The Academy's Evolution Site
The concept of biological evolution is among the most important concepts in biology. The Academies are involved in helping those who are interested in science to understand evolution theory and how it is incorporated in all areas of scientific research.
This site provides a wide range of sources for teachers, students and general readers of 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 represents the interconnectedness of all life. It is an emblem of love and harmony in a variety of cultures. It has numerous practical applications as well, such as 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 built on categorizing organisms based on their physical and metabolic characteristics. These methods rely on the collection of various 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 bacterial diversity is vastly underrepresented3,4.
In avoiding the necessity of direct observation and experimentation, genetic techniques have made it possible to depict the Tree of Life in a much more accurate way. We can construct trees using molecular techniques such as the small subunit ribosomal gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is especially the case for microorganisms which are difficult to cultivate and which are usually only present in a single sample5. A recent study of all genomes known to date has produced a rough draft version of the Tree of Life, including a large number of bacteria and archaea that have not been isolated, and which are not well understood.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, assisting to determine if certain habitats require special protection. This information can be used in a variety of ways, from identifying new treatments to fight disease to improving crop yields. The information is also useful to conservation efforts. It can aid biologists in identifying the areas that are most likely to contain cryptic species with potentially important metabolic functions that may be vulnerable to anthropogenic change. While conservation funds are important, the most effective method to preserve the biodiversity of the world is to equip more people in developing nations with the information they require to act locally and promote conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the connections between groups of organisms. Scientists can construct an phylogenetic chart which shows 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 biodiversity, genetics and evolution.
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 could be either homologous or analogous. Homologous characteristics are identical in terms of their evolutionary journey. Analogous traits may look like they are but they don't have the same origins. Scientists arrange similar traits into a grouping called a clade. For instance, all of the species in a clade share the characteristic of having amniotic egg and evolved from a common ancestor who had eggs. A phylogenetic tree can be built by connecting the clades to identify the species that are most closely related to each other.
Scientists use molecular DNA or RNA data to build a phylogenetic chart that is more accurate and precise. This information is more precise and gives evidence of the evolution history of an organism. Researchers can utilize Molecular Data to determine the evolutionary age of living organisms and discover how many organisms share a common ancestor.
에볼루션 슬롯게임 of a species can be affected by a number of factors, including phenotypicplasticity. This is a type behavior that changes as a result of specific environmental conditions. This can cause a trait to appear more similar to a species than another, obscuring the phylogenetic signals. This problem can be addressed by using cladistics. This is a method that incorporates the combination of homologous and analogous features in the tree.
In addition, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists decide the species they should safeguard from extinction. In the end, it's the conservation of phylogenetic variety that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms change over time as a result of their interactions with their environment. Several theories of evolutionary change have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve gradually according to its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that can be passed on to offspring.
In the 1930s and 1940s, concepts from a variety of fields--including genetics, natural selection, and particulate inheritance - came together to form the modern evolutionary theory synthesis which explains how evolution is triggered by the variations of genes within a population and how those variations change in time due to natural selection. This model, which encompasses genetic drift, mutations, gene flow and sexual selection, can be mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have revealed that variation can be introduced into a species through mutation, genetic drift, and reshuffling genes during sexual reproduction, and also by migration between populations. These processes, along with others, such as the directional selection process and the erosion of genes (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time as well as changes in the phenotype (the expression of genotypes within individuals).
Students can better understand the concept of phylogeny by using evolutionary thinking into all aspects of biology. In a recent study by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. For more information on how to teach about evolution, see The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily A Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species and studying living organisms. But evolution isn't just something that happened in the past; it's an ongoing process that is that is taking place right now. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of a changing world. The results 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 various characteristics result in different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.
In the past, if one allele - the genetic sequence that determines color - was present in a population of organisms that interbred, it could become more common than other allele. In time, this could mean that the number of moths that have black pigmentation in a population may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
The ability to observe evolutionary change is easier when a species has a rapid turnover of its generation, as with bacteria. 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 on a regular basis and more than 500.000 generations have passed.
Lenski's research has revealed that a mutation can profoundly alter the efficiency with the rate at which a population reproduces, and consequently the rate at which it changes. It also demonstrates that evolution takes time, which is hard for some to accept.
Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more prevalent in areas where insecticides have been used. This is because the use of pesticides causes a selective pressure that favors those who have resistant genotypes.
The rapidity of evolution has led to a greater awareness of its significance especially in a planet shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution can help us make better decisions regarding the future of our planet, and the lives of its inhabitants.