The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies are involved in helping those interested in the sciences understand evolution theory and how it can be applied across all areas of scientific research.
This site provides students, teachers and general readers with a variety of educational resources on evolution. It contains the most important video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It appears in many spiritual traditions and cultures as symbolizing unity and love. It also has practical applications, like providing a framework for understanding the history of species and how they react to changing environmental conditions.
The earliest attempts to depict the biological world focused on separating species into distinct categories that were distinguished by physical and metabolic characteristics1. These methods, based on sampling of different parts of living organisms, or sequences of short fragments of their DNA, significantly increased the variety that could be included in the tree of life2. The trees are mostly 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 methods allow us to build trees using sequenced markers, such as the small subunit of ribosomal RNA gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a large amount of biodiversity remains to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate, and which are usually only found in a single specimen5. A recent analysis of all genomes has produced an unfinished draft of a Tree of Life. This includes a variety of archaea, bacteria, and other organisms that haven't yet been isolated or the diversity of which 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 need special protection. This information can be utilized in many ways, including finding new drugs, battling diseases and improving the quality of crops. This information is also extremely useful in conservation efforts. It helps biologists discover areas that are likely to be home to cryptic species, which could have vital metabolic functions, and could be susceptible to changes caused by humans. Although funds to protect biodiversity are crucial however, the most effective method to protect the world's biodiversity is for more people in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the relationships between various groups of organisms. Utilizing 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 relationship between taxonomic categories. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar characteristics and have evolved from a common ancestor. These shared traits can be either homologous or analogous. Homologous characteristics are identical in their evolutionary path. Analogous traits might appear similar, but they do not have the same ancestry. Scientists arrange similar traits into a grouping known as a clade. For instance, all the organisms that make up a clade share the trait of having amniotic eggs and evolved from a common ancestor who had these eggs. A phylogenetic tree can be constructed by connecting the clades to identify the species who are the closest to each other.
Scientists make use of DNA or RNA molecular information to build a phylogenetic chart that is more accurate and precise. This information is more precise and provides evidence of the evolution history of an organism. The use of molecular data lets researchers identify the number of organisms who share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships of a species can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is a type of behavior that alters in response to particular environmental conditions. This can cause a trait to appear more similar in one species than other species, which can obscure the phylogenetic signal. However, this issue can be reduced by the use of methods like cladistics, which incorporate a combination of homologous and analogous features into the tree.
In addition, phylogenetics can help predict the length and speed of speciation. This information can assist conservation biologists decide the species they should safeguard from the threat of extinction. It is ultimately the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms alter over time because of their interactions with their environment. Many theories of evolution have been proposed by a variety of scientists including 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 developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that could be passed on to the offspring.
In the 1930s and 1940s, ideas from different fields, including natural selection, genetics & particulate inheritance, came together to form a contemporary evolutionary theory. This defines how evolution is triggered by the variation of genes in the population, and how these variations change over time as a result of natural selection. This model, known as genetic drift or mutation, gene flow and sexual selection, is the foundation of modern evolutionary biology and can be mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that variation can be introduced into a species by mutation, genetic drift, and reshuffling genes during sexual reproduction, and also by migration between populations. 에볼루션 카지노 , as well as others such as directional selection or genetic erosion (changes in the frequency of a genotype over time) can lead to evolution that is defined as change in the genome of the species over time and also by changes in phenotype as time passes (the expression of the genotype in an individual).
Students can better understand the concept of phylogeny by using evolutionary thinking in all areas of biology. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence for evolution increased students' acceptance of evolution in a college biology course. For more details on how to teach evolution read The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution through looking back in 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 happening right now. Bacteria mutate and resist antibiotics, viruses evolve and escape new drugs and animals change their behavior in response to the changing environment. The changes that result are often visible.
It wasn't until late 1980s that biologists began to realize that natural selection was also in play. The key to this is that different traits confer a different rate of survival and reproduction, and can be passed down from generation to generation.
In the past, if one particular allele, the genetic sequence that controls coloration - was present in a population of interbreeding organisms, it might quickly become more common than other alleles. In time, this could mean that the number of moths with black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is easier when a particular species has a fast generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. Samples of each population were taken regularly, and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the rate at which a population reproduces. It also demonstrates that evolution takes time--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 prevalent in populations where insecticides have been used. This is because the use of pesticides causes a selective pressure that favors those with resistant genotypes.
The rapidity of evolution has led to a growing appreciation of its importance, especially in a world which is largely shaped by human activities. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding the evolution process will help you make better decisions about the future of the planet and its inhabitants.