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The Academy's Evolution Site

Biological evolution is one of the most central concepts in biology. The Academies are involved in helping those interested in science learn about the theory of evolution and how it can be applied throughout all fields 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 that represents the interconnectedness of all life. It appears in many spiritual traditions and cultures as an emblem of unity and love. It has numerous practical applications in addition to providing a framework to understand the history of species and how they respond to changing environmental conditions.

Early approaches to depicting the world of biology focused on categorizing organisms into distinct categories that were identified by their physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms or on sequences of small DNA fragments, significantly increased the variety that could be included in the tree of life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity is not represented in a large way3,4.

By avoiding the need for direct experimentation and 에볼루션 바카라 체험 observation, genetic techniques have allowed us to depict the Tree of Life in a more precise manner. We can construct trees using molecular methods like the small-subunit ribosomal gene.

The Tree of Life has been dramatically expanded through genome sequencing. However there is still a lot of biodiversity to be discovered. This is especially the case for microorganisms which are difficult to cultivate and are typically present in a single sample5. A recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that have not yet been identified or their diversity is not fully understood6.

The expanded Tree of Life can be used to determine the diversity of a particular area and determine if certain habitats require special protection. This information can be used in a range of ways, from identifying the most effective remedies to fight diseases to improving the quality of crops. It is also valuable for conservation efforts. It can aid biologists in identifying areas that are likely to have species that are cryptic, which could have vital metabolic functions and be vulnerable to the effects of human activity. While funds to protect biodiversity are essential however, the most effective method to protect the world's biodiversity is for more people living in developing countries to be empowered with the necessary knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) depicts the relationships between species. Scientists can construct a phylogenetic chart that shows the evolutionary relationships between taxonomic groups based on molecular data 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 Identifies the relationships between organisms that have similar characteristics and have evolved from an ancestor with common traits. These shared traits may be homologous, or analogous. Homologous traits share their evolutionary roots, while analogous traits look similar, but do not share the identical origins. Scientists arrange similar traits into a grouping known as a clade. Every organism in a group have a common trait, such as amniotic egg production. They all derived from an ancestor who had these eggs. A phylogenetic tree is then constructed by connecting the clades to identify the species which are the closest to one another.

Scientists use DNA or RNA molecular data to create a phylogenetic chart which is more precise and detailed. This data is more precise than the morphological data and provides evidence of the evolution background of an organism or group. Researchers can use Molecular Data to determine the age of evolution of organisms and determine how many species have the same ancestor.

Phylogenetic relationships can be affected by a number of factors, including the phenomenon of phenotypicplasticity. This is a type behavior that changes as a result of unique environmental conditions. This can cause a trait to appear more similar to a species than another and obscure the phylogenetic signals. However, this problem can be cured by the use of techniques such as cladistics which combine analogous and homologous features into the tree.

Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information can aid conservation biologists in deciding which species to safeguard from extinction. It is ultimately the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire different features over time due to their interactions with their surroundings. Many theories of evolution have been proposed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that could be passed onto offspring.

In the 1930s and 1940s, concepts from various fields, such as natural selection, genetics & particulate inheritance, came together to form a modern evolutionary theory. This describes how evolution is triggered by the variation of genes in the population, and how these variations change with time due to natural selection. This model, which encompasses genetic drift, mutations as well as gene flow and sexual selection can be mathematically described mathematically.

Recent discoveries in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species by genetic drift, mutation, and reshuffling of genes in sexual reproduction, and also through migration 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 the change in phenotype as time passes (the expression of that genotype in the individual).

Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking into all areas of biology. In a study by Grunspan and co., it was shown that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. To find out more about how to teach about evolution, look up The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for 에볼루션 바카라 체험 코리아 [saleh-gallegos-2.Blogbright.Net] Infusing the Concept of Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution through looking back--analyzing fossils, comparing species, and 에볼루션 바카라 무료체험 studying living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process that is taking place in the present. Bacteria transform and resist antibiotics, viruses evolve and are able to evade new medications, and 에볼루션카지노 animals adapt their behavior in response to the changing environment. The changes that result are often apparent.

It wasn't until the late 1980s when biologists began to realize that natural selection was also in action. The key is that different traits have different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.

In the past, 에볼루션 코리아 when one particular allele--the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it could rapidly become more common than the other alleles. In time, this could mean the number of black moths in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

The ability to observe evolutionary change is easier when a particular species has a rapid turnover of its generation such as bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples from each population are taken regularly and more than 500.000 generations have passed.

Lenski's work has demonstrated that mutations can drastically 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 is hard for some to accept.

Another example of microevolution is that mosquito genes that are resistant to pesticides appear more frequently in populations in which insecticides are utilized. That's because the use of pesticides creates a pressure that favors people with resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance, 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 the evolution process can help us make better decisions regarding the future of our planet and the life of its inhabitants.