The Academy's Evolution Site
The concept of biological evolution is a fundamental concept 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 students, teachers and general readers with a range of educational resources 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 represents the interconnectedness of all life. It is a symbol of love and unity in many cultures. It also has important practical applications, such as providing a framework to understand the evolution of species and how they react to changes in environmental conditions.
The first attempts to depict the world of biology were built on categorizing organisms based on their physical and metabolic characteristics. These methods, which relied on the sampling of different parts of living organisms or sequences of short fragments of their DNA, greatly increased the variety of organisms that could be included in a tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have greatly broadened our ability to depict 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 such as the small subunit ribosomal gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate and are usually present in a single sample5. A recent analysis of all genomes resulted in a rough draft of the Tree of Life. This includes a wide range of archaea, bacteria and other organisms that haven't yet been isolated or their diversity is not thoroughly understood6.
The expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if certain habitats require special protection. The information is useful in many ways, including finding new drugs, fighting diseases and enhancing crops. This information is also extremely beneficial for conservation efforts. It helps biologists discover areas most likely to be home to species that are cryptic, which could have important metabolic functions and be vulnerable to changes caused by humans. While 에볼루션 to protect biodiversity are essential however, the most effective method to ensure the preservation of biodiversity around the world is for more people in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, illustrates the relationships between different groups of organisms. Using molecular data, morphological similarities and differences 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 essential in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from a common ancestor. These shared traits can be either homologous or analogous. Homologous traits share their underlying evolutionary path and analogous traits appear similar but do not have the same ancestors. Scientists put similar traits into a grouping referred to as a the clade. For instance, all of the species in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor which had eggs. The clades are then linked to create a phylogenetic tree to determine which organisms have the closest relationship to.
To create a more thorough and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to determine the connections 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 identify the number of organisms who share a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic flexibility, a kind of behavior that changes in response to specific environmental conditions. This can make a trait appear more similar to one species than to another which can obscure the phylogenetic signal. This issue can be cured by using cladistics, which incorporates an amalgamation of homologous and analogous traits in the tree.
Furthermore, phylogenetics may help predict the time and pace of speciation. This information can aid conservation biologists to make decisions about the species they should safeguard from extinction. In the end, it's the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms acquire distinct characteristics over time based on 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 could evolve according to its individual needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of certain traits can result in changes that are passed on to the
In the 1930s and 1940s, theories from a variety of fields -- including genetics, natural selection and particulate inheritance--came together to form the current evolutionary theory that explains how evolution is triggered by the variation of genes within a population and how those variants change over time as a result of natural selection. This model, which incorporates genetic drift, mutations as well as gene flow and sexual selection is mathematically described mathematically.
Recent discoveries in the field of evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species via genetic drift, mutations or reshuffling of genes in sexual reproduction and migration between populations. These processes, as well as others 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 also by changes in phenotype over time (the expression of that genotype within the individual).
Incorporating evolutionary thinking into all aspects of biology education can increase student understanding of the concepts of phylogeny as well as evolution. In a study by Grunspan et al. It was demonstrated that teaching students about the evidence for evolution increased their acceptance of evolution during an undergraduate biology course. To find out more about how to teach about evolution, read The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily 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 study living organisms. However, evolution isn't something that occurred in the past. It's an ongoing process, that is taking place in the present. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior in the wake of a changing environment. The changes that occur are often visible.
It wasn't until late 1980s when biologists began to realize that natural selection was also in play. The main reason is that different traits confer a different rate of survival and reproduction, and they can be passed down from one generation to another.
In the past, if one particular allele - the genetic sequence that determines coloration--appeared in a population of interbreeding species, it could rapidly become more common than other alleles. In time, this could mean that the number of black moths in a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to track evolution when an organism, like 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 50,000 generations have now been observed.
Lenski's research has demonstrated that mutations can alter the rate of change and the efficiency of a population's reproduction. It also shows that evolution takes time, which is hard for some to accept.
Microevolution is also evident in the fact that mosquito genes that confer resistance to pesticides are more common in populations where insecticides have been used. This is due to pesticides causing an enticement that favors those with resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance, especially in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding the evolution process can help us make better decisions regarding the future of our planet, and the life of its inhabitants.