The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies have long been involved in helping people who are interested in science comprehend the concept of evolution and how it permeates every area of scientific inquiry.

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

Tree of Life

The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It appears in many spiritual traditions and cultures as symbolizing unity and love. It can be used in many practical ways in addition to providing a framework to understand the history of species, and how they respond to changing environmental conditions.

Early attempts to represent the biological world were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which rely on sampling of different parts of living organisms, or sequences of short DNA fragments, significantly increased the variety that could be represented in the tree of life2. These trees are largely composed of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have enabled us to depict the Tree of Life in a more precise way. Trees can be constructed by using molecular methods such as the small subunit ribosomal gene.

Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is particularly true of microorganisms, which are difficult to cultivate and are typically only represented in a single sample5. Recent analysis of all genomes resulted in an initial draft of a Tree of Life. This includes a variety of archaea, bacteria, and other organisms that haven't yet been isolated or their diversity is not thoroughly understood6.

The expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if specific habitats require special protection. This information can be utilized in a variety of ways, such as finding new drugs, 에볼루션 게이밍 fighting diseases and improving crops. This information is also useful in conservation efforts. It can help biologists identify areas that are likely to be home to species that are cryptic, 에볼루션 바카라 which could have important metabolic functions, and could be susceptible to changes caused by humans. While funds to protect biodiversity are important, the best method to preserve the biodiversity of the world is to equip more people in developing nations with the information they require to act locally and promote conservation.

Phylogeny

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

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestral. These shared traits are either homologous or analogous. Homologous traits share their evolutionary roots, while analogous traits look similar, but do not share the same ancestors. Scientists arrange similar traits into a grouping known as a clade. Every organism in a group share a characteristic, for 에볼루션 무료체험 example, amniotic egg production. They all came from an ancestor with these eggs. The clades then join to form a phylogenetic branch to determine which organisms have the closest connection to each other.

Scientists utilize DNA or RNA molecular data to create a phylogenetic chart that is more accurate and precise. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can use Molecular Data to calculate the age of evolution of organisms and identify how many species share the same ancestor.

The phylogenetic relationships between organisms are influenced by many factors including phenotypic plasticity, a type of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar in one species than another, clouding the phylogenetic signal. However, this problem can be solved through the use of methods such as cladistics which incorporate a combination of homologous and analogous features into the tree.

Additionally, phylogenetics aids predict the duration and rate at which speciation occurs. This information will assist conservation biologists in deciding which species to save from disappearance. In the end, it's the conservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept in evolution is that organisms change over time as a result of their interactions with their environment. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would develop according to its own needs, 에볼루션 게이밍 the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can cause changes that can be passed on to future generations.

In the 1930s & 1940s, theories from various fields, including natural selection, genetics & particulate inheritance, were brought together to form a contemporary synthesis of evolution theory. This explains how evolution is triggered by the variations in genes within the population, and how these variations change over time as a result of natural selection. This model, known as genetic drift or 무료에볼루션 mutation, gene flow, and sexual selection, is the foundation of current evolutionary biology, and can be mathematically described.

Recent developments in the field of evolutionary developmental biology have revealed that variation can be introduced into a species via mutation, genetic drift and reshuffling of genes during sexual reproduction, as well as through migration between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can result in evolution, which is defined by changes in the genome of the species over time, and also by changes in phenotype over time (the expression of that genotype in an individual).

Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college-level biology course. For more information on how to teach about 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

Scientists have looked at evolution through the past--analyzing fossils and comparing species. They also study living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process that is taking place in the present. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior because of a changing world. The resulting changes are often visible.

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

In the past, if a certain allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could be more prevalent than any other allele. In time, this could mean that the number of moths that have 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 see evolutionary change when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. The samples of each population have been taken regularly, and more than 50,000 generations of E.coli have passed.

Lenski's research has revealed that mutations can drastically alter the rate at which a population reproduces and, consequently the rate at which it alters. It also proves that evolution is slow-moving, a fact that some people are unable to accept.

Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas that have used insecticides. That's because the use of pesticides creates a selective pressure that favors people who have resistant genotypes.

The rapidity of evolution has led to a greater recognition of its importance particularly in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution can assist you in making better choices about the future of our planet and its inhabitants.