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The Academy's Evolution Site

The concept of biological evolution is among the most important concepts in biology. The Academies are involved in helping those interested in science to comprehend the evolution theory and how it can be applied in all areas of scientific research.

This site provides students, teachers and general readers with a range of educational resources on evolution. It includes key video clip 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 a symbol of love and harmony in a variety of cultures. It also has practical applications, like providing a framework to understand the history of species and how they react to changes in environmental conditions.

The first attempts to depict the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely on the sampling of various parts of living organisms or on short fragments of their DNA greatly increased the variety of organisms that could be represented in the tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

In avoiding the necessity of direct observation and experimentation genetic techniques have enabled us to represent the Tree of Life in a more precise way. Particularly, molecular techniques allow us to construct trees using sequenced markers, such as the small subunit ribosomal RNA gene.

The Tree of Life has been significantly expanded by genome sequencing. However, there is still much diversity to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and are typically found in a single specimen5. A recent analysis of all known genomes has produced a rough draft of the Tree of Life, including numerous archaea and bacteria that have not been isolated and which are not well understood.

The expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine whether specific habitats require special protection. This information can be utilized in a variety of ways, including identifying new drugs, combating diseases and enhancing crops. The information is also beneficial for conservation efforts. It helps biologists discover areas that are most likely to have species that are cryptic, which could have vital metabolic functions and are susceptible to changes caused by humans. While funds to protect biodiversity are crucial 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 known as an evolutionary tree) depicts the relationships between species. 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. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar characteristics and have evolved from an ancestor with common traits. These shared traits can be either homologous or analogous. Homologous characteristics are identical in their evolutionary path. Analogous traits may look similar however they do not have the same origins. Scientists group similar traits into a grouping known as a Clade. Every organism in a group have a common characteristic, for example, amniotic egg production. They all derived from an ancestor who had these eggs. The clades then join to create a phylogenetic tree to determine which organisms have the closest connection to each other.

For a more precise and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to establish the connections between organisms. This information 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 determine the number of species who share a common ancestor and to estimate their evolutionary age.

Phylogenetic relationships can be affected by a variety of factors, including phenotypicplasticity. This is a type behaviour that can change as a result of particular environmental conditions. This can cause a particular trait to appear more like a species another, clouding the phylogenetic signal. However, this issue can be reduced by the use of techniques such as cladistics that include a mix of homologous and analogous features into the tree.

Additionally, phylogenetics can aid in predicting the time and 에볼루션 바카라 pace of speciation. This information will assist conservation biologists in making decisions about which species to save from disappearance. In the end, it is the preservation of phylogenetic diversity 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 based on their interactions with their environment. A variety of theories about evolution have been proposed by a wide variety of scientists, 에볼루션 게이밍 including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that could be passed on to offspring.

In the 1930s and 1940s, ideas from a variety of fields -- including genetics, natural selection, and particulate inheritance--came together to form the current synthesis of evolutionary theory that explains how evolution is triggered by the variations of genes within a population and how these variants change over time due to natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and can be mathematically described.

Recent advances in evolutionary developmental biology have shown how variation can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction and the movement between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of a genotype over time), can lead to 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 that genotype in the individual).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking into all areas of biology. In a recent study conducted by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution in the course of a college biology. To learn more about how to teach about evolution, read The Evolutionary Potential in 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 studying living organisms. Evolution isn't a flims event; it is a process that continues today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior because of a changing environment. The resulting changes are often easy to see.

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

In the past, if a certain allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could become more common than other allele. Over time, this would mean that the number of moths with black pigmentation in a population could increase. The same is true for 에볼루션 바카라 무료체험 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 generation turnover, as with bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from one strain. Samples from each population have been taken regularly, and more than 500.000 generations of E.coli have been observed to 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 shows that evolution takes time--a fact that many find difficult to accept.

Another example of microevolution is that mosquito genes that are resistant to pesticides are more prevalent in populations where insecticides are employed. This is because pesticides cause a selective pressure which favors those with resistant genotypes.

The speed at which evolution takes place has led to an increasing recognition of its importance in a world shaped by human activities, including climate change, 에볼루션 바카라 pollution and the loss of habitats that hinder many species from adapting. Understanding evolution can assist you in making better choices regarding the future of the planet and its inhabitants.