에볼루션 게이밍 is one of the most central concepts in biology. The Academies are committed to helping those who are interested in science to learn about the theory of evolution and how it is incorporated across all areas of scientific research.
This site offers a variety of resources for teachers, students as well as general readers about evolution. It includes important video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is seen in a variety of spiritual traditions and cultures as symbolizing unity and love. It also has many practical applications, like providing a framework for understanding the evolution of species and how they react to changing environmental conditions.
The first attempts at depicting the world of biology focused on separating organisms into distinct categories which had been distinguished by their physical and metabolic characteristics1. These methods, which are based on the sampling of different parts of organisms or DNA fragments, have significantly increased the diversity of a Tree of Life2. However the trees are mostly made up of eukaryotes. Bacterial diversity remains 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. Trees can be constructed using molecular techniques, such as 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 true for microorganisms that are difficult to cultivate, and are usually found in a single specimen5. A recent analysis of all known genomes 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 whose diversity is poorly understood6.
This expanded Tree of Life can be used to determine the diversity of a specific region and determine if certain habitats require special protection. The information is useful in many ways, including finding new drugs, fighting diseases and improving crops. The information is also incredibly useful in conservation efforts. It can help biologists identify the areas most likely to contain cryptic species with important metabolic functions that could be at risk of anthropogenic changes. Although funding to safeguard biodiversity are vital however, the most effective method to preserve the world's biodiversity is for more people in developing countries to be equipped with the knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between organisms. Scientists can build a phylogenetic chart that shows the evolution of taxonomic groups based on molecular data and morphological similarities or differences. The role of phylogeny is crucial in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from an ancestor with common traits. These shared traits are either homologous or analogous. Homologous traits are similar in their evolutionary origins and analogous traits appear like they do, but don't have the identical origins. Scientists put similar traits into a grouping called a Clade. All organisms in a group share a characteristic, like amniotic egg production. They all evolved from an ancestor that had these eggs. The clades are then connected to form a phylogenetic branch that can determine which organisms have the closest relationship.
For 에볼루션 바카라 무료 detailed and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to determine the relationships between organisms. This information is more precise and provides evidence of the evolution of an organism. The use of molecular data lets researchers determine the number of organisms that have a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships of organisms can be affected by a variety of factors, including phenotypic flexibility, an aspect of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar in one species than another, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which incorporates the combination of analogous and homologous features in the tree.
In addition, phylogenetics helps predict the duration and rate at which speciation takes place. This information can assist conservation biologists decide which species they should protect from the threat of extinction. In the end, it is the preservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms develop distinct characteristics over time as a result of their interactions with their surroundings. 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 develop according to its own needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of certain traits can result in changes that are passed on to the next generation.
In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance - came together to create the modern synthesis of evolutionary theory that explains how evolution occurs through the variation of genes within a population, and how these variants change over time due to natural selection. This model, which incorporates genetic drift, mutations in gene flow, and sexual selection, can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have shown that variations can be introduced into a species by mutation, genetic drift, and reshuffling of genes in sexual reproduction, and also through the movement of populations. These processes, in conjunction with others such as the directional selection process and the erosion of genes (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time as well as changes in phenotype (the expression of genotypes in individuals).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. A recent study by Grunspan and colleagues, for instance revealed that teaching students about the evidence that supports evolution helped students accept the concept of evolution in a college biology course. For more details on how to teach about evolution read The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution through looking back in the past, studying fossils, and comparing species. They also observe living organisms. Evolution is not a distant event, but an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, viruses reinvent themselves and elude new medications and animals change their behavior in response to a changing planet. The changes that occur are often apparent.
It wasn't until late 1980s that biologists realized that natural selection can be observed in action as well. The key to this is that different traits result in an individual rate of survival and reproduction, and they can be passed down from one generation to the next.
In the past, when one particular allele, the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it could quickly become more prevalent than all other alleles. In time, this could mean the number of black moths within a particular population could rise. 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 the species, like 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 from each population are taken on a regular basis and over 500.000 generations have been observed.
Lenski's work has demonstrated that a mutation can dramatically alter the efficiency with the rate at which a population reproduces, and consequently, the rate at which it evolves. It also demonstrates that evolution takes time, a fact that is hard for some to accept.
Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more common in populations that have used insecticides. This is because pesticides cause a selective pressure which favors those with resistant genotypes.
The rapidity of evolution has led to a growing awareness of its significance particularly in a world that is largely shaped by human activity. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding the evolution process can help us make better choices about the future of our planet and the lives of its inhabitants.