The Academy's Evolution Site

Biological evolution is one of the most important concepts in biology. The Academies are committed to helping those interested in the sciences learn about the theory of evolution and how it is incorporated in all areas of scientific research.

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

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is a symbol of love and unity in many cultures. It also has practical uses, like providing a framework to understand 에볼루션 바카라사이트 the history of species and how they react to changing environmental conditions.

The first attempts at depicting the biological world focused on separating species into distinct categories that were identified by their physical and metabolic characteristics1. These methods, which depend on the sampling of different parts of organisms or short DNA fragments, have significantly increased the diversity of a tree of Life2. These trees are mostly populated of eukaryotes, while 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. We can create trees by using molecular methods, such as the small-subunit ribosomal gene.

Despite the rapid 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 produced a rough draft of a 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, assisting to determine if specific habitats require special protection. This information can be used in a variety of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of crops. The information is also incredibly valuable for conservation efforts. It can aid biologists in identifying the areas that are most likely to contain cryptic species with potentially important metabolic functions that may be at risk of anthropogenic changes. While funds to safeguard biodiversity are vital but the most effective way to preserve the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between different organisms. Scientists can construct an phylogenetic chart which shows the evolution of taxonomic groups based on molecular data and morphological differences or similarities. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms with similar traits and have evolved from an ancestor that shared traits. These shared traits could be analogous, 에볼루션 바카라사이트 or 에볼루션 코리아 homologous. Homologous traits are similar in terms of their evolutionary journey. Analogous traits may look like they are however they do not have the same origins. Scientists group similar traits together into a grouping referred to as a clade. For example, 에볼루션 슬롯 all of the organisms in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor that had eggs. The clades are then connected to form a phylogenetic branch that can determine the organisms with the closest relationship.

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

The phylogenetic relationships of a species can be affected by a number of factors, including the phenotypic plasticity. This is a type of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more resembling to one species than to the other and obscure the phylogenetic signals. However, this problem can be cured by the use of methods such as cladistics which combine similar and homologous traits into the tree.

In addition, phylogenetics can aid in predicting the length and speed of speciation. This information can aid conservation biologists to decide the species they should safeguard from extinction. In the end, it is 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. A variety of theories about evolution have been developed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that could be passed on to offspring.

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

Recent discoveries in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species by mutation, genetic drift, and reshuffling of genes during sexual reproduction, as well as through migration between populations. These processes, as well as others such as directional selection and gene erosion (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time, as well as changes in the phenotype (the expression of genotypes within individuals).

Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny as well as evolution. A recent study conducted by Grunspan and 무료 에볼루션 colleagues, for example revealed that teaching students about the evidence supporting evolution helped students accept the concept of evolution in a college biology class. For more information on how to teach about evolution, please read The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by looking back--analyzing fossils, comparing species, and observing living organisms. But evolution isn't a thing that occurred in the past. It's an ongoing process that is happening right now. Bacteria mutate and resist antibiotics, viruses reinvent themselves and are able to evade new medications and animals change their behavior to the changing climate. The changes that result are often easy to see.

It wasn't until the late 1980s that biologists began realize that natural selection was also in action. The key is that different characteristics result in different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.

In the past, if one particular allele - the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it might quickly become more common than other alleles. As time passes, that could mean the number of black moths within a 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 observe evolution when an organism, like bacteria, has a rapid generation turnover. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples of each are taken every day and more than 50,000 generations have now passed.

Lenski's research has revealed that mutations can alter the rate of change and the effectiveness at which a population reproduces. It also shows that evolution takes time, something that is difficult for some to accept.

Another example of microevolution is that mosquito genes for resistance to pesticides show up more often in areas where insecticides are used. This is because pesticides cause an enticement that favors those who have resistant genotypes.

The speed at which evolution can take place has led to a growing appreciation of its importance in a world that is shaped by human activities, including climate change, pollution and the loss of habitats which prevent many species from adjusting. Understanding evolution will help us make better decisions regarding the future of our planet and the life of its inhabitants.