The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies have been active for a long time in helping people who are interested in science comprehend the concept of evolution and how it influences every area of scientific inquiry.

This site provides teachers, students and general readers with a wide range of educational resources on evolution. It also includes important video clips from NOVA and 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 unity in many cultures. It can be used in many practical ways as well, including providing a framework to understand the history of species and how they react to changes in environmental conditions.

The earliest attempts to depict the biological world focused on separating organisms into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, which are based on the sampling of different parts of organisms or DNA fragments, have greatly increased the diversity of a tree of Life2. These trees are mostly populated by eukaryotes, and bacteria are largely underrepresented3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. In particular, molecular methods allow us to construct 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 especially true of microorganisms that are difficult to cultivate and are usually only found in a single sample5. A recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a wide range of archaea, bacteria and 에볼루션 바카라사이트 other organisms that have not yet been identified or the diversity of which is not fully understood6.

The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine if specific habitats require protection. The information can be used in a variety of ways, from identifying new treatments to fight disease to improving crop yields. It is also beneficial in conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species that could have significant metabolic functions that could be at risk of anthropogenic changes. Although funds to safeguard biodiversity are vital however, the most effective method to protect the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, 에볼루션 바카라 무료체험 illustrates the connections between various groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic groups based on molecular data and morphological similarities or differences. Phylogeny is essential in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms with similar traits and evolved from an ancestor that shared traits. These shared traits can be either homologous or analogous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear similar but do not have the identical origins. Scientists combine similar traits into a grouping called a clade. Every organism in a group share a trait, such as amniotic egg production. They all evolved from an ancestor that had these eggs. A phylogenetic tree can be constructed by connecting the clades to identify the organisms that are most closely related to each other.

Scientists use molecular DNA or RNA data to construct a phylogenetic graph that is more accurate and detailed. This information is more precise than the morphological data and provides evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to calculate the evolutionary age of organisms and determine how many species share an ancestor common to all.

The phylogenetic relationship can be affected by a variety of factors such as the phenotypic plasticity. This is a type behavior that alters as a result of specific environmental conditions. This can cause a trait to appear more like a species another, obscuring the phylogenetic signal. However, this problem can be solved through the use of methods such as cladistics that include a mix of analogous and homologous features into the tree.

In addition, phylogenetics helps predict the duration and rate at which speciation takes place. This information can help conservation biologists make decisions about which species to protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms develop various characteristics over time due to their interactions with their environment. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would develop according to its own needs, 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 use or absence of traits can cause changes that are passed on to the next generation.

In the 1930s and 1940s, concepts from various areas, including genetics, natural selection and particulate inheritance, were brought together to form a modern synthesis of evolution theory. This defines how evolution happens through the variation in genes within the population and how these variants alter over time due to natural selection. This model, known as genetic drift, mutation, 에볼루션 룰렛 gene flow, and sexual selection, is the foundation of the current evolutionary biology and can be mathematically described.

Recent advances in the field of evolutionary developmental biology have demonstrated how variation can be introduced to a species via mutations, genetic drift, reshuffling genes during 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 change in the genome of the species over time and also by changes in phenotype over time (the expression of the genotype within the individual).

Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny and evolutionary. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence for 에볼루션 evolution increased students' acceptance of evolution in a college-level biology course. For more information on how to teach evolution look up The Evolutionary Power of Biology 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, 에볼루션 룰렛 comparing species, and observing living organisms. But evolution isn't just something that happened in the past; it's an ongoing process that is happening in the present. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior because of the changing environment. The results are usually visible.

It wasn't until late 1980s that biologists realized that natural selection can be observed in action as well. The reason is that different traits confer different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.

In the past, when one particular allele - the genetic sequence that controls coloration - was present in a population of interbreeding species, it could rapidly become more common than the other alleles. In time, this could mean that the number of black moths within the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to see evolutionary change when the species, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from one strain. Samples from each population have been collected regularly and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's research has revealed that a mutation can dramatically alter the efficiency with the rate at which a population reproduces, and consequently the rate at which it evolves. It also shows that evolution takes time, something that is hard for some to accept.

Another example of microevolution is the way mosquito genes that are resistant to pesticides show up more often in populations where insecticides are used. This is due to pesticides causing an enticement that favors those who have resistant genotypes.

The rapid pace of evolution taking place has led to a growing awareness of its significance in a world shaped by human activities, including climate change, pollution, and the loss of habitats that hinder the species from adapting. Understanding evolution will help us make better choices about the future of our planet, as well as the life of its inhabitants.