The Academy's Evolution Site
Biological evolution is one of the most central concepts in biology. The Academies are involved in helping those who are interested in the sciences learn about the theory of evolution and how it is incorporated throughout all fields of scientific research.
This site provides teachers, students and general readers with a variety of learning resources on evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is an emblem of love and unity in many cultures. It has numerous practical applications as well, including providing a framework to understand the history of species, and how they respond to changes in environmental conditions.
에볼루션카지노사이트 to depicting the biological world focused on separating organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods depend on the sampling of different parts of organisms or short 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.
Genetic techniques have significantly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques allow us to build trees using sequenced markers such as the small subunit ribosomal gene.
Despite the rapid growth of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially relevant to microorganisms that are difficult to cultivate and which are usually only found in a single specimen5. Recent analysis of all genomes has produced an unfinished draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that have not yet been isolated, or whose diversity has not been thoroughly understood6.
This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if particular habitats require special protection. This information can be utilized in a variety of ways, including identifying new drugs, combating diseases and enhancing crops. The information is also incredibly useful for conservation efforts. It helps biologists discover areas that are most likely to be home to cryptic species, which could perform important metabolic functions, and could be susceptible to the effects of human activity. While funds to protect biodiversity are crucial, ultimately the best way to ensure the preservation of biodiversity around the world is for more people living 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, shows the connections between various groups of organisms. Scientists can construct a phylogenetic chart that shows the evolutionary relationship of taxonomic groups using 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 ) is a method of identifying the relationships between organisms that share similar traits that have evolved from common ancestors. These shared traits are either analogous or homologous. Homologous traits are similar in their underlying evolutionary path and analogous traits appear similar, but do not share the identical origins. Scientists organize similar traits into a grouping referred to as a clade. For instance, all of the species in a clade share the trait of having amniotic eggs. click through the following post evolved from a common ancestor who had eggs. A phylogenetic tree is constructed by connecting the clades to identify the species that are most closely related to one another.
For a more detailed and accurate phylogenetic tree, scientists use molecular data from DNA or RNA to establish the relationships between organisms. This information is more precise and provides evidence of the evolution history of an organism. Molecular data allows researchers to identify the number of species that share a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships between organisms can be influenced by several factors, including phenotypic plasticity a type of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than another, obscuring the phylogenetic signal. However, this issue can be solved through the use of techniques such as cladistics which include a mix of homologous and analogous features into the tree.
Additionally, phylogenetics aids determine the duration and rate of speciation. This information can assist conservation biologists decide which species they should protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms acquire various characteristics over time as a result of their interactions with their surroundings. Many theories of 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 requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that can be passed on to the offspring.
In the 1930s & 1940s, concepts from various areas, 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 variations change with time due to natural selection. This model, called genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that variations can be introduced into a species by mutation, genetic drift, and reshuffling genes during sexual reproduction, and also through the movement of populations. These processes, as well as others such as directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time and changes in the phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology course. For more information on how to teach about evolution, see The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution through looking back in the past, studying fossils, and comparing species. They also observe living organisms. Evolution is not a distant moment; it is an ongoing process. Bacteria evolve and resist antibiotics, viruses evolve and elude new medications and animals change their behavior in response to the changing environment. The resulting changes are often visible.
It wasn't until the late 1980s that biologists began to realize that natural selection was in action. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) 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 might become more common than any other allele. Over time, that would 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 see 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. Coli that descended from a single strain. samples from each population are taken regularly and more than 500.000 generations have passed.
Lenski's research has revealed that a mutation can profoundly alter the efficiency with which a population reproduces--and so the rate at which it alters. It also proves that evolution takes time, a fact that many find hard to accept.
Another example of microevolution is the way mosquito genes that are resistant to pesticides appear more frequently in populations where insecticides are employed. This is due to the fact that the use of pesticides creates a pressure that favors those who have resistant genotypes.
The speed at which evolution takes place has led to an increasing recognition of its importance in a world that is shaped by human activities, including climate change, pollution, and the loss of habitats that prevent many species from adapting. Understanding evolution can help us make better decisions about the future of our planet and the lives of its inhabitants.