The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies are involved in helping those who are interested in science to understand evolution theory and how it is permeated throughout all fields of scientific research.
This site provides teachers, students and general readers with a wide range of educational resources on evolution. It has important video clips from NOVA and the 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 appears in many religions and cultures as a symbol of unity and love. It also has important practical uses, like providing a framework to understand the history of species and how they respond to changing environmental conditions.
에볼루션 슬롯 at depicting the biological world focused on categorizing species into distinct categories that were distinguished by physical and metabolic characteristics1. These methods depend on the collection of various parts of organisms or fragments of DNA have significantly increased the diversity of a Tree of Life2. The trees are mostly composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to construct trees using sequenced markers such as the small subunit of ribosomal RNA gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. This is particularly true for microorganisms that are difficult to cultivate and are typically only represented in a single specimen5. A recent study of all genomes that are known has created a rough draft of the Tree of Life, including many archaea and bacteria that have not been isolated and which are not well understood.
The expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if certain habitats need special protection. This information can be utilized in a range of ways, from identifying new remedies to fight diseases to enhancing crops. It is also useful in conservation efforts. It can help biologists identify areas that are likely to have species that are cryptic, which could perform important metabolic functions, and could be susceptible to changes caused by humans. While funding to protect biodiversity are essential, the best method to preserve the biodiversity of the world is to equip more people in developing countries with the information they require to act locally and promote conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the relationships between groups of organisms. Scientists can create a phylogenetic chart that shows the evolutionary relationships between taxonomic groups based on molecular data and morphological differences or similarities. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar traits and evolved from an ancestor that shared traits. These shared traits are either analogous or homologous. Homologous traits are identical in their evolutionary roots while analogous traits appear like they do, but don't have the identical origins. Scientists combine similar traits into a grouping called a clade. All members of a clade have a common characteristic, for example, amniotic egg production. They all derived from an ancestor with these eggs. The clades are then linked to form a phylogenetic branch to determine which organisms have the closest relationship to.
To create a more thorough and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the connections between organisms. This information is more precise and gives evidence of the evolution history of an organism. Researchers can use Molecular Data to determine the age of evolution of living organisms and discover how many species share an ancestor common to all.
The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic flexibility, an aspect of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar to one species than to the other, obscuring the phylogenetic signals. This issue can be cured by using cladistics, which incorporates the combination of analogous and homologous features in the tree.
Additionally, phylogenetics can help determine the duration and speed at which speciation takes place. This information can aid conservation biologists to decide which species they should protect from extinction. In the end, it's the conservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms change over time as a result of their interactions with their environment. A variety of theories about evolution 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 according to its needs, 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 could be passed on to offspring.
In the 1930s & 1940s, concepts from various fields, including natural selection, genetics & particulate inheritance, came together to form a modern evolutionary theory. This defines how evolution is triggered by the variations in genes within the population and how these variants change with time due to natural selection. This model, known as genetic drift mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and can be mathematically explained.
Recent discoveries in evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species by mutations, genetic drift or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, in conjunction with other ones like directional selection and gene erosion (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in individuals).
Students can better understand phylogeny by incorporating evolutionary thinking in all areas of biology. In a 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 find out more about how to teach about evolution, please read The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through studying fossils, comparing species and observing living organisms. But evolution isn't a thing that happened in the past. It's an ongoing process that is taking place today. Bacteria transform and resist antibiotics, viruses evolve and elude new medications and animals alter their behavior to the changing climate. The results are usually evident.
It wasn't until the 1980s that biologists began realize that natural selection was also in action. The reason is that different characteristics result in different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.
In the past, if one allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could become more common than any other allele. In time, 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 particular species has a fast generation turnover, as with bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. Samples of each population were taken regularly, and more than 50,000 generations of E.coli have passed.
Lenski's work has demonstrated that a mutation can dramatically 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 many find difficult to accept.
Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more common in populations that have used insecticides. This is because pesticides cause an exclusive pressure that favors individuals who have resistant genotypes.
The rapidity of evolution has led to a growing awareness of its significance especially in a planet which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution will help us make better decisions regarding the future of our planet and the life of its inhabitants.