The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies are committed to helping those interested in science understand evolution theory and how it is incorporated in all areas of scientific research.

This site provides students, teachers and general readers with a range of learning resources on evolution. It includes the most important video clips from NOVA and WGBH's science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and unity in many cultures. It can be used in many practical ways in addition to providing a framework for understanding the history of species and how they react to changing environmental conditions.

The earliest attempts to depict the world of biology focused on separating species into distinct categories that were distinguished by physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms or sequences of small fragments of their DNA, significantly increased the variety that could be included in a tree of life2. These trees are largely composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

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 enable us to create trees using sequenced markers like the small subunit ribosomal RNA gene.

Despite the massive expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are often only present in a single specimen5. A recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that have not yet been isolated or their diversity is not fully understood6.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine if certain habitats require protection. The information is useful in a variety of ways, such as identifying new drugs, combating diseases and enhancing crops. 에볼루션 사이트 is also incredibly beneficial to conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species with potentially important metabolic functions that could be at risk of anthropogenic changes. While conservation funds are essential, the best method to preserve the world's biodiversity is to equip more people in developing nations with the information they require to act locally and promote conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between different organisms. Scientists can create an phylogenetic chart which shows the evolutionary relationship of taxonomic categories using molecular information and morphological similarities or differences. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.

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 can be either homologous or analogous. Homologous traits are the same in terms of their evolutionary journey. Analogous traits might appear like they are but they don't share the same origins. Scientists put similar traits into a grouping referred to as a the clade. All organisms in a group have a common characteristic, for example, amniotic egg production. They all came from an ancestor with these eggs. The clades are then linked to form a phylogenetic branch to determine which organisms have the closest relationship.

To create a more thorough and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to determine the connections between organisms. This information is more precise and gives evidence of the evolution history of an organism. Researchers can utilize Molecular Data to determine the age of evolution of organisms and identify how many organisms share a common ancestor.

mouse click the following article of organisms can be affected by a variety of factors including phenotypic plasticity, an aspect of behavior that changes in response to specific environmental conditions. This can cause a particular trait to appear more similar in one species than another, obscuring the phylogenetic signal. However, this problem can be solved through the use of methods such as cladistics which combine homologous and analogous features into the tree.

Additionally, phylogenetics can aid in predicting the duration and rate of speciation. This information can aid conservation biologists to make decisions about which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity which will lead to an ecologically balanced and complete ecosystem.

Evolutionary Theory

The main idea behind evolution is that organisms change over time as a result of their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could develop according to its own needs as well as 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

In the 1930s and 1940s, theories from various areas, including genetics, natural selection, and particulate inheritance, merged to form a contemporary 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, which encompasses genetic drift, mutations in gene flow, and sexual selection can be mathematically described mathematically.


Recent developments in evolutionary developmental biology have shown how variations can be introduced to a species by mutations, genetic drift and reshuffling of genes during sexual reproduction and 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 changes in the genome of the species over time, and also the change in phenotype over time (the expression of the genotype in an individual).

Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. In a recent study conducted by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution boosted their understanding of evolution in a college-level course in biology. For more information on how to teach about evolution, please read The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution by looking in the past, analyzing fossils and comparing species. They also observe living organisms. However, evolution isn't something that happened in the past; it's an ongoing process, taking place right now. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of a changing world. The resulting changes are often evident.

But it wasn't until the late 1980s that biologists understood that natural selection can be seen in action, as well. The key is the fact that different traits result in a different rate of survival and reproduction, and they can be passed down from one generation to another.

In the past when one particular allele--the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it might rapidly become more common than other alleles. Over time, this would 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.

It is easier to track evolution when a species, such as bacteria, has a high generation turnover. 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 over fifty thousand generations have been observed.

Lenski's research has shown that a mutation can profoundly alter the rate at the rate at which a population reproduces, and consequently the rate at which it changes. It also demonstrates that evolution is slow-moving, a fact that many are unable to accept.

Another example of microevolution is how mosquito genes that are resistant to pesticides show up more often in populations where insecticides are used. That's because the use of pesticides causes a selective pressure that favors people with resistant genotypes.

The rapidity of evolution has led to a growing recognition of its importance, especially in a world which is largely shaped by human activities. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding evolution can help us make smarter choices about the future of our planet as well as the life of its inhabitants.