The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those who are interested in the sciences comprehend the evolution theory and how it is permeated across all areas of scientific research.
This site provides students, teachers and general readers with a range of learning resources about 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 practical uses, like providing a framework to understand the evolution of species and how they react to changing environmental conditions.
Early attempts to represent the biological world were built on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on sampling of different parts of living organisms or small DNA fragments, significantly increased the variety that could be included in the tree of life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.
Genetic techniques have significantly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques allow us to construct trees using sequenced markers such as the small subunit of ribosomal RNA gene.
The Tree of Life has been significantly expanded by genome sequencing. However there is a lot of diversity to be discovered. 에볼루션 무료 바카라 is especially true of microorganisms, which can be difficult to cultivate and are usually only represented in a single sample5. A recent analysis of all genomes has produced a rough draft of the Tree of Life. This includes a large number of archaea, bacteria and other organisms that haven't yet been isolated or the diversity of which is not fully understood6.
The expanded Tree of Life is particularly useful in assessing the diversity of an area, which can help to determine if specific habitats require special protection. This information can be utilized in many ways, including identifying new drugs, combating diseases and improving the quality of crops. This information is also extremely valuable in conservation efforts. It helps biologists discover areas that are most likely to be home to cryptic species, which may have important metabolic functions and are susceptible to human-induced change. Although funding to protect biodiversity are essential however, the most effective method to ensure the preservation of biodiversity around the world 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, shows the connections between various groups of organisms. Utilizing molecular data as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolution of taxonomic categories. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and have evolved from an ancestor with common traits. These shared traits may be analogous, or homologous. Homologous traits are similar in their evolutionary journey. Analogous traits might appear like they are, but they do not have the same ancestry. Scientists arrange similar traits into a grouping referred to as a the clade. For instance, all of the species in a clade share the trait of having amniotic egg and evolved from a common ancestor which had these eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms that are most closely related to each other.
Scientists make use of molecular DNA or RNA data to create a phylogenetic chart which is more precise and precise. This information is more precise than morphological information and provides evidence of the evolution history of an organism or group. Researchers can use Molecular Data to calculate the age of evolution of organisms and identify how many organisms share a common ancestor.
에볼루션 사이트 between species can be affected by a variety of factors including phenotypic plasticity, a kind of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more resembling to one species than to the other and obscure the phylogenetic signals. This issue can be cured by using cladistics, which incorporates a combination of homologous and analogous traits in the tree.
Additionally, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists in making choices about which species to safeguard from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their environments. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would evolve according to its individual requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can lead to changes that can be passed on to future generations.
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 happens through the variation of genes within a population and how those variations change over time as a result of natural selection. This model, which includes mutations, genetic drift as well as gene flow and sexual selection is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed how variations can be introduced to a species via genetic drift, mutations, reshuffling genes during sexual reproduction and migration between populations. These processes, along with others such as directionally-selected selection and erosion of genes (changes in 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 an individual).
Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny as well as evolution. In a recent study conducted by Grunspan et al., it was shown that teaching students about the evidence for evolution increased their understanding of evolution during the course of a college biology. To find out more about how to teach about evolution, please look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species and studying living organisms. Evolution isn't a flims moment; it is an ongoing process that continues to be observed today. Bacteria mutate and resist antibiotics, viruses reinvent themselves and escape new drugs and animals change their behavior to the changing environment. The results are often apparent.
It wasn't until the 1980s that biologists began realize that natural selection was in play. The main reason is that different traits can 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 color - was found in a group of organisms that interbred, it could be more prevalent than any other allele. As time passes, this could mean that the number of moths with black pigmentation may increase. 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 an organism, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from a single strain. Samples from each population were taken regularly, and more than 500.000 generations of E.coli have passed.
Lenski's work has demonstrated that a mutation can profoundly alter the efficiency with the rate at which a population reproduces, and consequently, the rate at which it evolves. It also shows that evolution takes time--a fact that many find difficult to accept.
Microevolution is also evident 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 who have resistant genotypes.
The rapidity of evolution has led to an increasing awareness of its significance especially in a planet that is largely shaped by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution will aid you in making better decisions about the future of the planet and its inhabitants.