The Academy's Evolution Site
Biological evolution is one of the most central concepts in biology. The Academies are involved in helping those interested in science understand evolution theory and how it is permeated in all areas of scientific research.
This site provides a range of sources for students, teachers, and general readers on evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is seen in a variety of spiritual traditions and cultures as a symbol of unity and love. It also has important practical applications, such as providing a framework for understanding the history of species and how they respond to changes in environmental conditions.
The earliest attempts to depict the biological world focused on the classification of organisms into distinct categories which were distinguished by physical and metabolic characteristics1. These methods, which depend on the collection of various parts of organisms, or fragments of DNA, have significantly increased the diversity of a Tree of Life2. However, these trees are largely comprised of eukaryotes, and bacterial diversity is not represented in a large way3,4.
By avoiding the necessity for direct observation and experimentation, genetic techniques have allowed us to depict the Tree of Life in a much more accurate way. Trees can be constructed using molecular techniques such as the small subunit ribosomal gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true of microorganisms that are difficult to cultivate and are typically only found in a single specimen5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including numerous bacteria and archaea that are not isolated and their diversity is not fully understood6.
This expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if certain habitats require special protection. This information can be used in a variety of ways, such as finding new drugs, battling diseases and improving crops. The information is also incredibly beneficial to conservation efforts. It can aid biologists in identifying areas that are most likely to be home to cryptic species, which may have vital metabolic functions and are susceptible to the effects of human activity. While funding to protect biodiversity are essential, the best method to preserve the world's biodiversity is to equip more people in developing nations with the necessary knowledge to take action locally and encourage conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, shows the connections between different groups of organisms. By using molecular information, morphological similarities and differences or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree which illustrates the evolutionary relationship between taxonomic categories. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and have evolved from a common ancestor. These shared traits are either homologous or analogous. Homologous characteristics are identical in their evolutionary paths. Analogous traits might appear like they are, but they do not have the same origins. Scientists combine similar traits into a grouping referred to as a 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 eggs. A phylogenetic tree can be constructed by connecting clades to determine the organisms that are most closely related to one another.
To create a more thorough and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to identify the relationships between organisms. This information is more precise and gives evidence of the evolution history of an organism. The analysis of molecular data can help researchers determine the number of species that share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships of a species can be affected by a variety of factors, including phenotypicplasticity. This is a kind of behavior that changes due to particular environmental conditions. 에볼루션 게이밍 can cause a trait to appear more similar to one species than to another and obscure the phylogenetic signals. This problem can be mitigated by using cladistics. This is a method that incorporates a combination of homologous and analogous features in the tree.
Additionally, phylogenetics aids determine the duration and speed at which speciation occurs. This information can aid conservation biologists to make decisions about which species they should protect from extinction. In the end, it is the preservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme in evolution is that organisms change over time as a result of 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 would develop according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of traits can cause changes that are passed on to the next generation.
In the 1930s and 1940s, ideas from a variety of fields--including natural selection, genetics, and particulate inheritance--came together to form the modern synthesis of evolutionary theory, which defines how evolution happens through the variation of genes within a population and how these variants change in time as a result of natural selection. This model, which encompasses genetic drift, mutations in gene flow, and sexual selection can be mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that variation can be introduced into a species by mutation, genetic drift, and reshuffling of genes during sexual reproduction, as well as by migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time) can lead to evolution, which is defined by 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).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. In a study by Grunspan and colleagues. It was found that teaching students about the evidence for evolution boosted their understanding of evolution during an undergraduate biology course. For more information on how to teach evolution read The Evolutionary Potency in all Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have looked at evolution through the past--analyzing fossils and comparing species. They also observe living organisms. But evolution isn't a thing that happened in the past; it's an ongoing process, taking place in the present. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of the changing environment. 에볼루션 무료체험 that result are often evident.
It wasn't until late 1980s when biologists began to realize that natural selection was also in action. The key to this is that different traits can confer an individual rate of survival and reproduction, and can be passed on from one generation to another.
In the past, if one particular allele, the genetic sequence that defines color in a population of interbreeding organisms, it might quickly become more prevalent than all other alleles. As time passes, this could mean that the number of moths with 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 much easier when a species has a rapid generation turnover, as with bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. Samples from each population have been collected regularly, and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's research has revealed that a mutation can dramatically alter the efficiency with the rate at which a population reproduces, and consequently, the rate at which it evolves. It also proves that evolution is slow-moving, a fact that some are unable to accept.
Another example of microevolution is how mosquito genes that are resistant to pesticides show up more often in areas where insecticides are employed. This is due to the fact that the use of pesticides creates a selective pressure that favors individuals with resistant genotypes.
The speed at which evolution can take place has led to a growing appreciation of its importance in a world that is shaped by human activities, including climate change, pollution and the loss of habitats that hinder many species from adjusting. Understanding the evolution process can help you make better decisions about the future of the planet and its inhabitants.