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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 people who are interested in science comprehend the concept of evolution and how it permeates all areas of scientific research.

This site provides teachers, students and general readers with a wide range of learning resources 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 of the interconnectedness of life. It is a symbol of love and unity across many cultures. It has many practical applications in addition to providing a framework to understand the history of species and how they react to changing environmental conditions.

The first attempts at depicting the world of biology focused on the classification of organisms into distinct categories that were identified by their physical and metabolic characteristics1. These methods are based on the collection of various parts of organisms, or 무료 에볼루션 바카라 무료 (use Sciencewiki) fragments of DNA, have greatly increased the diversity of a Tree of Life2. These trees are largely composed of eukaryotes, while bacteria are largely underrepresented3,4.

By avoiding the necessity for direct experimentation and observation, genetic techniques have allowed us to depict the Tree of Life in a more precise manner. Particularly, 에볼루션 바카라 무료체험 molecular techniques enable us to create trees using sequenced markers like the small subunit ribosomal gene.

The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much diversity to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are typically only found in a single sample5. Recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a wide range of bacteria, archaea and other organisms that haven't yet been isolated or whose diversity has not been thoroughly understood6.

This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if particular habitats need special protection. This information can be utilized in many ways, including finding new drugs, battling diseases and enhancing crops. It is also beneficial in conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species that could have important metabolic functions that could be at risk from anthropogenic change. Although funds to protect biodiversity are essential however, the most effective method 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 in order to promote conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between organisms. Scientists can construct an phylogenetic chart which shows the evolution of taxonomic groups based on molecular data and morphological similarities or differences. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that evolved from common ancestral. These shared traits can be homologous, or analogous. Homologous characteristics are identical in terms of their evolutionary journey. Analogous traits could appear similar however they do not have the same ancestry. Scientists group similar traits together into a grouping known as a the clade. All organisms in a group have a common characteristic, like amniotic egg production. They all came from an ancestor who had these eggs. The clades are then linked to form a phylogenetic branch that can determine which organisms have the closest connection to each other.

Scientists make use of DNA or RNA molecular information to create a phylogenetic chart that is more accurate and detailed. This information is more precise and gives evidence of the evolution history of an organism. The use of molecular data lets researchers identify the number of species that share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships between species are influenced by many factors, including phenotypic plasticity a kind of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more resembling to one species than another, obscuring the phylogenetic signals. This problem can be mitigated by using cladistics. This is a method that incorporates the combination of analogous and 에볼루션 코리아 homologous features in the tree.

Furthermore, phylogenetics may aid in predicting the duration and rate of speciation. This information can help conservation biologists decide which species to protect from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which will result in a complete and balanced ecosystem.

Evolutionary Theory

The main idea behind evolution is that organisms change over time as a result of their interactions with their environment. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would evolve according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy and 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, theories from various areas, including genetics, natural selection, and particulate inheritance, were brought together to create a modern synthesis of evolution theory. This describes how evolution is triggered by the variation in genes within a population and how these variations change over time as a result of natural selection. This model, called genetic drift mutation, gene flow and sexual selection, is the foundation of current evolutionary biology, and can be mathematically explained.

Recent developments in evolutionary developmental biology have revealed the ways in which variation can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, as well as others 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 over time (the expression of the genotype in an individual).

Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny and evolutionary. A recent study conducted by Grunspan and colleagues, 무료 에볼루션 for example demonstrated that teaching about the evidence for evolution helped students accept the concept of evolution in a college biology class. To learn more about how to teach about evolution, please see 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 through looking back--analyzing 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 taking place right now. Bacteria mutate and 에볼루션 바카라 체험 resist antibiotics, viruses evolve and elude new medications, and animals adapt their behavior in response to the changing environment. The changes that occur are often 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 the ability to survive at different rates and reproduction, and can be passed down from one generation to the next.

In the past, if one allele - the genetic sequence that determines color - was found in a group of organisms that interbred, it might become more common than any other allele. As time passes, that could mean the number of black moths within a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to observe evolution when a species, such as bacteria, has a high generation turnover. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each population are taken on a regular basis, and over 50,000 generations have now been observed.

Lenski's research has revealed that mutations can drastically alter the speed at which a population reproduces--and so, the rate at which it alters. It also shows evolution takes time, something that is hard for some to accept.

Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more common in populations where insecticides are used. This is due to pesticides causing an enticement that favors those who have resistant genotypes.

The rapidity of evolution has led to a greater recognition of its importance particularly in a world that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding evolution can help you make better decisions regarding the future of the planet and its inhabitants.