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The Academy's Evolution Site

Biology is a key concept in biology. The Academies have long been involved in helping those interested in science understand the theory of evolution and how it influences all areas of scientific exploration.

This site provides students, teachers and general readers with a range of learning resources about evolution. It includes key video clip 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 an emblem of love and unity in many cultures. It can be used in many practical ways as well, including providing a framework to understand the history of species, and how they react to changing environmental conditions.

The earliest attempts to depict the world of biology focused on categorizing organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, which are based on the sampling of different parts of organisms or short DNA fragments have significantly increased the diversity of a tree of Life2. These trees are largely composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

Genetic techniques have greatly broadened our ability to depict 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 a lot of biodiversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate and are typically found in one sample5. A recent analysis of all genomes has produced a rough draft of the Tree of Life. This includes a large number of archaea, bacteria and other organisms that haven't yet been isolated, or whose diversity has not been well understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine if specific habitats require protection. This information can be used in a range of ways, from identifying new remedies to fight diseases to improving crops. This information is also extremely useful in conservation efforts. It can aid biologists in identifying areas that are likely to be home to species that are cryptic, which could have vital metabolic functions and be vulnerable to changes caused by humans. While funds to protect biodiversity are essential, the best method to protect the biodiversity of the world is to equip more people in developing countries with the necessary knowledge to act locally and promote conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) shows the relationships between different organisms. Scientists can construct a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny is essential in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestral. These shared traits can be either homologous or analogous. Homologous traits are identical in their underlying evolutionary path while analogous traits appear like they do, but don't have the identical origins. Scientists arrange similar traits into a grouping referred to as a Clade. All organisms in a group share a characteristic, 에볼루션 카지노 사이트 for example, amniotic egg production. They all evolved from an ancestor that had these eggs. A phylogenetic tree can be constructed by connecting the clades to identify the species who are the closest to one another.

Scientists use DNA or 무료 에볼루션, Recommended Reading, RNA molecular information to create 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. Molecular data allows researchers to identify the number of organisms that have an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationship can be affected by a number of factors, including the phenotypic plasticity. This is a type behaviour that can change due to specific environmental conditions. This can cause a characteristic to appear more similar in one species than another, clouding the phylogenetic signal. However, this issue can be cured by the use of methods such as cladistics which include a mix of homologous and analogous features into the tree.

In addition, phylogenetics can help predict the duration and rate of speciation. This information will assist conservation biologists in deciding which species to save from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism 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 suggested that the use or absence of traits can lead to changes that are passed on to the next generation.

In the 1930s & 1940s, concepts from various fields, such as natural selection, genetics & particulate inheritance, merged to form a contemporary theorizing of evolution. This describes how evolution happens through the variation of genes in the population and how these variants alter over time due to natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is a cornerstone of modern evolutionary biology and is mathematically described.

Recent advances in evolutionary developmental biology have revealed how variation can be introduced to a species by genetic drift, mutations or reshuffling of genes in sexual reproduction and the movement between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of the genotype over time) can lead to evolution, which is defined by changes in the genome of the species over time, and also the change in phenotype over time (the expression of that genotype in an individual).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking throughout all areas of biology. In a study by Grunspan et al. It was found that teaching students about the evidence for evolution increased their acceptance of evolution during a college-level course in biology. For more information on how to teach about evolution look up The Evolutionary Power of Biology 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 by looking back, studying fossils, comparing species, and studying living organisms. Evolution is not a distant event; it is a process that continues today. Bacteria mutate and resist antibiotics, viruses evolve and are able to evade new medications and animals change their behavior to the changing climate. The resulting changes are often visible.

However, it wasn't until late 1980s that biologists understood that natural selection could be seen in action, as well. The key is that different 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 one particular allele - the genetic sequence that defines color in a group of interbreeding organisms, it might quickly become more common than other alleles. 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.

Observing evolutionary change in action is easier when a particular species has a rapid generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from a single strain. Samples of each population have been taken frequently and more than 500.000 generations of E.coli have passed.

Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the efficiency at which a population reproduces. It also proves that evolution takes time--a fact that some find hard to accept.

Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in areas where insecticides have been used. This is due to pesticides causing an exclusive pressure 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 climate change, pollution, 무료 에볼루션 and habitat loss that prevents many species from adapting. Understanding the evolution process can help us make smarter decisions regarding the future of our planet, 에볼루션 무료 바카라 as well as the lives of its inhabitants.