The Academy's Evolution Site
Biology is one of the most fundamental concepts in biology. The Academies are committed to helping those who are interested in science to learn about the theory of evolution and how it is incorporated in all areas of scientific research.
This site provides students, teachers and general readers with a range of learning resources about evolution. It contains key video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It appears in many spiritual traditions and cultures as symbolizing unity and love. It also has important practical applications, like providing a framework to understand the history of species and how they respond to changes in environmental conditions.
The first attempts to depict the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods, which rely on the sampling of different parts of living organisms or small DNA fragments, greatly increased the variety of organisms that could be represented in a tree of life2. The trees are mostly composed of eukaryotes, while bacteria are largely underrepresented3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular techniques, such as the small-subunit ribosomal gene.
The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much diversity to be discovered. This is particularly true of microorganisms that are difficult to cultivate and are usually only found in a single sample5. Recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a variety of archaea, bacteria, and other organisms that haven't yet been isolated, or whose diversity has not been thoroughly understood6.
This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine if certain habitats require special protection. This information can be utilized in a variety of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of the quality of crops. The information is also valuable in conservation efforts. It helps biologists discover areas most likely to have species that are cryptic, which could perform important metabolic functions and are susceptible to changes caused by humans. Although funds to protect biodiversity are essential, ultimately the best way to protect the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny (also known as an evolutionary tree) illustrates the relationship between different organisms. Utilizing molecular data similarities and differences in morphology, or ontogeny (the course of development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic categories. The role of phylogeny is crucial in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms with similar traits and evolved from a common ancestor. These shared traits can be either homologous or analogous. Homologous traits are similar in terms of their evolutionary journey. Analogous traits might appear similar, but they do not have the same ancestry. Scientists group similar traits into a grouping called a clade. For example, all of the species in a clade share the trait of having amniotic egg and evolved from a common ancestor who had eggs. A phylogenetic tree is then constructed by connecting the clades to identify the organisms that are most closely related to one another.
For a more detailed and accurate phylogenetic tree, scientists make use of molecular data from DNA or RNA to identify the connections between organisms. This information is more precise than morphological information and provides evidence of the evolution background of an organism or group. Researchers can utilize Molecular Data to estimate the evolutionary age of organisms and determine how many organisms share a common ancestor.
에볼루션 슬롯게임 of a species can be affected by a number of factors such as phenotypicplasticity. This is a type behavior that alters due to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another which can obscure the phylogenetic signal. However, this issue can be reduced by the use of methods such as cladistics which combine analogous and homologous features into the tree.
Additionally, phylogenetics can help determine the duration and rate of speciation. This information can help conservation biologists decide which species they should protect from extinction. In the end, it is the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms alter over time because of their interactions with their environment. Several theories of evolutionary change have been developed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that could be passed on to offspring.
In the 1930s and 1940s, ideas from various fields, including genetics, natural selection and particulate inheritance--came together to form the current evolutionary theory synthesis which explains how evolution occurs through the variations of genes within a population and how those variations change over time as a result of natural selection. This model, which encompasses genetic drift, mutations, gene flow and sexual selection, can be mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have shown that variations can be introduced into a species via genetic drift, mutation, and reshuffling genes during sexual reproduction, and also through the movement of populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution that is defined as changes in the genome of the species over time, and also by changes in phenotype over time (the expression of the genotype within the individual).
Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny as well as evolution. In a recent study by Grunspan et al. It was found that teaching students about the evidence for evolution increased their understanding of evolution during a college-level course in biology. To learn 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 into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution through looking back in the past, studying fossils, and comparing species. They also observe living organisms. But evolution isn't just something that happened in the past. It's an ongoing process that is that is taking place today. Bacteria transform and resist antibiotics, viruses reinvent themselves and elude new medications and animals change their behavior in response to the changing climate. The resulting changes are often easy to see.
It wasn't until the late 1980s when biologists began to realize that natural selection was also at work. The main reason is that different traits result in an individual rate of survival as well as reproduction, and may be passed on from generation to generation.
In the past, if one allele - the genetic sequence that determines colour was present in a population of organisms that interbred, it might become more prevalent than any other allele. As time passes, that could mean that the number of black moths in the 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 the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. Samples from each population have been taken frequently and more than 50,000 generations of E.coli have passed.
Lenski's research has revealed that mutations can alter the rate at which change occurs and the efficiency at which a population reproduces. It also demonstrates that evolution takes time, which is difficult for some to accept.
Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides have been used. Pesticides create a selective pressure which favors those with resistant genotypes.
The rapidity of evolution has led to an increasing appreciation of its importance especially in a planet which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding the evolution process can assist you in making better choices about the future of the planet and its inhabitants.