The Academy's Evolution Site
Biology is a key concept in biology. The Academies are involved in helping those interested in the sciences comprehend the evolution theory and how it can be applied in all areas of scientific research.
This site provides a wide range of tools for teachers, students and general readers of evolution. It contains important video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is a symbol of love and harmony in a variety of cultures. It has many practical applications as well, such as providing a framework to understand the history of species and how they react to changes in environmental conditions.
Early attempts to represent the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely 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 represented in a tree of life2. These trees are mostly populated by eukaryotes, and bacteria are largely underrepresented3,4.
By avoiding the necessity for direct observation and experimentation genetic techniques have made it possible to represent the Tree of Life in a much more accurate way. Particularly, molecular techniques enable us to create trees by using sequenced markers such as the small subunit of ribosomal RNA gene.
The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are usually found in a single specimen5. A recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a variety of archaea, bacteria and other organisms that haven't yet been identified or the diversity of which is not well understood6.
The expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine if certain habitats require protection. The information is useful in a variety of ways, such as finding new drugs, battling diseases and improving crops. It is also valuable in conservation efforts. It can help biologists identify the areas most likely to contain cryptic species that could have significant metabolic functions that could be vulnerable to anthropogenic change. Although funds to protect biodiversity are essential, ultimately the best way to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny (also known as an evolutionary tree) shows the relationships between different organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationship of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from a common ancestor. These shared traits may be analogous, or homologous. Homologous traits are similar in terms of their evolutionary path. Analogous traits could appear like they are but they don't have the same origins. Scientists arrange similar traits into a grouping called a the clade. For instance, all the organisms that make up a clade share the trait of having amniotic eggs. They evolved from a common ancestor who had these eggs. The clades then join to create a phylogenetic tree to determine the organisms with the closest connection to each other.
For a more precise and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the connections between organisms. This data is more precise than the morphological data and gives evidence of the evolutionary background of an organism or group. The use of molecular data lets researchers determine the number of species that share a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships between organisms can be influenced by several factors including phenotypic plasticity, a type of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another, obscuring the phylogenetic signal. However, this problem can be reduced by the use of techniques like cladistics, which incorporate a combination of homologous and analogous features into the tree.
Additionally, phylogenetics aids determine the duration and speed at which speciation takes place. This information can aid conservation biologists to make decisions about the species they should safeguard from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity that will create an ecologically balanced and complete ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms change over time due to their interactions with their environment. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can cause changes that are passed on to the
In the 1930s and 1940s, concepts from various areas, including natural selection, genetics & particulate inheritance, were brought together to form a modern synthesis of evolution theory. This describes how evolution occurs by 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 current evolutionary biology, and is mathematically described.
Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species through genetic drift, mutation, and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution which is defined by change in the genome of the species over time and the change in phenotype over time (the expression of the genotype in the individual).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. In a recent study conducted by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution boosted their understanding of evolution in the course of a college biology. To learn more about 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 studying fossils, comparing species and observing living organisms. But evolution isn't just something that occurred in the past; it's an ongoing process, happening in the present. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior in the wake of a changing environment. The changes that result are often evident.
It wasn't until the late 1980s that biologists began to realize that natural selection was at work. The key is that various traits confer different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.
In the past, if one particular allele--the genetic sequence that controls coloration - was present in a population of interbreeding organisms, it could quickly become more prevalent than other alleles. Over time, this would mean that the number of moths with 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.
It is easier to observe evolution when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from one strain. Samples of each population were taken regularly and more than 50,000 generations of E.coli have passed.
Lenski's research has revealed that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows that evolution takes time, a fact that some people are unable to accept.
Another example of microevolution is that mosquito genes that are resistant to pesticides show up more often in populations where insecticides are used. This is because the use of pesticides creates a selective pressure that favors those with resistant genotypes.
에볼루션 무료 바카라 at which evolution can take place has led to a growing awareness of its significance in a world shaped by human activities, including climate changes, pollution and the loss of habitats that hinder many species from adjusting. Understanding the evolution process can help us make smarter choices about the future of our planet, as well as the life of its inhabitants.