The Academy's Evolution Site

The concept of biological evolution is among the most central concepts in biology. The Academies are involved in helping those who are interested in science comprehend the evolution theory and how it can be applied in all areas of scientific research.

This site provides students, teachers and general readers with a range of educational resources on evolution. It includes key video clips from NOVA and WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of all life. It is seen in a variety of religions and cultures as a symbol of unity and love. It has numerous practical applications in addition to 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 categorizing species into distinct categories that had been identified by their physical and metabolic characteristics1. These methods, based on the sampling of different parts of living organisms, or small fragments of their DNA significantly increased the variety that could be included in a tree of life2. These trees are mostly populated of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

By avoiding the necessity for direct observation and experimentation, genetic techniques have allowed us to depict the Tree of Life in a more precise manner. We can construct trees by using molecular methods, such as the small-subunit ribosomal gene.

Despite the massive growth of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is especially true of microorganisms, which can be difficult to cultivate and are often only represented in a single sample5. Recent analysis of all genomes has produced an unfinished draft of the Tree of Life. This includes a large number of bacteria, archaea and other organisms that haven't yet been isolated, or the diversity of which is not fully understood6.

This expanded Tree of Life can be used to determine the diversity of a particular area and determine if particular habitats need special protection. This information can be used in a variety of ways, from identifying new remedies to fight diseases to improving the quality of crops. The information is also useful in conservation efforts. 에볼루션 게이밍 can help biologists identify the areas most likely to contain cryptic species with potentially important metabolic functions that could be vulnerable to anthropogenic change. Although funding to protect biodiversity are essential, ultimately the best way to protect the world's biodiversity is for more people living 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) shows the relationships between different organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic groups using molecular data and morphological similarities or differences. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits could be homologous, or analogous. 에볼루션 바카라 무료체험 are identical in their evolutionary origins, while analogous traits look like they do, but don't have the same ancestors. Scientists put similar traits into a grouping known as a the clade. All members of a clade have a common characteristic, like amniotic egg production. They all came from an ancestor that had these eggs. The clades are then connected to form a phylogenetic branch to determine which organisms have 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 morphological information and provides evidence of the evolutionary history of an organism or group. The analysis of molecular data can help researchers determine the number of organisms that have a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships between species can be affected by a variety of factors including phenotypic plasticity, a type of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more resembling to one species than another which can obscure the phylogenetic signal. However, this issue can be solved through the use of methods like cladistics, which incorporate a combination of similar and homologous traits into the tree.

Additionally, phylogenetics aids determine the duration and rate of speciation. This information can assist conservation biologists make decisions about the species they should safeguard from the threat of extinction. In the end, it's the conservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms develop different features over time based on their interactions with their surroundings. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would develop according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can lead to changes that are passed on to the next generation.

In the 1930s & 1940s, concepts from various areas, including genetics, natural selection and particulate inheritance, came together to form a modern evolutionary theory. This describes how evolution happens through the variation in genes within the population, and how these variants change with time due to natural selection. This model, known as genetic drift or mutation, gene flow and sexual selection, is a key element of the current evolutionary biology and is mathematically described.

Recent developments in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species by mutation, genetic drift, and reshuffling of genes in sexual reproduction, and also through the movement of populations. These processes, in conjunction with others such as the directional selection process and the erosion of genes (changes in frequency of genotypes over time) can lead to 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 phylogeny by incorporating evolutionary thinking into all areas of biology. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence supporting evolution increased students' understanding of evolution in a college-level biology class. For more details about 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

Scientists have studied evolution through looking back in the past, analyzing fossils and comparing species. They also study living organisms. However, evolution isn't something that occurred in the past; it's an ongoing process that is taking place right now. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior in the wake of a changing world. The changes that result are often evident.

It wasn't until the 1980s that biologists began realize that natural selection was in action. The reason is that different traits confer 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 group of interbreeding organisms, it might quickly become more common than the other alleles. Over time, this would mean that the number of moths with black pigmentation in a group could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Observing evolutionary change in action is easier when a species has a rapid turnover of its generation like bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. The samples of each population have been taken regularly, and more than 50,000 generations of E.coli have passed.

Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the effectiveness of a population's reproduction. It also shows that evolution is slow-moving, a fact that some find difficult to accept.

Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more common in populations that have used insecticides. This is due to the fact that the use of pesticides creates a pressure that favors individuals who have resistant genotypes.

The rapidity of evolution has led to a growing awareness of its significance especially in a planet that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution can assist you in making better choices regarding the future of the planet and its inhabitants.