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The Academy's Evolution Site

Biological evolution is one of the most fundamental concepts in biology. The Academies are committed to helping those who are interested in science to 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 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, an ancient symbol, represents the interconnectedness of all life. It is seen in a variety of religions and cultures as a symbol of unity and love. It also has practical uses, like providing a framework to understand the evolution of species and how they respond to changes in the environment.

Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on the sampling of various parts of living organisms or on small fragments of their DNA, greatly increased the variety of organisms that could be included in a tree of life2. These trees are largely composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. We can construct trees using molecular techniques such as the small subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However, there is still much biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are typically found in one sample5. A recent study of all genomes that are known has produced a rough draft version of the Tree of Life, including a large number of archaea and bacteria that have not been isolated, and which are not well understood.

This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if specific habitats need special protection. This information can be used in a variety of ways, including identifying new drugs, combating diseases and enhancing crops. This information is also extremely valuable for conservation efforts. It can help biologists identify areas that are likely to be home to cryptic species, which could perform important metabolic functions and are susceptible to the effects of human activity. While conservation funds are important, the best way to conserve the world's biodiversity is to equip more people in developing countries with the information they require to take action locally and encourage conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) shows the relationships between organisms. By using molecular information similarities and differences in morphology, or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree which illustrates the evolutionary relationships between taxonomic groups. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and 에볼루션 룰렛 evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestors. These shared traits could be analogous or homologous. Homologous traits are identical in their evolutionary origins, while analogous traits look like they do, but don't have the same origins. Scientists put similar traits into a grouping known as a clade. For example, all of the organisms in a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor who had these eggs. The clades then join to form a phylogenetic branch that can determine which organisms have the closest connection to each other.

Scientists make use of molecular DNA or RNA data to build a phylogenetic chart which is more precise and detailed. This data is more precise than morphological information and provides evidence of the evolutionary history of an organism or group. The use of molecular data lets researchers determine the number of species who share the same ancestor and estimate their evolutionary age.

The phylogenetic relationships of a species can be affected by a number of factors that include phenotypicplasticity. This is a type of behavior that changes in response to particular environmental conditions. This can cause a particular trait to appear more similar in one species than other species, which can obscure the phylogenetic signal. However, this problem can be cured by the use of methods such as cladistics which incorporate a combination of analogous and homologous features into the tree.

In addition, phylogenetics can aid in predicting the time and pace of speciation. This information can assist conservation biologists in making choices about which species to protect from disappearance. It is ultimately the preservation of phylogenetic diversity that will create an ecologically balanced and complete ecosystem.

Evolutionary Theory

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

In the 1930s and 1940s, ideas from various fields, including natural selection, genetics, and particulate inheritance--came together to form the modern evolutionary theory synthesis, which defines how evolution happens through the variation of genes within a population and 에볼루션 바카라코리아 (Telegra.Ph) how these variants change over time due to natural selection. This model, which incorporates genetic drift, mutations in gene flow, and 에볼루션 게이밍 sexual selection can be mathematically described mathematically.

Recent developments in evolutionary developmental biology have demonstrated how variations can be introduced to a species through genetic drift, 에볼루션 바카라 무료체험 mutations and reshuffling of genes during sexual reproduction, and even migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of the 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 in an individual).

Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny and evolution. In a study by Grunspan and co., 에볼루션 it was shown that teaching students about the evidence for evolution boosted their understanding of evolution during the course of a college biology. For more information on how to teach about evolution look up The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily A Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution through studying fossils, comparing species and studying living organisms. Evolution is not a distant event, but an ongoing process that continues to be observed today. Bacteria mutate and resist antibiotics, viruses reinvent themselves and escape new drugs, and animals adapt their behavior to the changing environment. The resulting changes are often easy to see.

It wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The key is that various traits have different rates of survival and reproduction (differential fitness) and 에볼루션 룰렛 are passed from one generation to the next.

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

It is easier to see evolutionary change when a species, such as bacteria, has a rapid generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each are taken regularly and over 50,000 generations have now passed.

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

Another example of microevolution is how mosquito genes for resistance to pesticides are more prevalent in areas in which insecticides are utilized. That's because the use of pesticides creates a pressure that favors individuals who have resistant genotypes.

The rapidity of evolution has led to a growing appreciation of its importance, especially in a world that is largely shaped by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution will help us make better decisions about the future of our planet, and the lives of its inhabitants.