The Academy's Evolution Site
Biology is a key concept in biology. The Academies have long been involved in helping people who are interested in science understand the concept of evolution and how it affects every area of scientific inquiry.
This site provides students, teachers and general readers with a variety of educational resources on evolution. It has the most important video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and unity across many cultures. It also has many practical applications, like providing a framework to understand the evolution of species and how they react to changing environmental conditions.
Early attempts to represent the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods depend on the sampling of different parts of organisms or DNA fragments, have significantly increased the diversity of a tree of Life2. These trees are largely composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods allow us to construct trees using sequenced markers like the small subunit ribosomal RNA gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially true of microorganisms that are difficult to cultivate and are typically only present in a single specimen5. A recent analysis of all genomes has produced a rough draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that haven't yet been isolated, or their diversity is not thoroughly understood6.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine whether specific habitats require special protection. This information can be utilized in a range of ways, from identifying the most effective treatments to fight disease to enhancing the quality of crops. Going In this article is also useful to conservation efforts. It can aid biologists in identifying areas most likely to have cryptic species, which may have important metabolic functions and are susceptible to human-induced change. While funding to protect biodiversity are essential, the best method to protect the world's biodiversity is to equip more people in developing countries with the necessary knowledge to act locally and promote conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, shows the relationships between various groups of organisms. Utilizing molecular data as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism), scientists can build an phylogenetic tree that demonstrates the evolution of taxonomic categories. Phylogeny is crucial in understanding biodiversity, evolution 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 can be homologous, or analogous. Homologous traits are similar in their evolutionary paths. Analogous traits might appear like they are however they do not share the same origins. Scientists put similar traits into a grouping called a Clade. All members of a clade have a common trait, such as amniotic egg production. They all came from an ancestor who had these eggs. The clades are then connected to form a phylogenetic branch that can identify organisms that have the closest relationship to.
For a more precise and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to establish the connections between organisms. 에볼루션 슬롯게임 is more precise than morphological data and provides evidence of the evolutionary history of an organism or group. Molecular data allows researchers to determine the number of organisms that have the same ancestor and estimate their evolutionary age.
The phylogenetic relationship can be affected by a number of factors that include the phenotypic plasticity. This is a type behavior that alters as a result of particular environmental conditions. This can cause a characteristic to appear more similar to a species than another, obscuring the phylogenetic signals. However, this issue can be solved through the use of techniques such as cladistics that incorporate a combination of homologous and analogous features into the tree.
Additionally, phylogenetics can aid in predicting the duration and rate of speciation. This information can aid conservation biologists in deciding which species to safeguard from disappearance. In the end, it's the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme in evolution is that organisms alter over time because of their interactions with their environment. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would evolve according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of certain traits can result in changes that are passed on to the next generation.
In the 1930s and 1940s, ideas from a variety of fields -- including natural selection, genetics, and particulate inheritance--came together to form the modern synthesis of evolutionary theory that explains how evolution is triggered by the variation of genes within a population and how those variations change over time as a result of natural selection. This model, which incorporates mutations, genetic drift in gene flow, and sexual selection can be mathematically described.
Recent developments in the field of evolutionary developmental biology have shown that variation can be introduced into a species via mutation, genetic drift, and reshuffling of genes during sexual reproduction, as well as through migration between populations. These processes, in conjunction with others such as directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in individuals).
Students can better understand phylogeny by incorporating evolutionary thinking in all areas of biology. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution increased students' acceptance of evolution in a college biology course. 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 the Concept of Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through looking back--analyzing fossils, comparing species, and studying living organisms. Evolution is not a distant moment; it is an ongoing process. Bacteria transform and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals alter their behavior in response to the changing climate. The changes that result are often apparent.
It wasn't until late 1980s when biologists began to realize that natural selection was at work. The key is the fact that different traits result in a different rate of survival and reproduction, and can be passed on from one generation to another.
In the past, if one allele - the genetic sequence that determines colour appeared in a population of organisms that interbred, it could become more common than other allele. Over time, this would mean that the number of moths with black pigmentation in a population may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to track evolutionary change when a species, such as bacteria, has a rapid generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each are taken every day and over 500.000 generations have been observed.
Lenski's research has shown that mutations can drastically alter the rate at which a population reproduces--and so, the rate at which it alters. It also demonstrates that evolution is slow-moving, a fact that some people find hard 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. Pesticides create a selective pressure which favors individuals who have resistant genotypes.
The rapidity of evolution has led to a growing awareness of its significance especially in a planet shaped largely by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding the evolution process can help us make smarter decisions regarding the future of our planet and the lives of its inhabitants.