Are You Getting The Most Value You Evolution Site?
The Academy's Evolution Site
Biological evolution is one of the most central concepts in biology. The Academies are committed to helping those interested in science to understand evolution theory and how it can be applied throughout all fields of scientific research.
This site offers a variety of sources for teachers, students and general readers of 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 unity in many cultures. It has numerous practical applications as well, including providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
The earliest attempts to depict the world of biology focused on the classification of species into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods rely on the sampling of different parts of organisms, or DNA fragments, have significantly increased the diversity of a tree of Life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4.
In avoiding the necessity of direct observation and experimentation, genetic techniques have made it possible to depict the Tree of Life in a much more accurate way. Trees can be constructed by using molecular methods such as the small subunit ribosomal gene.
The Tree of Life has been significantly expanded by genome sequencing. However, there is still much biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are typically found in one sample5. A recent analysis of all genomes that are known has created a rough draft of the Tree of Life, including a large number of archaea and bacteria that are not isolated and their diversity is not fully understood6.
The expanded Tree of Life can be used to determine the diversity of a particular area and determine if certain habitats require special protection. This information can be utilized in a variety of ways, from identifying new medicines to combating disease to enhancing crop yields. This information is also extremely beneficial to conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species with significant metabolic functions that could be at risk of anthropogenic changes. While 에볼루션코리아 are important, the most effective way to conserve the world's biodiversity is to empower more people in developing nations with the information they require to take action locally and encourage conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) illustrates the relationship between organisms. Scientists can construct a phylogenetic chart that shows the evolutionary relationships between taxonomic categories using molecular information and morphological similarities or differences. Phylogeny is essential in understanding evolution, biodiversity and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestors. These shared traits can be either analogous or homologous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear similar but do not have the same ancestors. Scientists put similar traits into a grouping known as a Clade. All members of a clade share a characteristic, like amniotic egg production. They all evolved from an ancestor who had these eggs. The clades are then connected to form a phylogenetic branch to determine the organisms with the closest connection to each other.
Scientists make use of DNA or RNA molecular data to build a phylogenetic chart that is more precise and detailed. This information is more precise and provides evidence of the evolution history of an organism. The use of molecular data lets researchers identify the number of species that share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships between organisms can be influenced by several factors including phenotypic plasticity, an aspect of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than another and obscure the phylogenetic signals. However, this issue can be reduced by the use of methods such as cladistics that incorporate a combination of homologous and analogous features into the tree.
Furthermore, phylogenetics may aid in predicting the duration and rate of speciation. This information will assist conservation biologists in making decisions about which species to safeguard from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme of evolution is that organisms develop different features over time based on their interactions with their surroundings. Many theories of evolution have been developed by a variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that could be passed on to the offspring.
In the 1930s and 1940s, theories from a variety of fields--including natural selection, genetics, and particulate inheritance - came together to form the modern evolutionary theory synthesis which explains how evolution happens through the variations of genes within a population and how these variants change in time as a result of natural selection. This model, which is known as genetic drift, mutation, gene flow and sexual selection, is the foundation of modern evolutionary biology and can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species via genetic drift, mutation, and reshuffling of genes in sexual reproduction, and also through migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution which is defined by changes in the genome of the species over time and the change in phenotype as time passes (the expression of that genotype in an individual).
Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny as well as evolution. In a study by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution boosted their understanding of evolution during the course of a college biology. To learn more about how to teach about evolution, see The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution by looking in the past, analyzing fossils and comparing species. They also study living organisms. Evolution is not a distant event, but an ongoing process. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior because of a changing environment. The changes that result are often easy to see.
But it wasn't until the late-1980s that biologists realized that natural selection could be seen in action, as well. The key is the fact that different traits confer a different rate of survival and reproduction, and they can be passed down from one generation to another.
In the past, if one particular allele, the genetic sequence that defines color in a group of interbreeding species, it could rapidly become more common than the other alleles. In time, this could mean that the number of moths that have 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.
Monitoring evolutionary changes in action is easier when a particular species has a rapid turnover of its generation such as bacteria. 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 on a regular basis and more than fifty thousand generations have been observed.
Lenski's research has revealed that mutations can alter the rate of change and the efficiency of a population's reproduction. It also demonstrates that evolution takes time, a fact that is hard for some to accept.
Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more common in populations where insecticides are used. This is because the use of pesticides creates a selective pressure that favors those with resistant genotypes.
The rapid pace at which evolution can take place has led to an increasing appreciation of its importance in a world shaped by human activities, including climate change, pollution, and the loss of habitats which prevent the species from adapting. Understanding evolution can help us make better decisions about the future of our planet and the life of its inhabitants.