The Academy's Evolution Site
Biological evolution is one of the most fundamental concepts in biology. The Academies have been for a long time involved in helping people who are interested in science comprehend the theory of evolution and how it permeates every area of scientific inquiry.
This site provides teachers, students and general readers with a range of learning resources about evolution. It includes key video clip 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 life. It appears in many cultures and spiritual beliefs as symbolizing unity and love. It has many practical applications as well, including providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
The first attempts at depicting the world of biology focused on separating species into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, which relied on the sampling of various parts of living organisms or short fragments of their DNA, greatly increased the variety of organisms that could be represented in the tree of life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.
Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular methods like the small-subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of diversity to be discovered. This is particularly true for microorganisms, which can be difficult to cultivate and are often only found in a single sample5. A recent analysis of all known genomes has created a rough draft of the Tree of Life, including many archaea and bacteria 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 region and determine if specific habitats require special protection. The information is useful in a variety of ways, including finding new drugs, battling diseases and improving crops. This information is also extremely valuable in conservation efforts. It can aid biologists in identifying areas that are likely to be home to cryptic species, which could perform important metabolic functions, and could be susceptible to changes caused by humans. While conservation funds are essential, the best method to preserve the world's biodiversity is to equip more people in developing nations with the information they require to take action locally and encourage conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the relationships between various groups of organisms. Utilizing molecular data as well as morphological similarities and distinctions, 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 is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that have evolved from common ancestors. These shared traits can be either analogous or homologous. Homologous traits are the same in their evolutionary journey. Analogous traits could appear like they are but they don't have the same origins. Scientists combine similar traits into a grouping called a the clade. For instance, all of the organisms that make up a clade have the characteristic of having amniotic eggs and evolved from a common ancestor that had eggs. A phylogenetic tree can be constructed by connecting clades to determine the organisms that are most closely related to each other.
Scientists use DNA or RNA molecular information to create a phylogenetic chart which is more precise and precise. This information is more precise and gives evidence of the evolution history of an organism. Researchers can use Molecular Data to estimate the evolutionary age of living organisms and discover how many organisms have a common ancestor.
The phylogenetic relationships of a species can be affected by a variety of factors, including phenotypicplasticity. This is a type of behavior that changes due to particular environmental conditions. 에볼루션 게이밍 can make a trait appear more similar to a species than to another and obscure the phylogenetic signals. However, this issue can be solved through the use of methods such as cladistics that incorporate a combination of homologous and analogous features into the tree.
In addition, phylogenetics helps determine the duration and speed at which speciation takes place. Recommended Website can assist conservation biologists decide the species they should safeguard from the threat of extinction. It is ultimately the preservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme of evolution is that organisms acquire different features over time due to their interactions with their environment. Several theories 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 envisioned an organism developing slowly according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that can be passed onto offspring.
In the 1930s and 1940s, ideas from a variety of fields -- including genetics, natural selection, and particulate inheritance -- came together to form the modern evolutionary theory synthesis, which defines how evolution occurs through the variations of genes within a population and how these variants change in time due to natural selection. This model, known as genetic drift mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically described.
Recent advances in the field of evolutionary developmental biology have shown the ways in which variation can be introduced to a species via mutations, genetic drift, reshuffling genes during sexual reproduction and the movement between populations. These processes, in conjunction with other ones like the directional selection process and the erosion of genes (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time as well as changes in phenotype (the expression of genotypes in individuals).
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 example, showed that teaching about the evidence supporting evolution helped students accept the concept of evolution in a college biology class. For more information on how to teach about evolution, please look up The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species and observing living organisms. Evolution isn't a flims moment; it is an ongoing process that continues to be observed today. Viruses reinvent themselves to avoid new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior as a result of a changing world. The changes that occur are often apparent.
However, it wasn't until late 1980s that biologists realized that natural selection can be observed in action as well. The key is the fact that different traits can confer an individual rate of survival and reproduction, and can be passed down from generation to generation.
In the past, if an allele - the genetic sequence that determines colour was found in a group of organisms that interbred, it might become more common than any other allele. In time, this could mean that the number of moths sporting 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.
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 of each population are taken every day and more than 500.000 generations have passed.
Lenski's research has revealed that mutations can alter the rate of change and the rate at which a population reproduces. It also proves that evolution takes time, a fact that some are unable to accept.
Microevolution can be observed in the fact that mosquito genes for resistance to pesticides are more prevalent in areas where insecticides have been used. This is because the use of pesticides creates a pressure that favors people who have resistant genotypes.
The rapid pace at which evolution takes place has led to an increasing awareness of its significance in a world that is shaped by human activities, including climate change, pollution, and the loss of habitats which prevent many species from adapting. Understanding evolution can help us make smarter choices about the future of our planet and the lives of its inhabitants.