The Academy's Evolution Site
Biological evolution is one of the most important concepts in biology. The Academies are committed to helping those interested in the sciences understand evolution theory and how it is permeated throughout all fields of scientific research.
This site offers a variety of tools for teachers, students and general readers of evolution. It includes important video clips from NOVA and WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of all life. It appears in many spiritual traditions and cultures as an emblem of unity and love. It also has practical applications, such as providing a framework for understanding the evolution of species and how they react to changes in the environment.
The earliest attempts to depict the biological world focused on the classification of organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, which depend on the collection of various parts of organisms, or fragments of DNA have greatly increased the diversity of a tree of Life2. However the trees are mostly made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.
By avoiding the need for direct experimentation and observation, genetic techniques have made it possible to depict the Tree of Life in a more precise way. We can create trees using molecular techniques, such as the small-subunit ribosomal 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 are difficult to cultivate and are usually only represented in a single sample5. A recent analysis of all genomes that are known has produced a rough draft version of the Tree of Life, including many archaea and bacteria that have not been isolated, and their diversity is not fully understood6.
The expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if certain habitats need special protection. This information can be used in a variety of ways, from identifying new treatments to fight disease to improving crops. The information is also beneficial in conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with important metabolic functions that may be at risk from anthropogenic change. While conservation funds are important, the best method to protect the world's biodiversity is to empower more people in developing countries with the information they require to act locally and support conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, shows the relationships between groups of organisms. Using molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolutionary relationship between taxonomic groups. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms with similar characteristics and have evolved from a common ancestor. These shared traits could be either homologous or analogous. Homologous traits are the same in their evolutionary journey. Analogous traits could appear similar, but they do not share the same origins. Scientists organize similar traits into a grouping referred to as a the clade. All members of a clade share a trait, such as amniotic egg production. 에볼루션 사이트 came from an ancestor that had these eggs. The clades then join to form a phylogenetic branch that can identify organisms that have the closest relationship to.
Scientists utilize molecular DNA or RNA data to construct a phylogenetic graph which is more precise and precise. This information is more precise and provides evidence of the evolution of an organism. Molecular data allows researchers to determine the number of species who share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic plasticity an aspect of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar in one species than another, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which is a an amalgamation of homologous and analogous traits in the tree.
Additionally, phylogenetics aids determine the duration and rate at which speciation takes place. This information can assist conservation biologists in making decisions about which species to save from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which will result in a complete and balanced ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms alter over time because of their interactions with their environment. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would develop according to its own requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of certain traits can result in changes that can be passed on to future generations.
In the 1930s & 1940s, concepts from various areas, including natural selection, genetics & particulate inheritance, came together to form a contemporary theorizing of evolution. This explains how evolution is triggered by the variations in genes within a population and how these variants change over time as a result of 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 demonstrated that variations can be introduced into a species by mutation, genetic drift and reshuffling of genes in sexual reproduction, and also through the movement of populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of the genotype over time) can result in evolution, which is defined by changes in the genome of the species over time, and also the change in phenotype as time passes (the expression of that genotype in an individual).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. In a recent study conducted by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution increased their acceptance of evolution during an undergraduate biology course. To learn more about how to teach about evolution, read The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past, studying fossils, and comparing species. They also study living organisms. Evolution is not a past moment; it is an ongoing process that continues to be observed today. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior in the wake of the changing environment. The resulting changes are often evident.
But it wasn't until the late 1980s that biologists realized that natural selection could be observed in action as well. The key is the fact that different traits result in a different rate of survival as well as reproduction, and may be passed on from one generation to the next.
In the past, if a certain allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it might become more common than any other allele. Over time, this would 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 see evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples from each population are taken on a regular basis, and over 500.000 generations have been observed.
Lenski's research has revealed that mutations can drastically alter the efficiency with which a population reproduces--and so the rate at which it alters. It also proves that evolution is slow-moving, a fact that some find hard to accept.
Another example of microevolution is how mosquito genes that confer resistance to pesticides appear more frequently in areas in which insecticides are utilized. Pesticides create a selective pressure which favors those with resistant genotypes.
The rapidity of evolution has led to an increasing recognition of its importance especially in a planet shaped largely by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding evolution can aid you in making better decisions about the future of the planet and its inhabitants.