The Academy's Evolution Site
The concept of biological evolution is among the most fundamental concepts in biology. The Academies have been active for a long time in helping those interested in science understand the theory of evolution and how it affects all areas of scientific exploration.
This site provides a wide range of tools for teachers, students and general readers of evolution. It contains important video clips from NOVA and WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is used in many cultures and spiritual beliefs as an emblem of unity and love. It has many practical applications as well, such as providing a framework for understanding the history of species, and how they react to changing environmental conditions.
Early attempts to represent the world of biology were founded on categorizing organisms on their metabolic and physical characteristics. These methods, based on sampling of different parts of living organisms or on small fragments of their DNA significantly expanded the diversity that could be included in a tree of life2. However these trees are mainly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.
By avoiding the necessity for direct observation and experimentation genetic techniques have made it possible to represent the Tree of Life in a much more accurate way. Trees can be constructed using molecular techniques like the small-subunit ribosomal gene.
The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are typically only present in a single sample5. A recent study of all known genomes has produced a rough draft version of the Tree of Life, including many bacteria and archaea that are not isolated and their diversity is not fully understood6.
This expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if specific habitats need special protection. This information can be used in many ways, including identifying new drugs, combating diseases and enhancing crops. This information is also useful for conservation efforts. It can help biologists identify the areas most likely to contain cryptic species that could have important metabolic functions that could be vulnerable to anthropogenic change. While conservation funds are important, the most effective method to preserve the world's biodiversity is to equip the people of developing nations with the necessary knowledge to take action locally and encourage conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, shows the relationships between various groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolution of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits could be analogous or homologous. Homologous traits share their evolutionary origins while analogous traits appear similar but do not have the same origins. Scientists group similar traits into a grouping referred to as a the clade. For instance, all the species in a clade share the trait of having amniotic eggs. They evolved from a common ancestor that had eggs. A phylogenetic tree is built by connecting the clades to identify the species which are the closest to each other.
Scientists utilize DNA or RNA molecular data to construct a phylogenetic graph that is more accurate and detailed. This information is more precise and provides evidence of the evolution history of an organism. Researchers can utilize Molecular Data to calculate the evolutionary age of living organisms and discover the number of organisms that have an ancestor common to all.
Phylogenetic relationships can be affected by a number of factors, including phenotypicplasticity. This is a type behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to a species than to another and obscure the phylogenetic signals. However, this problem can be reduced by the use of techniques such as cladistics which incorporate a combination of homologous and analogous features into the tree.
Furthermore, phylogenetics may help predict the length and speed of speciation. This information can assist conservation biologists make decisions about which species they should protect from extinction. In the end, it is the conservation of phylogenetic variety that will lead to an ecosystem that is balanced and complete.
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 wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that can be passed on to the offspring.
In the 1930s & 1940s, ideas from different fields, including genetics, natural selection and particulate inheritance, merged to form a contemporary evolutionary theory. This explains how evolution is triggered by the variation of genes in the population, and how these variants change with time due to natural selection. 에볼루션바카라사이트 , which incorporates genetic drift, mutations, gene flow and sexual selection can be mathematically described mathematically.
Recent advances in the field of evolutionary developmental biology have revealed how variation can be introduced to a species via mutations, genetic drift, reshuffling genes during sexual reproduction, and even migration between populations. These processes, along with other ones like directional selection and 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 the change in phenotype as time passes (the expression of the genotype in the individual).
Incorporating evolutionary thinking into all aspects of biology education can improve students' understanding of phylogeny and 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 in a college-level course in biology. To learn more about how to teach about evolution, look up The Evolutionary Potential of 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, studying fossils, comparing species, and observing living organisms. Evolution is not a distant moment; it is an ongoing process. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior as a result of a changing environment. The changes that result are often visible.
It wasn't until late 1980s that biologists began realize that natural selection was also in action. The main reason is that different traits confer the ability to survive at different rates and reproduction, and can be passed down 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 could be more common than other allele. As time passes, that could mean that the number of black moths within 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 an organism, like bacteria, has a high 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 over fifty thousand generations have passed.
Lenski's research has revealed that mutations can alter the rate at which change occurs and the efficiency of a population's reproduction. It also shows that evolution is slow-moving, a fact that many find hard to accept.
Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations that have used insecticides. Pesticides create an enticement that favors those with resistant genotypes.
The rapid pace at which evolution can take place has led to an increasing appreciation of its importance in a world shaped by human activity, including climate changes, pollution and the loss of habitats that hinder the species from adapting. Understanding evolution will help us make better choices about the future of our planet, as well as the lives of its inhabitants.