The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies have long been involved in helping people who are interested in science comprehend the theory of evolution and how it permeates all areas of scientific research.
This site provides a range of tools for students, teachers, and general readers on evolution. It has 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 an emblem of love and harmony in a variety of cultures. It also has many practical applications, such as 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 categorizing organisms into distinct categories that were distinguished by physical and metabolic characteristics1. These methods, based on the sampling of different parts of living organisms or on sequences of small fragments of their DNA significantly increased the variety that could be represented in a tree of life2. These trees are largely composed by eukaryotes and bacterial diversity is vastly underrepresented3,4.
Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to construct trees by using sequenced markers, such as the small subunit ribosomal RNA gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However, there is still much diversity to be discovered. This is particularly true for microorganisms, which can be difficult to cultivate and are typically only found in a single sample5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including a large number of archaea and bacteria that have not been isolated, and which are not well understood.
The expanded Tree of Life can be used to determine the diversity of a specific area and determine if particular habitats require special protection. This information can be utilized in a range of ways, from identifying new treatments to fight disease to enhancing crop yields. The information is also incredibly beneficial to conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species with potentially important metabolic functions that could be vulnerable to anthropogenic change. While funds to protect biodiversity are essential, the best method to protect the world's biodiversity is to equip more people in developing nations with the knowledge they need to act locally and promote conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) depicts the relationships between species. Using molecular data as well as morphological similarities and distinctions or ontogeny (the course of development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolution of taxonomic groups. Phylogeny is essential in understanding biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that have evolved from common ancestral. These shared traits could be either homologous or analogous. Homologous traits are identical in their underlying evolutionary path, while analogous traits look similar, but do not share the identical origins. Scientists group similar traits together into a grouping known as a the clade. For example, all of the organisms that make up a clade share the characteristic of having amniotic eggs and evolved from a common ancestor who had these eggs. 에볼루션 무료 바카라 is constructed by connecting the clades to identify the species which are the closest to each other.
To create a more thorough and accurate phylogenetic tree, scientists use molecular data from DNA or RNA to identify the connections between organisms. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to calculate the age of evolution of organisms and determine how many organisms have an ancestor common to all.
The phylogenetic relationships between organisms are influenced by many factors including phenotypic plasticity, a type of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more similar to one species than other species, which can obscure the phylogenetic signal. However, this issue can be reduced by the use of techniques like cladistics, which incorporate a combination of analogous and homologous features into the tree.
Additionally, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists decide which species to protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.
Evolutionary Theory
The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Several theories of evolutionary change have been proposed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause 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 which explains how evolution happens through the variations of genes within a population and how those variations change in time due to natural selection. This model, which incorporates mutations, genetic drift, gene flow and sexual selection, can be mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have revealed that variations can be introduced into a species via mutation, genetic drift, and reshuffling genes during sexual reproduction, and also through the movement of populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can lead to evolution which is defined by changes in the genome of the species over time, and the change in phenotype over time (the expression of that genotype within the individual).
Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny as well as evolution. A recent study conducted by Grunspan and colleagues, for instance demonstrated that teaching about the evidence supporting evolution increased students' understanding of evolution in a college biology class. For more details on how to teach evolution, see The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily: a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past, analyzing fossils and comparing species. They also study living organisms. However, evolution isn't something that occurred in the past; it's an ongoing process that is happening right now. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of a changing world. The changes that occur are often visible.
It wasn't until late 1980s that biologists realized that natural selection can be observed in action as well. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.
In the past, if a certain allele - the genetic sequence that determines color - was found in a group of organisms that interbred, it might become more prevalent than any other allele. In time, 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.
It is easier to track evolutionary change 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 one strain. The samples of each population were taken regularly and more than 50,000 generations of E.coli have passed.
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, something that is hard for some to accept.
Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more prevalent in areas where insecticides have been used. This is due to pesticides causing an exclusive pressure that favors individuals who have resistant genotypes.
에볼루션사이트 at which evolution can take place has led to a growing recognition 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 assist you in making better choices about the future of our planet and its inhabitants.