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3 Reasons You're Evolution Site Is Broken (And How To Fix It)
The Academy's Evolution Site

The concept of biological evolution is among the most important concepts in biology. The Academies are committed to helping those interested in the sciences comprehend the evolution theory and how it can be applied throughout all fields of scientific research.

This site provides teachers, students and general readers with a variety of learning resources about evolution. It has key video clips from NOVA and the WGBH-produced science programs on DVD.

Tree of Life

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

The first attempts to depict the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, based on the sampling of different parts of living organisms, or small fragments of their DNA, significantly expanded the diversity that could be included in a tree of life2. However, these trees are largely comprised of eukaryotes, and bacterial diversity is not represented in a large way3,4.

Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. We can construct trees using molecular methods, 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 biodiversity to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are typically only represented in a single specimen5. Recent analysis of all genomes resulted in a rough draft of the Tree of Life. This includes a large number of bacteria, archaea and other organisms that haven't 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, which can help to determine if certain habitats require special protection. This information can be utilized in a range of ways, from identifying the most effective medicines to combating disease to improving crops. It is also valuable for conservation efforts. It can aid biologists in identifying areas that are likely to have cryptic species, which could have vital metabolic functions, and could be susceptible to the effects of human activity. Although funding to safeguard biodiversity are vital 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 necessary knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, shows the connections between different groups of organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic groups using molecular data and morphological similarities or differences. Phylogeny is crucial in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and have evolved from a common ancestor. These shared traits can be either analogous or homologous. My Source are the same in their evolutionary paths. Analogous traits might appear similar however they do not share the same origins. Scientists combine similar traits into a grouping called a clade. All organisms in a group have a common characteristic, for example, amniotic egg production. They all evolved from an ancestor that had these eggs. The clades are then linked to form a phylogenetic branch to determine the organisms with the closest relationship to.


Scientists use DNA or RNA molecular information to build a phylogenetic chart which is more precise and detailed. This information is more precise and provides evidence of the evolution history of an organism. Molecular data allows researchers to determine the number of species who share the same ancestor and estimate their evolutionary age.

Phylogenetic relationships can be affected by a number of factors that include the phenomenon of phenotypicplasticity. This is a type of behaviour that can change in response to unique environmental conditions. This can cause a particular trait to appear more similar in one species than another, clouding the phylogenetic signal. However, this issue can be cured by the use of techniques such as cladistics that include a mix of homologous and analogous features into the tree.

In addition, phylogenetics helps determine the duration and speed of speciation. This information can aid conservation biologists in deciding which species to safeguard from extinction. In the end, it is the conservation of phylogenetic variety that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire distinct characteristics over time as a result of their interactions with their environments. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could develop according to its own needs as well as 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 usage or non-use of traits can cause changes that can be passed on to future generations.

In the 1930s and 1940s, ideas from a variety of fields--including natural selection, genetics, and particulate inheritance -- came together to form the current evolutionary theory synthesis which explains how evolution happens through the variation of genes within a population and how those variations change in time as a result of natural selection. This model, which is known as genetic drift or mutation, gene flow and sexual selection, is a key element of modern evolutionary biology and can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have revealed that variations can be introduced into a species through mutation, genetic drift and reshuffling of genes in sexual reproduction, as well as through migration between populations. These processes, as well as 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 as time passes (the expression of the genotype in the individual).

Students can better understand phylogeny by incorporating evolutionary thinking in all areas of biology. In a study by Grunspan et al., it was shown that teaching students about the evidence for evolution increased their understanding of evolution in an undergraduate biology course. To find out more about how to teach about evolution, see The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution through looking back in the past, studying fossils, and comparing species. They also observe living organisms. Evolution is not a distant moment; it is an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals change their behavior in response to the changing environment. The results are usually easy to see.

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

In the past, if an allele - the genetic sequence that determines colour - was found in a group of organisms that interbred, it could be more common than other allele. Over time, that would mean the number of black moths in the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Monitoring evolutionary changes in action is easier when a species has a rapid turnover of its generation like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. Samples of each population have been taken regularly and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's research has demonstrated that mutations can alter the rate of change and the rate of a population's reproduction. It also demonstrates that evolution takes time--a fact that some are unable to accept.

Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more common in populations that have used insecticides. This is because pesticides cause an exclusive pressure that favors those who have resistant genotypes.

The speed at which evolution can take place has led to an increasing recognition of its importance in a world that is shaped by human activities, including climate changes, pollution and the loss of habitats that hinder many species from adapting. Understanding evolution can aid you in making better decisions about the future of our planet and its inhabitants.