The Academy's Evolution Site

Biology is one of the most fundamental concepts in biology. The Academies are involved in helping those interested in science to understand evolution theory and how it is permeated throughout all fields of scientific research.

This site provides students, teachers and general readers with a range of learning resources about evolution. It has the most important video clips from NOVA and 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 harmony in a variety of cultures. It also has practical uses, like providing a framework for understanding the evolution of species and how they respond to changes in environmental conditions.

Early attempts to describe the world of biology were based on categorizing organisms based on their metabolic and physical characteristics. These methods, which relied on the sampling of different parts of living organisms or sequences of short fragments of their DNA greatly increased the variety of organisms that could be represented in a tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.

Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the need for direct observation and 에볼루션 블랙잭 게이밍 (Rodriguez-Jones-2.Technetbloggers.De) experimentation. We can construct trees using molecular techniques such as the small subunit ribosomal gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However there is a lot of diversity to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are often only represented in a single sample5. A recent analysis of all genomes known to date has produced a rough draft version of the Tree of Life, including numerous bacteria and archaea that have not been isolated, and whose diversity is poorly understood6.

This expanded Tree of Life can be used to determine the diversity of a particular area and determine if particular habitats require special protection. The information is useful in a variety of ways, such as finding new drugs, battling diseases and improving crops. The information is also incredibly beneficial to conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species with potentially important metabolic functions that may be vulnerable to anthropogenic change. Although funding to protect biodiversity are essential however, the most effective method to ensure the preservation of biodiversity around the world is for more people living in developing countries to be empowered with the knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, reveals the connections between groups of organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic groups using molecular data and morphological differences or similarities. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics.

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 could be analogous or homologous. Homologous traits are the same in terms of their evolutionary journey. Analogous traits may look similar however they do not share the same origins. Scientists combine similar traits into a grouping known as a the clade. Every organism in a group have a common trait, such as amniotic egg production. They all derived from an ancestor with these eggs. The clades are then connected to form a phylogenetic branch to determine the organisms with the closest connection to each other.

Scientists use DNA or RNA molecular information to construct a phylogenetic graph that is more accurate and detailed. This information is more precise than morphological information and gives evidence of the evolutionary history of an organism or 무료 에볼루션 group. The use of molecular data lets researchers determine the number of organisms who share a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships between species can be affected by a variety of factors, including phenotypic flexibility, a type of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more resembling to one species than to another and obscure the phylogenetic signals. This problem can be addressed by using cladistics, which is a the combination of analogous and homologous features in the tree.

Furthermore, phylogenetics may help predict the length and speed of speciation. This information can aid conservation biologists in making decisions about which species to protect from extinction. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme in evolution is that organisms change over time as a result 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 evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of certain traits can result in changes that are passed on to the

In the 1930s and 1940s, ideas from different fields, such as genetics, natural selection, and particulate inheritance, merged to create a modern theorizing of evolution. This defines how evolution occurs by the variation of genes in a population and how these variants alter over time due to natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically explained.

Recent developments in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species by mutation, genetic drift and reshuffling of genes in sexual reproduction, 에볼루션게이밍 (intern.Ee.aeust.Edu.Tw) and also by migration between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time), can lead to evolution that is defined as changes in the genome of the species over time and also the change in phenotype as time passes (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 demonstrated that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college biology course. For more details about how to teach evolution, see The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily A Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by looking back--analyzing fossils, comparing species, and studying living organisms. Evolution is not a past event, but an ongoing process. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior because of the changing environment. The changes that result are often apparent.

However, it wasn't until late-1980s that biologists realized that natural selection could be observed in action as well. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and are passed from one generation to the next.

In the past, if an allele - the genetic sequence that determines colour appeared in a population of organisms that interbred, it might become more common than other allele. In time, this could mean that the number of moths that have black pigmentation 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 an organism, like bacteria, has a high generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples of each population are taken on a regular basis and more than 50,000 generations have now been observed.

Lenski's research has revealed that mutations can alter the rate at which change occurs and the efficiency of a population's reproduction. 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 resistance to pesticides are more prevalent in populations where insecticides have been used. Pesticides create a selective pressure which favors individuals who have resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance, especially in a world which is largely shaped by human activities. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding evolution can help us make better decisions regarding the future of our planet as well as the lives of its inhabitants.