The Academy's Evolution Site

Biological evolution is a central 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 teachers, students and general readers with a range of learning resources on evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of life. It appears in many religions and cultures as a symbol of unity and love. It also has practical applications, like providing a framework to understand the evolution of species and how they respond to changes in environmental conditions.

Early attempts to represent the biological world were founded on categorizing organisms on their physical and metabolic characteristics. These methods depend on the collection of various parts of organisms or short fragments of DNA have greatly increased the diversity of a Tree of Life2. These trees are mostly populated by eukaryotes and bacteria are largely underrepresented3,4.

Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. In particular, molecular methods allow us to build trees using sequenced markers like the small subunit ribosomal RNA gene.

The Tree of Life has been dramatically expanded through genome sequencing. However there is still a lot of diversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate, and are typically found in a single specimen5. A recent analysis of all genomes produced a rough draft of the Tree of Life. This includes a wide range of archaea, bacteria and other organisms that haven't yet been isolated, or whose diversity has not been fully understood6.

This expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine whether specific habitats require special protection. This information can be utilized in a variety of ways, from identifying the most effective treatments to fight disease to enhancing crop yields. It is also beneficial for conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with potentially significant metabolic functions that could be vulnerable to anthropogenic change. Although funding to safeguard biodiversity are vital, ultimately the best way to preserve the world's biodiversity is for more people living in developing countries to be equipped with the knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between organisms. Using molecular data as well as morphological similarities and distinctions or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree which illustrates the evolution of taxonomic categories of homologous and analogous features in the tree.

Additionally, phylogenetics can help determine the duration and rate at which speciation occurs. This information can assist conservation biologists in making choices about which species to protect from disappearance. It is ultimately the preservation of phylogenetic diversity which will create a complete and balanced ecosystem.

Evolutionary Theory

The central theme in evolution is that organisms alter over time because of 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 a living thing would develop according to its own requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can cause changes that are passed on to the next generation.

In the 1930s and 1940s, ideas from a variety of fields--including natural selection, genetics, and particulate inheritance - came together to form the modern synthesis of evolutionary theory which explains how evolution occurs through the variations of genes within a population, and how those variations change over time due to natural selection. This model, which incorporates mutations, genetic drift, gene flow and 에볼루션바카라 sexual selection is mathematically described mathematically.

Recent developments in the field of evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, along with others, such as the directional selection process and the erosion of genes (changes in the frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time and changes in the phenotype (the expression of genotypes in an individual).

Students can better understand phylogeny by incorporating evolutionary thinking throughout all areas of biology. A recent study by Grunspan and 에볼루션 게이밍 colleagues, for instance demonstrated that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college-level biology course. For more information on how to teach evolution, see The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have looked at evolution through the past, 에볼루션카지노 studying fossils, and comparing species. They also observe living organisms. But evolution isn't just something that occurred in the past; it's an ongoing process, happening right now. Bacteria mutate and resist antibiotics, viruses re-invent themselves and elude new medications, and animals adapt their behavior in response to the changing environment. The changes that occur are often evident.

It wasn't until late-1980s that biologists realized that natural selection can be observed in action as well. The main reason is that different traits confer a different rate of survival as well as reproduction, and may be passed on from generation to generation.

In the past, if a certain allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could be more common than any other allele. In time, this could mean the number of black moths in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

The ability to observe evolutionary change is easier when a species has a fast generation turnover like bacteria. Since 1988, 에볼루션 바카라 무료 Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from one strain. Samples of each population have been collected regularly and more than 500.000 generations of E.coli have passed.

Lenski's research has shown that mutations can drastically alter the rate at which a population reproduces and, consequently the rate at which it changes. It also proves that evolution takes time, a fact that some people find hard 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 because the use of pesticides creates a pressure that favors individuals with resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance especially in a planet that is largely shaped by human activity. This includes climate change, pollution, and habitat loss, 에볼루션바카라 which prevents many species from adapting. Understanding the evolution process will help us make better choices about the future of our planet, as well as the life of its inhabitants.