The Academy's Evolution Site
Biology is one of the most fundamental concepts in biology. The Academies are involved in helping those who are interested in science understand evolution theory and how it is incorporated across all areas of scientific research.
This site provides teachers, students and general readers with a range of learning resources on evolution. It has key video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is an emblem of love and unity across many cultures. It can be used in many practical ways in addition to providing a framework to understand the evolution of species and how they respond to changing environmental conditions.
Early attempts to describe the biological world were based on categorizing organisms based on their physical and metabolic characteristics. These methods are based on the collection of various parts of organisms or short DNA fragments, have significantly increased the diversity of a Tree of Life2. However the trees are mostly made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular methods allow us to build trees by using sequenced markers like the small subunit of ribosomal RNA gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are usually present in a single sample5. A recent analysis of all known genomes has produced a rough draft version 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 region and determine if particular habitats need special protection. The information is useful in many ways, including finding new drugs, fighting diseases and enhancing crops. The information is also incredibly useful for conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with potentially important metabolic functions that may be at risk of anthropogenic changes. Although funds to protect biodiversity are crucial but the most effective 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, reveals the connections between groups of organisms. By using molecular information 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 relationships between taxonomic categories. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous traits are similar in their underlying evolutionary path, while analogous traits look like they do, but don't have the same origins. Scientists combine similar traits into a grouping known as a Clade. For instance, all of the organisms in a clade share the trait of having amniotic eggs. They evolved from a common ancestor that had eggs. The clades are then linked to form a phylogenetic branch to determine the organisms with the closest connection to each other.
Scientists utilize molecular DNA or RNA data to construct a phylogenetic graph which is more precise and detailed. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to estimate the evolutionary age of living organisms and discover how many species have an ancestor common to all.
Phylogenetic relationships can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is 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, obscuring the phylogenetic signals. This problem can be addressed by using cladistics, which incorporates an amalgamation of analogous and homologous features in the tree.
Additionally, phylogenetics aids determine the duration and speed at which speciation takes place. This information can aid conservation biologists in making decisions about which species to save from extinction. In the end, it is the conservation of phylogenetic variety which will create an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme of evolution is that organisms acquire different features over time as a result of their interactions with their surroundings. mouse click the up coming internet site of evolutionary change have been developed by a wide variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits cause changes that can be passed on to the offspring.
In the 1930s and 1940s, theories from various fields, such as genetics, natural selection and particulate inheritance, were brought together to form a contemporary evolutionary theory. This defines how evolution occurs by the variation of genes in the population and how these variants change over time as a result of natural selection. This model, which includes genetic drift, mutations, gene flow and sexual selection can be mathematically described mathematically.
Recent advances in the field of evolutionary developmental biology have shown how variation can be introduced to a species by genetic drift, mutations or reshuffling of genes in sexual reproduction, and even migration between 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 the change in phenotype over time (the expression of that genotype within the individual).
Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny as well as evolution. In a recent study conducted by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. To find out more about how to teach about evolution, see The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution by looking in the past, analyzing fossils and comparing species. They also study living organisms. But evolution isn't a thing that happened in the past, it's an ongoing process that is happening right now. Bacteria transform and resist antibiotics, viruses reinvent themselves and elude new medications and animals alter their behavior to the changing environment. The changes that occur are often evident.
It wasn't until late-1980s that biologists realized that natural selection can be observed in action as well. The key is that different traits have different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.
In the past, if an allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could become more common than any other allele. As time passes, this could mean that the number of moths sporting black pigmentation may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
The ability to observe evolutionary change is easier when a species has a rapid generation turnover like bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples of each are taken regularly, and over fifty thousand generations have been observed.
Lenski's research has revealed that a mutation can profoundly alter the speed at 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 find difficult to accept.
Microevolution can be observed in the fact that mosquito genes for resistance to pesticides are more common in populations where insecticides have been used. This is due to pesticides causing an exclusive pressure that favors those with resistant genotypes.
The rapid pace at which evolution takes place has led to a growing recognition of its importance in a world that is shaped by human activities, including climate changes, pollution and the loss of habitats which prevent many species from adapting. Understanding evolution can help us make better choices about the future of our planet as well as the life of its inhabitants.