The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those interested in science to understand evolution theory and how it can be applied in all areas of scientific research.

This site offers a variety of tools for students, teachers as well as general readers about evolution. It includes the most important video clips from NOVA and WGBH's science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is a symbol of love and unity in many cultures. It also has practical applications, such as providing a framework to understand the history of species and how they react to changes in environmental conditions.

Early approaches to depicting the world of biology focused on separating species into distinct categories that were distinguished by physical and metabolic characteristics1. These methods rely on the sampling of different parts of organisms or DNA fragments, have significantly increased the diversity of a tree of Life2. However, these trees are largely comprised of eukaryotes, and 에볼루션 bacterial diversity is not represented in a large way3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have allowed us to depict the Tree of Life in a more precise manner. Particularly, molecular methods enable us to create trees by using sequenced markers like the small subunit of ribosomal RNA gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly true for microorganisms, which can be difficult to cultivate and are often only represented in a single specimen5. A recent study of all known genomes has created a rough draft of the Tree of Life, including many bacteria and archaea that are not isolated and whose diversity is poorly understood6.

The expanded Tree of Life can be used to determine the diversity of a particular area and determine if certain habitats need special protection. The information is useful in a variety of ways, including finding new drugs, fighting diseases and improving crops. The information is also valuable in conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which may perform important metabolic functions and be vulnerable to the effects of human activity. While conservation funds are essential, the best way to conserve the world's biodiversity is to empower more people in developing nations with the knowledge they need to act locally and support conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between organisms. Scientists can construct a phylogenetic chart that shows the evolutionary relationships between taxonomic categories using molecular information and morphological similarities or differences. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and have evolved from an ancestor that shared traits. These shared traits could be either analogous or homologous. Homologous characteristics are identical in their evolutionary path. Analogous traits might appear like they are however they do not share the same origins. Scientists put similar traits into a grouping called a the clade. For instance, all of the species in a clade have the characteristic of having amniotic eggs and evolved from a common ancestor which had these eggs. A phylogenetic tree can be constructed by connecting the clades to identify the species that are most closely related to each other.

Scientists use molecular DNA or RNA data to build a phylogenetic chart that is more accurate and precise. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to estimate the age of evolution of organisms and determine the number of organisms that share a common ancestor.

The phylogenetic relationships between organisms can be affected by a variety of factors, including phenotypic flexibility, an aspect of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more similar to one species than another, clouding the phylogenetic signal. However, this problem can be solved through the use of techniques such as cladistics which include a mix of similar and homologous traits into the tree.

Additionally, phylogenetics aids determine the duration and rate at which speciation takes place. This information will assist conservation biologists in deciding which species to safeguard from extinction. In the end, it's the preservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms develop different features over time due to their interactions with their environments. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can cause changes that can be passed on to future generations.

In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance--came together to create the modern synthesis of evolutionary theory that explains how evolution is triggered by the variations of genes within a population, and how those variations change over time due to natural selection. This model, called genetic drift, 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 shown how variations can be introduced to a species through genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as others such as directional selection and gene erosion (changes in the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time and changes in the phenotype (the expression of genotypes within individuals).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all aspects of biology. A recent study conducted by Grunspan and colleagues, for example, showed that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology course. For more information on how to teach about evolution, see The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally looked at evolution through the past--analyzing fossils and comparing species. They also study living organisms. But evolution isn't a thing that happened in the past; it's an ongoing process, that is taking place today. Bacteria mutate and 에볼루션 무료 바카라 resist antibiotics, viruses evolve and elude new medications, and animals adapt their behavior in response to the changing climate. The results are often visible.

It wasn't until late 1980s that biologists understood that natural selection could be seen in action, as well. The key is that different traits have different rates of survival and reproduction (differential fitness), and can be passed from one generation to the next.

In the past, if a certain allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could become more common than any other allele. Over time, that would mean that the number of black moths 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 evolution when a species, 에볼루션 게이밍 에볼루션 바카라 무료 바카라 에볼루션 (how you can help) such as bacteria, has a high generation turnover. Since 1988 the 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 over fifty thousand generations have been observed.

Lenski's research has shown that a mutation can dramatically alter the speed at the rate at which a population reproduces, and consequently the rate at which it alters. It also shows that evolution takes time, a fact that is difficult for some to accept.

Another example of microevolution is how mosquito genes for resistance to pesticides show up more often in populations where insecticides are employed. Pesticides create an enticement that favors individuals who have resistant genotypes.

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