The Academy's Evolution Site

Biological evolution is one of the most important concepts in biology. The Academies are committed to helping those who are interested in science to learn about the theory of evolution and how it is permeated throughout all fields of scientific research.

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

Tree of Life

The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is an emblem of love and unity in many cultures. It has numerous practical applications as well, such as providing a framework for understanding the history of species, and how they react to changing environmental conditions.

The first attempts at depicting the world of biology focused on the classification of organisms into distinct categories which were distinguished by physical and metabolic characteristics1. These methods, which are based on the sampling of different parts of organisms or fragments of DNA have greatly increased the diversity of a Tree of Life2. These trees are mostly populated of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the requirement for 에볼루션 direct observation and experimentation. Particularly, molecular techniques allow us to construct trees by using sequenced markers, such as the small subunit ribosomal gene.

Despite the dramatic growth of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is especially relevant to microorganisms that are difficult to cultivate and are typically found in a single specimen5. A recent analysis of all genomes known to date has created a rough draft of the Tree of Life, including a large number of archaea and bacteria that have not been isolated and whose diversity is poorly understood6.

This expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine if specific habitats require protection. This information can be used in a variety of ways, including finding new drugs, battling diseases and improving crops. The information is also valuable to conservation efforts. It can aid biologists in identifying areas most likely to have cryptic species, which could perform important metabolic functions and be vulnerable to changes caused by humans. While funding to protect biodiversity are important, the best way to conserve the biodiversity of the world is to equip more people in developing nations with the information they require to act locally and support conservation.

Phylogeny

A phylogeny, also called an evolutionary tree, reveals the relationships between groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological similarities or differences. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and evolved from a common ancestor. These shared traits could be either analogous or homologous. Homologous traits are similar in their evolutionary path. Analogous traits could appear like they are but they don't have the same origins. Scientists group similar traits into a grouping called a the clade. Every organism in a group have a common characteristic, like amniotic egg production. They all evolved from an ancestor with these eggs. A phylogenetic tree is built by connecting the clades to identify the organisms which are the closest to one another.

For a more detailed and 에볼루션게이밍 accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to establish the connections between organisms. This information is more precise and provides evidence of the evolutionary history of an organism. The analysis of molecular data can help researchers determine the number of organisms that have an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships between organisms are influenced by many factors, including phenotypic flexibility, a kind of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to one species than to the other, obscuring the phylogenetic signals. However, this problem can be reduced by the use of methods such as cladistics that incorporate a combination of analogous and homologous features into the tree.

Additionally, phylogenetics can help determine the duration and rate at which speciation occurs. This information can assist conservation biologists in deciding which species to safeguard from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.

Evolutionary Theory

The central theme in evolution is that organisms change over time as a result of their interactions with their environment. Several theories of evolutionary change have been developed by a wide range of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits causes changes that can be passed on to the offspring.

In the 1930s and 1940s, theories from various fields, including genetics, natural selection, and particulate inheritance--came together to create the modern synthesis of evolutionary theory, which defines how evolution happens through the variations of genes within a population and how those variations change over time as a result of natural selection. This model, known as genetic drift or mutation, gene flow, and sexual selection, is a key element of modern evolutionary biology and can be mathematically explained.

Recent discoveries in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species by mutation, genetic drift, and reshuffling of genes during sexual reproduction, and also through migration between populations. These processes, along with others 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 in an individual).

Incorporating evolutionary thinking into all aspects of biology education can improve students' understanding of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for instance, showed that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college biology class. For more details about 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

Traditionally scientists have studied evolution through looking back, studying fossils, comparing species, and observing living organisms. Evolution is not a distant event; it is an ongoing process. Viruses evolve to stay away from new drugs and 에볼루션 바카라 bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of a changing world. The changes that result are often evident.

But it wasn't until the late-1980s that biologists realized that natural selection could be seen in action, as well. The key is that various traits confer different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.

In the past when one particular allele--the genetic sequence that defines color in a group of interbreeding species, it could quickly become more common than other alleles. As time passes, this could mean that the number of moths sporting black pigmentation 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 much easier when a species has a rapid turnover of its generation like bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from one strain. The samples of each population have been collected regularly and more than 50,000 generations of E.coli have been observed to have passed.

Lenski's work has shown that mutations can alter the rate of change and the rate of a population's reproduction. It also shows that evolution takes time, a fact that some people find hard 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. That's because the use of pesticides creates a selective pressure that favors people with resistant genotypes.

The rapidity of evolution has led to a greater awareness of its significance particularly in a world that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding evolution can help us make smarter choices about the future of our planet, 무료 에볼루션 블랙잭 (https://myaccount.signin.mygovscot.org/CASServer/logout?redirectURL=Https://evolutionkr.kr) and the lives of its inhabitants.