The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies have been for a long time involved in helping people who are interested in science comprehend the theory of evolution and how it permeates all areas of scientific research.
This site provides students, teachers and general readers with a wide range 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 is used in many spiritual traditions and cultures as symbolizing unity and love. It also has many practical uses, like providing a framework for understanding the history of species and how they respond to changing environmental conditions.
The earliest attempts to depict the world of biology focused on separating organisms into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of living organisms or small DNA fragments, significantly expanded the diversity that could be included in the tree of life2. These trees are largely composed by eukaryotes, and bacteria are largely underrepresented3,4.
Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. Trees can be constructed by using molecular methods, such as the small-subunit ribosomal gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. This is particularly true for microorganisms, which can be difficult to cultivate and are often only represented in a single sample5. Recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a variety of archaea, bacteria and other organisms that have not yet been identified or the diversity of which is not well understood6.
This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if specific habitats require special protection. The information is useful in a variety of ways, such as finding new drugs, fighting diseases and enhancing crops. The information is also incredibly useful in conservation efforts. It helps biologists determine the areas most likely to contain cryptic species that could have important metabolic functions that could be vulnerable to anthropogenic change. Although funds to protect biodiversity are essential but the most effective way to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny (also called an evolutionary tree) illustrates the relationship between organisms. Scientists can construct an phylogenetic chart which shows the evolutionary relationships between taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is crucial in understanding biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar traits and evolved from an ancestor that shared traits. These shared traits may be homologous, or analogous. Homologous characteristics are identical in their evolutionary paths. Analogous traits may look similar, but they do not have the same ancestry. Scientists arrange similar traits into a grouping known as a the clade. Every organism in a group have a common characteristic, like amniotic egg production. They all came from an ancestor who had these eggs. The clades then join to form a phylogenetic branch to determine the organisms with the closest relationship to.
To create a more thorough 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 evolutionary history of an organism. The analysis of molecular data can help researchers determine the number of species that share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships between organisms can be influenced by several factors including phenotypic plasticity, a kind of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar in one species than another, clouding the phylogenetic signal. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous features in the tree.
In addition, phylogenetics can aid in predicting the length and speed of speciation. This information can assist conservation biologists make decisions about which species they should protect from the threat of extinction. 에볼루션게이밍 is ultimately the preservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme of evolution is that organisms acquire various characteristics over time due to their interactions with their environments. Many theories of evolution have been developed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that can be passed on to offspring.
In the 1930s and 1940s, concepts from various fields, such as genetics, natural selection, and particulate inheritance, merged to form a contemporary evolutionary theory. This defines how evolution is triggered by the variations in genes within the population and how these variants alter over time due to natural selection. This model, which encompasses mutations, genetic drift in gene flow, and sexual selection, can be mathematically described.
Recent advances in evolutionary developmental biology have shown how variation can be introduced to a species through genetic drift, mutations or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time) can lead to evolution, which is defined by changes in the genome of the species over time and also by changes in phenotype as time passes (the expression of that genotype in an individual).
Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny as well as evolution. In a study by Grunspan et al. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution in the course of a college biology. For more information about how to teach evolution read The Evolutionary Potential 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 by looking in the past, studying fossils, and comparing species. They also study living organisms. But evolution isn't just something that happened in the past. It's an ongoing process that is happening today. Bacteria evolve and resist antibiotics, viruses evolve and are able to evade new medications and animals alter their behavior in response to the changing environment. The results are usually evident.
It wasn't until the late 1980s when biologists began to realize that natural selection was in play. The key is that various traits confer different rates of survival and reproduction (differential fitness) and can be passed down from one generation to the next.
In the past when one particular allele--the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it could quickly become more common than other alleles. As time passes, that could mean 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.
Observing evolutionary change in action is easier when a particular species has a rapid turnover of its generation such as bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each population are taken every day, and over fifty thousand generations have been observed.
Lenski's research has shown that a mutation can profoundly alter the rate at which a population reproduces and, consequently, the rate at which it changes. It also demonstrates that evolution takes time, which is difficult for some to accept.
Another example of microevolution is how mosquito genes that are resistant to pesticides appear more frequently in populations in which insecticides are utilized. That's because the use of pesticides creates a pressure that favors individuals who have resistant genotypes.
The rapid pace at which evolution takes place has led to an increasing appreciation of its importance in a world shaped by human activity--including climate changes, pollution and the loss of habitats that hinder many species from adapting. Understanding evolution can help us make smarter decisions about the future of our planet as well as the lives of its inhabitants.