This Is A Evolution Site Success Story You'll Never Be Able To
The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have been for a long time involved in helping those interested in science understand the theory of evolution and how it affects all areas of scientific exploration.
This site provides teachers, students and general readers with a variety of educational resources on evolution. It contains key video clips 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 seen in a variety of religions and cultures as an emblem of 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 first attempts at depicting the world of biology focused on categorizing organisms into distinct categories that were identified by their physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms or sequences of short DNA fragments, greatly increased the variety of organisms that could be included in a tree of life2. These trees are mostly populated of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. We can construct trees using molecular methods like the small-subunit ribosomal gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is especially true of microorganisms that are difficult to cultivate and are typically only represented in a single specimen5. Recent analysis of all genomes produced an unfinished draft of the Tree of Life. This includes a wide range of archaea, bacteria and other organisms that have not 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, assisting to determine if certain habitats require special protection. The information can be used in a variety of ways, from identifying the most effective remedies to fight diseases to enhancing crops. It is also useful for conservation efforts. It can help biologists identify areas that are most likely to have species that are cryptic, which could perform important metabolic functions and are susceptible to changes caused by humans. While funding to protect biodiversity are important, the best method to protect the world's biodiversity is to equip more people in developing nations with the knowledge they need to act locally and support conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) shows the relationships between organisms. Scientists can create an phylogenetic chart which shows the evolutionary relationship of taxonomic groups based on molecular data and morphological similarities or differences. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that have evolved from common ancestral. These shared traits could be homologous, or analogous. Homologous characteristics are identical in their evolutionary journey. Analogous traits could appear similar, but they do not share the same origins. Scientists group similar traits together into a grouping called a Clade. All members of a clade have a common trait, such as amniotic egg production. They all derived from an ancestor with these eggs. The clades are then connected to create a phylogenetic tree to determine which organisms have the closest relationship to.
To create a more thorough and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to establish the relationships between organisms. This data is more precise than morphological information and gives evidence of the evolutionary background of an organism or group. Molecular data allows researchers to identify the number of organisms who share an ancestor common to them and estimate their evolutionary age.
Phylogenetic relationships can be affected by a number of factors that include the phenomenon of phenotypicplasticity. This is a type behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to one species than another, obscuring the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous traits in the tree.
Furthermore, phylogenetics may aid in predicting the length and speed of speciation. This information can aid conservation biologists in making choices about which species to safeguard from extinction. In the end, it is the conservation of phylogenetic variety which will create an ecosystem that is balanced and complete.
Evolutionary Theory
The fundamental concept of evolution is that organisms develop distinct characteristics over time due to their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could develop according to its own needs and needs, 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 suggested that the usage or non-use of traits can lead to changes that can be passed on to future generations.
In the 1930s & 1940s, theories from various fields, such as genetics, natural selection, and particulate inheritance, merged to create a modern evolutionary theory. This defines how evolution occurs by the variation of genes in the population and how these variations alter over 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 advances in the field of evolutionary developmental biology have shown how variations can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction and the movement between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of a genotype over time) can result in evolution which is defined by change in the genome of the species over time and also by changes in phenotype as time passes (the expression of the genotype within the individual).
Students can better understand phylogeny by incorporating evolutionary thinking into all areas of biology. In a study by Grunspan and colleagues., it was shown 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 looking back, studying fossils, comparing species and studying living organisms. Evolution is not a distant moment; it is an ongoing process. Bacteria transform and resist antibiotics, viruses reinvent themselves and escape new drugs, and animals adapt their behavior to the changing environment. The changes that occur are often evident.
It wasn't until late 1980s that biologists realized that natural selection could be seen in action, as well. The key is that various characteristics result in different rates of survival and reproduction (differential fitness) and are passed from one generation to the next.
In the past, if a certain allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could be more common than any other allele. Over time, that would mean that the number of black moths in the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Monitoring evolutionary changes in action is easier when a species has a rapid generation turnover like bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples from each population are taken every day and more than 500.000 generations have passed.
Lenski's research has revealed 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 takes time--a fact that many find hard to accept.
Another example of microevolution is that mosquito genes that are resistant to pesticides are more prevalent in areas where insecticides are used. This is because the use of pesticides causes a selective pressure that favors people with resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance especially in a planet that is largely shaped by human activity. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding evolution will help you make better decisions regarding the future of the planet and its inhabitants.