The Academy's Evolution Site

Biological evolution is one of the most important concepts in biology. The Academies have long been involved in helping people who are interested in science understand the theory of evolution and how it permeates every area of scientific inquiry.

This site provides students, teachers and general readers with a range of learning resources on evolution. It also includes important 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 all life. It is an emblem of love and unity across many cultures. It also has practical uses, like providing a framework to understand the evolution of species and how they respond to changes in the environment.

Early approaches to depicting the world of biology focused on separating organisms into distinct categories which were distinguished by their physical and metabolic characteristics1. These methods are based on the collection of various parts of organisms, or DNA fragments, have significantly increased the diversity of a tree of Life2. The trees are mostly composed by eukaryotes and bacteria are largely underrepresented3,4.

Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. We can construct trees by using molecular methods like the small-subunit ribosomal gene.

Despite the massive growth of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is especially relevant to microorganisms that are difficult to cultivate, 에볼루션바카라사이트 and are typically present in a single sample5. Recent analysis of all genomes resulted in an unfinished draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that have not yet been identified or the diversity of which is not fully understood6.

This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if specific habitats require special protection. This information can be used in many ways, including finding new drugs, battling diseases and enhancing crops. The information is also beneficial in conservation efforts. It helps biologists discover areas most likely to be home to cryptic species, which could have vital metabolic functions, and could be susceptible to the effects of human activity. While conservation funds are important, the best method to preserve the world's biodiversity is to empower more people in developing countries with the information they require to act locally and promote conservation.

Phylogeny

A phylogeny, also called an evolutionary tree, reveals the connections between groups of organisms. Using molecular data as well as morphological similarities and distinctions, or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree which illustrates the evolution of taxonomic categories. Phylogeny is crucial in understanding evolution, biodiversity and genetics.

A basic phylogo an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their surroundings. A variety of theories about evolution have been developed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that could be passed onto offspring.

In the 1930s & 1940s, theories from various fields, such as natural selection, genetics & particulate inheritance, merged to form a modern theorizing of evolution. This explains how evolution occurs by the variation in genes within the population and how these variations change with time due to natural selection. This model, 에볼루션 바카라 무료 which is known as genetic drift or 에볼루션바카라사이트 mutation, gene flow and sexual selection, is a cornerstone of current evolutionary biology, and can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have revealed how variations can be introduced to a species via genetic drift, mutations or reshuffling of genes in sexual reproduction, and 에볼루션바카라사이트 even migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time) can lead to evolution, which is defined by changes in the genome of the species over time and also by changes in phenotype as time passes (the expression of the genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny and evolutionary. A recent study by Grunspan and colleagues, for instance, showed that teaching about the evidence for evolution increased students' understanding of evolution in a college-level biology course. To learn more about how to teach about evolution, see The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution by studying fossils, comparing species, and studying living organisms. Evolution isn't a flims event, but an ongoing process that continues to be observed today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of a changing world. The results are usually visible.

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

In the past, when 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. In time, this could mean that the number of moths sporting black pigmentation in 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 track evolutionary change when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from one strain. Samples of each population have been taken regularly, and more than 500.000 generations of E.coli have passed.

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

Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more common in populations that have used insecticides. This is because pesticides cause a selective pressure which favors those with resistant genotypes.

The rapid pace at which evolution takes place has led to an increasing appreciation of its importance in a world that is shaped by human activities, including climate change, pollution and the loss of habitats that prevent many species from adapting. Understanding evolution can help us make smarter decisions about the future of our planet, and the lives of its inhabitants.