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The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies are committed to helping those interested in the sciences learn about the theory of evolution and how it is permeated in all areas of scientific research.

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

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is an emblem of love and unity in many cultures. It has numerous practical applications as well, including providing a framework for understanding the history of species, and how they react to changing environmental conditions.

Early attempts to describe the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, which depend on the collection of various parts of organisms or DNA fragments, have significantly increased the diversity of a tree of Life2. The trees are mostly composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.

Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Trees can be constructed by using molecular methods like the small-subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is a lot of diversity to be discovered. This is especially relevant to microorganisms that are difficult to cultivate and are typically found in a single specimen5. A recent study of all genomes known to date has created a rough draft of the Tree of Life, including numerous bacteria and archaea that are not isolated and 에볼루션카지노사이트 their diversity is not fully understood6.

This expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine whether specific habitats require special protection. This information can be utilized in a variety of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of crop yields. The information is also incredibly beneficial for conservation efforts. It helps biologists discover areas that are likely to have species that are cryptic, which could have important metabolic functions and are susceptible to changes caused by humans. While funds to protect biodiversity are essential, the best method to protect the world's biodiversity is to empower the people of developing nations with the necessary knowledge to act locally and support conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) depicts the relationships between different organisms. By using molecular information as well as morphological similarities and distinctions or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree which illustrates the evolutionary relationship between taxonomic groups. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms that have similar characteristics and have evolved from an ancestor that shared traits. These shared traits can be analogous or homologous. Homologous traits share their evolutionary origins while analogous traits appear similar but do not have the same origins. Scientists group similar traits together into a grouping known as a Clade. For example, all of the organisms that make up a clade have the characteristic of having amniotic eggs and evolved from a common ancestor which had these eggs. A phylogenetic tree can be constructed by connecting the clades to determine the organisms which are the closest to each other.

For a more precise and precise phylogenetic tree scientists use molecular data from DNA or RNA to identify the connections between organisms. This information is more precise and gives evidence of the evolutionary history of an organism. The use of molecular data lets researchers identify the number of species who share the same ancestor and estimate their evolutionary age.

The phylogenetic relationship can be affected by a variety of factors that include the phenotypic plasticity. This is a type of behavior that alters due to unique environmental conditions. This can cause a particular trait to appear more similar in one species than another, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which incorporates an amalgamation of analogous and homologous features in the tree.

Additionally, 에볼루션 바카라 무료 phylogenetics aids determine the duration and speed at which speciation occurs. This information can aid conservation biologists in making choices about which species to save from disappearance. In the end, it's the conservation of phylogenetic variety that will result in an ecosystem that is balanced and complete.

Evolutionary Theory

The fundamental concept of evolution is that organisms develop various characteristics over time as a result of their interactions with their environments. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could evolve according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of certain traits can result in changes that are passed on to the next generation.

In the 1930s and 1940s, concepts from a variety of fields -- including genetics, natural selection and particulate inheritance - came together to create the modern evolutionary theory synthesis which explains how evolution occurs through the variation of genes within a population, and how those variations change over time due to natural selection. This model, 에볼루션 바카라 무료 룰렛 (http://www.hondacityclub.com/all_new/home.php?mod=space&uid=2103977) called genetic drift or mutation, gene flow, and sexual selection, is a key element of modern evolutionary biology and can be mathematically explained.

Recent advances in the field of evolutionary developmental biology have shown how variation can be introduced to a species via genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time) can result in evolution, which is defined by change in the genome of the species over time and also the change 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 aspects of biology. A recent study conducted by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution helped students accept the concept of evolution in a college biology class. For more information on how to teach about evolution, please read The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution by studying fossils, comparing species and observing living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process that is happening right now. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of a changing environment. The changes that occur are often apparent.

But it wasn't until the late-1980s that biologists realized that natural selection could be observed in action as well. The reason 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 particular allele, the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it could quickly become more common than all other alleles. In time, this could mean the number of black moths in a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to track evolution when the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. Samples from each population were taken frequently and more than 500.000 generations of E.coli have passed.

Lenski's research has shown that a mutation can profoundly alter the efficiency with which a population reproduces--and so, the rate at which it changes. It also demonstrates that evolution takes time--a fact that some people are unable to accept.

Another example of microevolution is the way mosquito genes for 에볼루션 바카라 무료 resistance to pesticides appear more frequently in areas in which insecticides are utilized. That's because the use of pesticides creates a pressure that favors individuals with resistant genotypes.

The rapid pace 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 which prevent many species from adapting. Understanding the evolution process will aid you in making better decisions regarding the future of the planet and its inhabitants.