The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those interested in the sciences comprehend the evolution theory and how it is permeated throughout all fields of scientific research.
This site provides a wide range of resources for teachers, students as well as general readers about evolution. It contains the most important video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of life. It is used in many religions and cultures as symbolizing unity and love. It also has important practical uses, like providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
Early attempts to describe the biological world were built on categorizing organisms based on their physical and metabolic characteristics. These methods, which depend on the sampling of different parts of organisms or DNA fragments, have greatly increased the diversity of a tree of Life2. These trees are largely composed by eukaryotes and bacteria are largely underrepresented3,4.
By avoiding the need for direct observation and experimentation, genetic techniques have enabled us to depict the Tree of Life in a more precise way. We can create trees by using molecular methods like 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 true for microorganisms that are difficult to cultivate and are usually only present in a single sample5. A recent analysis of all known genomes has produced a rough draft version of the Tree of Life, including a large number of bacteria and archaea that are not isolated and which are not well understood.
This expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if particular habitats need special protection. The information can be used in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crops. This information is also extremely valuable to conservation efforts. It can help biologists identify areas that are likely to be home to cryptic species, which could have important metabolic functions, and could be susceptible to the effects of human activity. While funding to protect biodiversity are important, the best method to protect the biodiversity of the world 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 connections between various groups of organisms. Scientists can construct a phylogenetic chart that shows the evolution of taxonomic groups using molecular data 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 with similar traits and evolved from an ancestor with common traits. These shared traits could be analogous or homologous. Homologous characteristics are identical in their evolutionary journey. Analogous traits could appear like they are, but they do not have the same ancestry. Scientists arrange similar traits into a grouping referred to as a clade. All organisms in a group share a trait, such as amniotic egg production. They all derived from an ancestor with these eggs. A phylogenetic tree can be constructed by connecting clades to determine the organisms who are the closest to one another.
Scientists make use of DNA or RNA molecular information to construct a phylogenetic graph which is more precise and precise. This information is more precise than the morphological data and provides evidence of the evolutionary background of an organism or group. The use of molecular data lets researchers determine the number of organisms that have an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic flexibility, an aspect of behavior that alters in response to specific environmental conditions. This can make a trait appear more resembling to one species than to another, obscuring the phylogenetic signals. However, this problem can be solved through the use of methods such as cladistics that combine homologous and analogous features into the tree.
Additionally, phylogenetics aids determine the duration and speed of speciation. This information can aid conservation biologists in making decisions about which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme of evolution is that organisms acquire various characteristics over time as a result of their interactions with their environments. Several theories of evolutionary change have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve gradually according to its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who conceived modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that can be passed onto offspring.
In the 1930s and 1940s, theories from various areas, including genetics, natural selection and particulate inheritance, merged to form a contemporary evolutionary theory. This describes how evolution occurs by the variation of genes in the population and how these variations change with time due to natural selection. This model, which is known as genetic drift mutation, gene flow and sexual selection, is a key element of current evolutionary biology, and is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species through mutation, genetic drift, and reshuffling of genes in sexual reproduction, and also through the movement of populations. These processes, along with others such as directionally-selected selection and erosion of genes (changes in the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time as well as changes in phenotype (the expression of genotypes in individuals).
Students can better understand the concept of phylogeny by using evolutionary thinking into all areas of biology. 에볼루션 바카라사이트 by Grunspan and colleagues, for example, showed that teaching about the evidence supporting evolution increased students' understanding of evolution in a college biology course. For more information on how to teach evolution, see The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species and studying living organisms. Evolution is not a past moment; it is a process that continues today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and escape new drugs and animals alter their behavior to the changing environment. The changes that result are often visible.
However, it wasn't until late 1980s that biologists realized that natural selection could be seen in action, as well. The key is the fact that different traits confer an individual rate of survival and reproduction, and they can be passed down from generation to generation.
In the past, if an allele - the genetic sequence that determines colour was present in a population of organisms that interbred, it could become more common than other allele. As time passes, this could mean that the number of moths sporting black pigmentation in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Monitoring evolutionary changes in action is easier when a particular species has a fast generation turnover like bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each are taken every day and more than fifty thousand generations have been observed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the efficiency of a population's reproduction. It also demonstrates that evolution takes time, which is difficult for some to accept.
에볼루션 바카라사이트 of microevolution is that mosquito genes that confer resistance to pesticides show up more often in areas where insecticides are used. This is due to the fact that the use of pesticides creates a pressure that favors people who have resistant genotypes.
The rapidity of evolution has led to an increasing appreciation of its importance, especially in a world that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding the evolution process will help us make better choices about the future of our planet and the lives of its inhabitants.