The Academy's Evolution Site
Biology is a key concept in biology. The Academies have long been involved in helping people who are interested in science understand the theory of evolution and how it permeates every area of scientific inquiry.
에볼루션 슬롯게임 offers a variety of sources for teachers, students and general readers of 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, symbolizes the interconnectedness of all life. It is seen in a variety of cultures and spiritual beliefs as an emblem of unity and love. It can be used in many practical ways as well, such as providing a framework for understanding the history of species, and how they react to changes in environmental conditions.
Early attempts to represent the biological world 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 sequences of short DNA fragments, significantly increased the variety that could be represented in a tree of life2. However the trees are mostly comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4.
By avoiding the necessity for direct observation and experimentation genetic techniques have allowed us to represent the Tree of Life in a more precise manner. In particular, molecular methods allow us to build trees by using sequenced markers 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 diversity to be discovered. This is particularly true for microorganisms, which are difficult to cultivate and are typically only found in a single specimen5. Recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a wide range of archaea, bacteria and other organisms that have not yet been isolated or whose diversity has not been fully understood6.
The expanded Tree of Life can be used to determine the diversity of a particular area and determine if particular habitats require special protection. This information can be utilized in a variety of ways, from identifying new remedies to fight diseases to improving the quality of crops. The information is also valuable in conservation efforts. It helps biologists discover areas that are likely to be home to cryptic species, which could have vital metabolic functions and are susceptible to the effects of human activity. While conservation funds are important, the best method to preserve the world's biodiversity is to equip more people in developing countries with the necessary knowledge to take action locally and encourage conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) illustrates the relationship between organisms. Using molecular data as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism) scientists can create a phylogenetic tree which illustrates the evolutionary relationship between taxonomic categories. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships 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 evolutionary roots and analogous traits appear similar but do not have the same origins. Scientists organize 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 evolved from an ancestor that had these eggs. A phylogenetic tree is then constructed by connecting the clades to identify the organisms that are most closely related to one another.
Scientists make use of DNA or RNA molecular data to construct a phylogenetic graph that is more accurate and precise. This information is more precise than morphological data and provides evidence of the evolution history of an individual or group. Molecular data allows researchers to identify the number of species that have the same ancestor and estimate their evolutionary age.
The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, a type of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more resembling to one species than to another which can obscure the phylogenetic signal. This issue can be cured by using cladistics, which is a the combination of homologous and analogous features in the tree.
In addition, phylogenetics can help predict the time and pace of speciation. This information can assist conservation biologists decide the species they should safeguard from the threat of extinction. In the end, it's the conservation of phylogenetic variety that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms acquire various characteristics over time as a result of their interactions with their surroundings. Several theories of evolutionary change have been developed by a wide variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop gradually according to its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits causes changes that can be passed on to offspring.
In the 1930s and 1940s, ideas from various fields, including genetics, natural selection, and particulate inheritance--came together to create the modern synthesis of evolutionary theory, which defines how evolution happens through the variation of genes within a population, and how these variants change over time as a result of natural selection. This model, which incorporates genetic drift, mutations, gene flow and sexual selection, can be mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have revealed that variation can be introduced into a species through genetic drift, mutation, and reshuffling of genes in sexual reproduction, and also by migration between populations. These processes, in conjunction with others, such as directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time and changes in the phenotype (the expression of genotypes in an individual).
Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny and evolution. In a study by Grunspan and colleagues. It was found that teaching students about the evidence for evolution boosted their understanding of evolution in the course of a college biology. For more details on how to teach about evolution read The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through studying fossils, comparing species, and observing living organisms. But evolution isn't a thing that happened in the past; it's an ongoing process that is that is taking place in the present. Viruses reinvent themselves to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior because of the changing environment. The changes that occur are often apparent.
It wasn't until late 1980s that biologists began realize that natural selection was at work. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.
In the past when one particular allele, the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it might rapidly become more common than all other alleles. As time passes, that could mean that the number of black moths in the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to track evolution when the species, like bacteria, has a high generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain. samples of each population are taken every day and over fifty thousand generations have been observed.
Lenski's work has demonstrated that a mutation can profoundly alter the efficiency with which a population reproduces and, consequently the rate at which it changes. It also proves that evolution is slow-moving, a fact that some people are unable to accept.
Another example of microevolution is how mosquito genes that confer resistance to pesticides appear more frequently in areas where insecticides are used. This is because pesticides cause a selective pressure which favors individuals who have resistant genotypes.
The rapidity of evolution has led to a growing appreciation of its importance particularly in a world which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding evolution will help you make better decisions about the future of our planet and its inhabitants.