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The Academy's Evolution Site

Biological evolution is one of the most important concepts in biology. The Academies are involved in helping those interested in science comprehend the evolution theory and how it is incorporated throughout all fields of scientific research.

This site provides students, teachers and general readers with a range of learning resources about evolution. It also includes 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 life. It is a symbol of love and 에볼루션 코리아 harmony in a variety of cultures. It has numerous practical applications as well, such as providing a framework to understand the history of species and how they respond to changing environmental conditions.

The first attempts at depicting the biological world focused on the classification of organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms or sequences of small fragments of their DNA significantly expanded the diversity that could be included in the tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

By avoiding the need for direct experimentation and observation genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. Particularly, molecular methods allow us to construct trees by using sequenced markers, such as the small subunit ribosomal RNA gene.

Despite the massive expansion of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is particularly the case for microorganisms which are difficult to cultivate, and are usually present in a single sample5. A recent study of all genomes known to date has created 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, assisting to determine if specific habitats require special protection. The information can be used in a range of ways, from identifying new remedies to fight diseases to enhancing the quality of crops. This information is also extremely beneficial to conservation efforts. It can help biologists identify the areas most likely to contain cryptic species with potentially important metabolic functions that could be at risk of anthropogenic changes. While funds to protect biodiversity are essential but the most effective 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 known as an evolutionary tree) shows the relationships between different organisms. Scientists can create a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological similarities or differences. The concept of phylogeny is fundamental to understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and 무료 에볼루션 evolved from an ancestor that shared traits. These shared traits can be either homologous or analogous. Homologous characteristics are identical in their evolutionary journey. Analogous traits might appear similar however they do not have the same origins. Scientists organize similar traits into a grouping referred to as a Clade. For example, all of the species in a clade share the characteristic of having amniotic eggs. They evolved from a common ancestor that had these eggs. A phylogenetic tree is built by connecting the clades to identify the organisms that are most closely related to each other.

Scientists utilize molecular DNA or RNA data to construct a phylogenetic graph that is more accurate and precise. This data is more precise than the morphological data and provides evidence of the evolutionary history of an individual or group. The analysis of molecular data can help researchers identify the number of species who share a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships between species are influenced by many factors, including phenotypic plasticity an aspect of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more similar to a species than another and obscure the phylogenetic signals. However, this issue can be cured by the use of methods such as cladistics which combine analogous and homologous features into the tree.

In addition, 에볼루션 phylogenetics can help predict the time and pace of speciation. This information can help conservation biologists make decisions about which species to protect from extinction. In the end, it is the conservation of phylogenetic variety that will result in an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme of evolution is that organisms develop different features over time as a result of their interactions with their surroundings. A variety of theories about evolution have been developed by a wide variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to 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 use or disuse of traits causes changes that can be passed on to offspring.

In the 1930s and 1940s, ideas from a variety of fields--including natural selection, genetics, and particulate inheritance - came together to create 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 incorporates genetic drift, mutations as well as gene flow and sexual selection can be mathematically described mathematically.

Recent developments in the field of evolutionary developmental biology have revealed that variations can be introduced into a species through mutation, genetic drift, and reshuffling of genes during sexual reproduction, as well as by migration between populations. These processes, 에볼루션 바카라 무료체험 along with other ones 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 changes in the genome of the species over time, and also by changes in phenotype as time passes (the expression of the genotype within the individual).

Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny as well as evolution. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence supporting evolution helped students accept the concept of evolution in a college-level biology class. To learn more about how to teach about evolution, please look up The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also study living organisms. Evolution is not a past moment; it is a process that continues today. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior as a result of the changing environment. The results are often apparent.

It wasn't until the 1980s that biologists began realize that natural selection was at work. The key is that different traits confer different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.

In the past, if one particular allele--the genetic sequence that controls coloration - was present in a group of interbreeding species, it could quickly become more prevalent than all other alleles. As time passes, that could mean the number of black moths within a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Observing evolutionary change in action is much easier when a species has a rapid turnover of its generation like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from one strain. Samples of each population have been taken regularly and more than 50,000 generations of E.coli have passed.

Lenski's research has revealed that a mutation can profoundly alter the efficiency with which a population reproduces and, consequently the rate at which it alters. It also shows that evolution takes time, something that is difficult for 바카라 에볼루션 some to accept.

Microevolution is also evident 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 a selective pressure which favors individuals who have resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance especially in a planet that is largely shaped by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding evolution can help us make smarter choices about the future of our planet, as well as the lives of its inhabitants.