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 theory of evolution and how it permeates every area of scientific inquiry.
This site provides a wide range of tools for teachers, students and general readers of 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 of the interconnectedness of all life. It is a symbol of love and unity across many cultures. It has many practical applications in addition to providing a framework to understand the history of species and how they respond to changing environmental conditions.
Early attempts to describe the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods are based on the collection of various parts of organisms or DNA fragments, have greatly increased the diversity of a tree of Life2. These trees are largely composed by eukaryotes, and bacteria are largely underrepresented3,4.
In avoiding the necessity of direct experimentation and observation genetic techniques have enabled us to represent the Tree of Life in a more precise manner. We can create trees by using molecular methods, such as the small-subunit ribosomal gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true of microorganisms, which are difficult to cultivate and are typically only found in a single specimen5. A recent analysis of all known genomes has produced a rough draft version of the Tree of Life, including numerous archaea and bacteria that have not been isolated, and whose diversity is poorly understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine whether specific habitats require protection. This information can be utilized in a variety of ways, including identifying new drugs, combating diseases and improving the quality of crops. The information is also beneficial in conservation efforts. It can help biologists identify areas most likely to have species that are cryptic, which could perform important metabolic functions and be vulnerable to changes caused by humans. While funds to protect biodiversity are important, the most effective method to protect the biodiversity of the world is to equip the people of developing nations with the necessary knowledge to act locally and promote conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, shows the connections between different groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic groups based on molecular data and morphological differences or similarities. The phylogeny of a tree plays an important role in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from an ancestor that shared traits. These shared traits can be homologous, or analogous. Homologous characteristics are identical in their evolutionary paths. Analogous traits may look like they are but they don't share the same origins. Scientists organize similar traits into a grouping referred to as a clade. For instance, all the organisms in a clade have the characteristic of having amniotic eggs and evolved from a common ancestor that had eggs. 에볼루션 무료 바카라 are then linked to create a phylogenetic tree to determine which organisms have the closest connection to each other.
For a more precise and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to determine the connections between organisms. This data is more precise than morphological data and provides evidence of the evolutionary background of an organism or group. Researchers can use Molecular Data to estimate the age of evolution of organisms and identify how many organisms share an ancestor common to all.
Phylogenetic relationships can be affected by a number of factors such as phenotypicplasticity. This is a type behaviour that can change due to unique environmental conditions. This can cause a trait to appear more like a species another, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which incorporates a combination of homologous and analogous traits in the tree.
Additionally, phylogenetics can aid in predicting the length and speed of speciation. This information can help conservation biologists decide which species they should protect from extinction. In the end, it is the conservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The fundamental concept of evolution is that organisms acquire distinct characteristics over time as a result of their interactions with their environment. Many theories of evolution have been proposed by a 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 and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that could be passed on to offspring.
In the 1930s & 1940s, theories from various fields, such as genetics, natural selection, and particulate inheritance, came together to form a contemporary evolutionary theory. This defines how evolution occurs by the variation in genes within the population, and how these variations change with time due to natural selection. This model, which encompasses genetic drift, mutations as well as gene flow and sexual selection can be mathematically described mathematically.
Recent developments in evolutionary developmental biology have revealed how variation can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction and the movement between populations. These processes, along with others such as directionally-selected selection and erosion of genes (changes in frequency of genotypes over time) can lead to evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in an individual).
Incorporating evolutionary thinking into all aspects of biology education can increase student understanding of the concepts of phylogeny as well as evolution. A recent study conducted by Grunspan and colleagues, for example revealed that teaching students about the evidence that supports evolution increased students' understanding of evolution in a college biology course. To find out 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, studying fossils, comparing species and studying living organisms. Evolution isn't a flims moment; it is a process that continues today. Bacteria mutate and resist antibiotics, viruses evolve and are able to evade new medications and animals change their behavior to a changing planet. The resulting changes are often easy to see.
However, it wasn't until late-1980s that biologists realized that natural selection could be seen in action, as well. The key to this is that different traits confer the ability to survive at different rates and reproduction, and they can be passed on from one generation to another.
In the past when one particular allele - the genetic sequence that controls coloration - was present in a group of interbreeding species, it could quickly become more common than other alleles. Over time, that would mean that the number of black moths in 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 the species, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from one strain. Samples of each population have been taken regularly and more than 500.000 generations of E.coli have passed.
Lenski's research has revealed that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows that evolution takes time, something that is hard for some to accept.
Another example of microevolution is how mosquito genes that confer resistance to pesticides are more prevalent in areas in which insecticides are utilized. This is because the use of pesticides creates a pressure that favors people with resistant genotypes.
The rapid pace of evolution taking place has led to an increasing appreciation of its importance in a world shaped by human activities, including climate change, pollution, and the loss of habitats which prevent many species from adapting. Understanding evolution can help you make better decisions regarding the future of the planet and its inhabitants.