The Academy's Evolution Site

Biology is a key concept in biology. The Academies are committed to helping those who are interested in the sciences understand evolution theory and how it is permeated throughout all fields of scientific research.

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

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of life. It is seen in a variety of cultures and spiritual beliefs as an emblem of unity and love. It also has important practical uses, like providing a framework to understand the history of species and how they react to changes in the environment.

Early approaches to depicting the world of biology focused on categorizing organisms into distinct categories that were identified by their physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of living organisms or short fragments of their DNA, significantly increased the variety that could be included in a tree of life2. These trees are largely composed by eukaryotes, and bacterial diversity is vastly underrepresented3,4.

Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. We can construct trees by using molecular methods such as the small subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of diversity to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are usually only represented in a single specimen5. A recent analysis of all genomes has produced an initial draft of a Tree of Life. This includes a wide range of bacteria, archaea and other organisms that have not yet been isolated, or whose diversity has not been fully understood6.

This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if specific habitats require protection. This information can be utilized in a variety of ways, from identifying the most effective remedies to fight diseases to improving crops. This information is also extremely useful for conservation efforts. It can help biologists identify areas that are likely to have cryptic species, which could have vital metabolic functions, and could be susceptible to human-induced change. While conservation funds are important, the best method to protect the world's biodiversity is to empower more people in developing nations with the information they require to take action locally and encourage conservation.

Phylogeny

A phylogeny, also called an evolutionary tree, illustrates the relationships between different groups of organisms. Scientists can construct an phylogenetic chart which shows the evolution of taxonomic groups using molecular data and morphological differences or similarities. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship 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 their evolutionary journey. Analogous traits could appear like they are, but they do not have the same origins. Scientists group similar traits into a grouping known as a clade. Every organism in a group have a common characteristic, for example, amniotic egg production. They all derived from an ancestor with these eggs. A phylogenetic tree can be constructed by connecting the clades to determine the organisms who are the closest to each other.

Scientists use DNA or RNA molecular data to construct a phylogenetic graph which is more precise and detailed. This information is more precise than morphological information and gives evidence of the evolutionary background of an organism or group. The analysis of molecular data can help researchers determine the number of species that share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationship can be affected by a variety of factors that include the phenomenon of phenotypicplasticity. This is a type of behavior that alters as a result of unique environmental conditions. This can make a trait appear more similar to one species than another and obscure the phylogenetic signals. However, this issue can be reduced by the use of methods such as cladistics that include a mix of similar and homologous traits into the tree.

In addition, phylogenetics can help predict the time and pace of speciation. This information can assist conservation biologists in making choices about which species to save from extinction. In the end, it is the preservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

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

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

Recent developments in evolutionary developmental biology have demonstrated how variations can be introduced to a species through genetic drift, mutations, reshuffling genes during sexual reproduction and the movement between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of the genotype over time) can lead to evolution that is defined as change in the genome of the species over time and also by changes in phenotype as time passes (the expression of the genotype in an individual).

Students can better understand the concept of phylogeny by using evolutionary thinking throughout all aspects of biology. In a study by Grunspan et al. It was found that teaching students about the evidence for evolution increased their understanding of evolution during an undergraduate biology course. For more details on how to teach evolution look up The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.


에볼루션 블랙잭 in Action

Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species and studying living organisms. Evolution is not a distant event; it is an ongoing process. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior in the wake of a changing environment. The results are often apparent.

It wasn't until late 1980s that biologists understood that natural selection could be observed in action as well. The key is the fact that different traits result in an individual rate of survival as well as reproduction, and may be passed on from generation to generation.

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

Observing evolutionary change in action is easier when a particular species has a fast generation turnover such as bacteria. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples from each population are taken on a regular basis and more than 50,000 generations have now passed.

Lenski's research has revealed that mutations can alter the rate of change and the efficiency at which a population reproduces. It also proves that evolution takes time--a fact that some people find difficult to accept.

Another example of microevolution is that mosquito genes that are resistant to pesticides show up more often in areas where insecticides are employed. Pesticides create an enticement that favors those with resistant genotypes.

The rapid pace of evolution taking place has led to a growing recognition of its importance in a world that is shaped by human activities, including climate change, pollution, and the loss of habitats that hinder many species from adapting. Understanding the evolution process can help us make better decisions about the future of our planet, as well as the life of its inhabitants.