genotype within the individual).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking throughout all areas of biology. In a recent study by Grunspan et al., it was shown that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. For more information on how to teach about evolution, read The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have 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 that is that is taking place right now. Bacteria transform and resist antibiotics, viruses re-invent themselves and elude new medications and animals alter their behavior 에볼루션 카지노 in response to the changing climate. The results are usually evident.

It wasn't until late 1980s that biologists understood that natural selection can be observed in action as well. The key to this is that different traits confer a different rate of survival and reproduction, and they can be passed on from one generation to another.

In the past, if a certain allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could be more common than any other allele. As time passes, that could mean that the number of black moths in a particular population could rise. The same is true for 에볼루션사이트 many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to see evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from one strain. Samples of each population have been collected frequently and more than 50,000 generations of E.coli have passed.

Lenski's work has demonstrated that mutations can drastically alter the efficiency with which a population reproduces and, consequently the rate at which it changes. It also proves that evolution is slow-moving, a fact that some people find difficult to accept.

Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in areas that have used insecticides. That's because the use of pesticides causes a selective pressure that favors individuals with resistant genotypes.

The rapid pace at which evolution takes place has led to an increasing awareness of its significance in a world that is shaped by human activities, including climate changes, pollution and the loss of habitats that hinder many species from adjusting. Understanding evolution can aid you in making better decisions regarding the future of the planet and its inhabitants.