The Academy's Evolution Site
The concept of biological evolution is among the most central concepts in biology. The Academies have been active for a long time in helping people who are interested in science comprehend the theory of evolution and how it permeates every area of scientific inquiry.
This site offers a variety of tools 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 also has many practical uses, like providing a framework for understanding the evolution of species and how they react to changing environmental conditions.
Early attempts to describe 에볼루션 블랙잭 were based on categorizing organisms based on their metabolic and physical characteristics. These methods, based on the sampling of various parts of living organisms or sequences of small fragments of their DNA, greatly increased the variety of organisms that could be included in a tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.
Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Trees can be constructed by using molecular methods, such as the small-subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of diversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are typically only present in a single specimen5. A recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a variety of bacteria, archaea and other organisms that haven't yet been identified or whose diversity has not been thoroughly 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 a variety of ways, including finding new drugs, battling diseases and improving the quality of crops. It is also valuable for conservation efforts. It can aid biologists in identifying areas that are most likely to be home to species that are cryptic, which could perform important metabolic functions and are susceptible to the effects of human activity. While funds to protect biodiversity are essential but the most effective way to ensure the preservation of biodiversity around the world is for more people living in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny (also called an evolutionary tree) shows the relationships between different organisms. Scientists can build a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic groups using molecular data and morphological similarities or differences. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and have evolved from an ancestor that shared traits. These shared traits may be analogous or homologous. Homologous characteristics are identical in terms of their evolutionary path. Analogous traits might appear like they are but they don't have the same origins. Scientists organize similar traits into a grouping called a the clade. Every organism in a group share a characteristic, for example, amniotic egg production. They all came from an ancestor who had these eggs. A phylogenetic tree can be built by connecting the clades to determine the organisms which are the closest to each other.
Scientists use DNA or RNA molecular data to build a phylogenetic chart that is more accurate and detailed. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to calculate the evolutionary age of living organisms and discover the number of organisms that have the same ancestor.
The phylogenetic relationships between organisms are influenced by many factors including phenotypic plasticity, 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 the other, obscuring the phylogenetic signals. This issue can be cured by using cladistics. This is a method that incorporates a combination of analogous and homologous features in the tree.
In addition, phylogenetics helps determine the duration and speed of speciation. This information can assist conservation biologists in deciding which species to safeguard from disappearance. In the end, it is the conservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms change over time due to their interactions with their environment. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived 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 can be passed on to future generations.
In the 1930s & 1940s, theories from various areas, including genetics, natural selection, and particulate inheritance, came together to form a modern theorizing of evolution. This defines how evolution is triggered by the variation in genes within the population and how these variants change with time due to natural selection. This model, which is known as genetic drift, mutation, gene flow and sexual selection, is a cornerstone of the current evolutionary biology and is mathematically described.
Recent advances in evolutionary developmental biology have shown how variation can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction, and even migration between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time), can lead to evolution that is defined as change in the genome of the species over time and the change in phenotype over time (the expression of that genotype in the individual).
Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny and evolutionary. In a study by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. For more information on how to teach about evolution, see The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution by looking in the past--analyzing fossils and comparing species. They also observe living organisms. However, evolution isn't something that occurred in the past, it's an ongoing process that is happening right now. Bacteria evolve and resist antibiotics, viruses reinvent themselves and escape new drugs, and animals adapt their behavior to a changing planet. The changes that occur are often apparent.
It wasn't until the 1980s that biologists began realize that natural selection was also in play. The key is the fact that different traits confer a different rate of survival and reproduction, and they can be passed down from generation to generation.
In the past, if one particular allele - the genetic sequence that defines color in a population of interbreeding species, it could quickly become more prevalent than the other alleles. As time passes, that 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.
The ability to observe evolutionary change is much easier when a species has a fast generation turnover, as with bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain. samples of each population are taken regularly and more than 500.000 generations have passed.
Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the effectiveness of a population's reproduction. It also shows that evolution is slow-moving, a fact that many are unable to accept.
Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more prevalent in populations where insecticides have been used. That's because the use of pesticides creates a selective pressure that favors those with resistant genotypes.
The rapid pace at which evolution takes place has led to a growing appreciation of its importance in a world that is shaped by human activities, including climate changes, pollution and the loss of habitats that prevent many species from adjusting. Understanding the evolution process will assist you in making better choices about the future of our planet and its inhabitants.