The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have long been involved in helping people who are interested in science understand the concept of evolution and how it permeates every area of scientific inquiry.
This site provides a wide range of sources for students, teachers and general readers of 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. 에볼루션카지노 can be used in many practical ways as well, including providing a framework to understand the evolution of species and how they react to changes in environmental conditions.
The first attempts to depict the world of biology were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which relied on the sampling of different parts of living organisms or sequences of short fragments of their DNA, greatly increased the variety of organisms that could be included in a tree of life2. However the trees are mostly comprised of eukaryotes, and bacterial diversity is still largely unrepresented3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to build trees by using sequenced markers like the small subunit of ribosomal RNA gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true for microorganisms, which are difficult to cultivate and are usually only present in a single specimen5. A recent analysis of all genomes known to date has produced a rough draft of the Tree of Life, including many archaea and bacteria that have not been isolated and whose diversity is poorly understood6.
The expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if certain habitats require special protection. This information can be utilized in a range of ways, from identifying the most effective treatments to fight disease to improving the quality of crops. This information is also beneficial for conservation efforts. 에볼루션게이밍 can help biologists identify those areas that are most likely contain cryptic species that could have significant metabolic functions that could be at risk of anthropogenic changes. Although funding to protect biodiversity are crucial however, the most effective method to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, illustrates the connections between groups of organisms. By using molecular information as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree which illustrates the evolutionary relationships between taxonomic groups. The phylogeny of a tree plays an important role in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestors. These shared traits may be analogous or homologous. Homologous traits are similar in their evolutionary origins, while analogous traits look like they do, but don't have the same origins. Scientists combine similar traits into a grouping called a Clade. For instance, all the organisms that make up a clade share the characteristic of having amniotic egg and evolved from a common ancestor who had these eggs. A phylogenetic tree is then constructed by connecting clades to determine the organisms who are the closest to each other.
For a more precise and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to establish the relationships between organisms. This information is more precise than the morphological data and gives evidence of the evolutionary history of an individual or group. Molecular data allows researchers to determine the number of species that share the same ancestor and estimate their evolutionary age.
Phylogenetic relationships can be affected by a variety of factors, including phenotypicplasticity. This is a type of behavior that alters as a result of unique environmental conditions. This can cause a characteristic to appear more similar to a species than to the other, obscuring the phylogenetic signals. However, this problem can be cured by the use of methods such as cladistics which incorporate a combination of homologous and analogous features into the tree.
Additionally, phylogenetics aids determine the duration and speed of speciation. This information can aid conservation biologists in making choices about which species to protect from the threat of extinction. In the end, it is the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept of evolution is that organisms develop distinct characteristics over time based on their interactions with their environments. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its individual needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can lead to changes that can be passed on to future generations.
In the 1930s and 1940s, concepts from various fields, such as genetics, natural selection, and particulate inheritance, came together to create a modern evolutionary theory. This describes how evolution happens through the variation in genes within the population and how these variations alter over time due to natural selection. This model, known as genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of the current evolutionary biology and is mathematically described.
Recent developments in the field of evolutionary developmental biology have shown that variation can be introduced into a species through mutation, genetic drift, and reshuffling of genes in sexual reproduction, and also through migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution which is defined by change in the genome of the species over time, and also by changes in phenotype over time (the expression of the genotype in the individual).
Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking throughout all aspects of biology. In a recent study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution during an undergraduate biology course. For more information on how to teach about evolution, please see The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back--analyzing fossils, comparing species and observing living organisms. Evolution isn't a flims event, but an ongoing process. Bacteria mutate and resist antibiotics, viruses reinvent themselves and elude new medications, and animals adapt their behavior to the changing climate. The changes that result are often easy to see.
However, it wasn't until late-1980s that biologists realized that natural selection can be seen in action, as well. The key is that various traits have different rates of survival and reproduction (differential fitness) and are passed 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 species, it could quickly become more common than all other alleles. In time, this could mean that the number of black moths within 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 observe evolution when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from a single strain. Samples from each population have been collected frequently and more than 500.000 generations of E.coli have passed.
Lenski's research has revealed that a mutation can profoundly alter the speed at which a population reproduces and, consequently, the rate at which it changes. It also shows that evolution takes time, a fact that some people 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 employed. That's because the use of pesticides creates a pressure that favors people who have resistant genotypes.
The rapidity of evolution has led to an increasing appreciation of its importance particularly in a world which is largely shaped by human activities. This includes climate change, pollution, and habitat loss that hinders many species from adapting. Understanding evolution can assist you in making better choices about the future of our planet and its inhabitants.