The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies have been for a long time involved in helping those interested in science comprehend the concept of evolution and how it affects every area of scientific inquiry.

This site provides a range of resources for teachers, students, and general readers on evolution. It also includes 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 unity in many cultures. It has many practical applications in addition to 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 categorizing organisms into distinct categories which had been distinguished by physical and 에볼루션 바카라 무료체험 (Gratisafhalen.Be) metabolic characteristics1. These methods, 에볼루션 슬롯게임 which relied on the sampling of different parts of living organisms or on short fragments of their DNA, 에볼루션 사이트 greatly increased the variety of organisms that could be included in the tree of life2. The trees are mostly composed of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.

In avoiding the necessity of direct observation and experimentation, genetic techniques have enabled us to depict the Tree of Life in a more precise way. In particular, 에볼루션바카라 molecular methods allow us to construct trees by using sequenced markers, such as the small subunit of ribosomal RNA gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of biodiversity to be discovered. This is especially true for microorganisms that are difficult to cultivate and are usually found in a single specimen5. A recent analysis of all genomes resulted in an unfinished draft of a Tree of Life. This includes a wide range of bacteria, archaea and other organisms that have not yet been isolated, or their diversity is not well understood6.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine whether specific habitats require protection. This information can be used in a variety of ways, such as finding new drugs, battling diseases and improving the quality of crops. This information is also extremely beneficial to conservation efforts. It can help biologists identify areas that are most likely to be home to cryptic species, which may have important metabolic functions and be vulnerable to changes caused by humans. Although funds to safeguard biodiversity are vital, ultimately the best way to preserve the world's biodiversity is for more people living in developing countries to be empowered with the necessary knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny is also known as an evolutionary tree, shows the relationships between different groups of organisms. Scientists can build an phylogenetic chart which shows the evolution of taxonomic categories using molecular information and morphological differences or similarities. The concept of phylogeny is fundamental to understanding evolution, biodiversity and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms with similar characteristics and have evolved from an ancestor that shared traits. These shared traits can be either homologous or analogous. Homologous traits are similar in their evolutionary journey. Analogous traits may look like they are however they do not have the same origins. Scientists group similar traits into a grouping known as a the clade. For instance, all of the organisms in a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor who had these eggs. The clades are then connected to form a phylogenetic branch to determine the organisms with the closest relationship.

Scientists make use of DNA or RNA molecular data to create a phylogenetic chart that is more precise and detailed. This data is more precise than morphological data and provides evidence of the evolution background of an organism or group. Researchers can use Molecular Data to estimate the evolutionary age of organisms and identify how many organisms have an ancestor common to all.

The phylogenetic relationships of a species can be affected by a variety of factors that include the phenotypic plasticity. This is a kind of behavior that alters as a result of unique environmental conditions. This can cause a particular trait to appear more like a species another, obscuring the phylogenetic signal. However, this problem can be reduced by the use of techniques like cladistics, which combine homologous and analogous features into the tree.

Additionally, phylogenetics can help predict the time and pace of speciation. This information can assist conservation biologists decide the species they should safeguard from extinction. In the end, it's the preservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.

Evolutionary Theory

The main idea behind evolution is that organisms acquire various characteristics over time as a result of their interactions with their surroundings. A variety of theories about evolution have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that can be passed on to offspring.

In the 1930s and 1940s, 에볼루션카지노 ideas from various fields, including natural selection, genetics, and particulate inheritance--came together to form the current evolutionary theory synthesis which explains how evolution is triggered by the variations of genes within a population and how those variants change in time due to natural selection. This model, which is known as genetic drift or mutation, gene flow, and sexual selection, is the foundation of the current evolutionary biology and is mathematically described.

Recent developments in evolutionary developmental biology have revealed the ways in which variation can be introduced to a species by genetic drift, mutations and reshuffling of genes during sexual reproduction and migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of the 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 over time (the expression of that genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny as well as evolution. A recent study conducted by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. For more information on how to teach about evolution, read The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution by looking in the past--analyzing fossils and comparing species. They also observe 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. Viruses reinvent themselves to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior in the wake of the changing environment. The results are often evident.

It wasn't until late 1980s when biologists began to realize that natural selection was also in action. The key to this is that different traits confer an individual rate of survival as well as reproduction, and may be passed on from one generation to the next.

In the past, if an allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could become more common than any other allele. In time, this could mean the number of black moths within the 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, 에볼루션 사이트 has a rapid 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 에볼루션 사이트 more than 500.000 generations have passed.

Lenski's work has shown that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows 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 prevalent in populations where insecticides are used. This is due to pesticides causing an exclusive pressure that favors those who have resistant genotypes.

The rapidity of evolution has led to a growing recognition of its importance particularly in a world which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution will aid you in making better decisions about the future of our planet and its inhabitants.