The Academy's Evolution Site

Biology is one of the most important concepts in biology. The Academies have been for a long time involved in helping those interested in science understand the concept of evolution and how it influences all areas of scientific research.

This site provides a range of sources for teachers, students and general readers of evolution. It contains 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 across many cultures. It also has practical applications, such as providing a framework for understanding the history of species and how they react to changes in the environment.

The first attempts to depict the biological world were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which rely on the sampling of various parts of living organisms or small fragments of their DNA greatly increased the variety of organisms that could be represented in the tree of life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4.

Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular methods such as the small subunit ribosomal gene.

The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly true for microorganisms, which are difficult to cultivate and are often only present in a single sample5. A recent analysis of all known genomes has created a rough draft of the Tree of Life, including numerous bacteria and archaea that are not isolated and which are not well understood.

This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine if certain habitats require protection. This information can be utilized in a range of ways, from identifying new treatments to fight disease to enhancing crops. This information is also beneficial in conservation efforts. It helps biologists discover areas most likely to be home to cryptic species, which could have vital metabolic functions and are susceptible to human-induced change. Although funding to protect biodiversity are essential, ultimately the best way to protect the world's biodiversity 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 known as an evolutionary tree, illustrates the relationships between different groups of organisms. By using molecular information similarities and differences in morphology or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolution of taxonomic categories. The phylogeny of a tree plays an important role in understanding genetics, biodiversity and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits may be analogous or homologous. Homologous traits are identical in their underlying evolutionary path, while analogous traits look like they do, but don't have the same origins. Scientists organize similar traits into a grouping called a clade. For instance, all the organisms that make up a clade have the characteristic of having amniotic egg and evolved from a common ancestor who had these eggs. The clades are then connected to form a phylogenetic branch that can determine which organisms have the closest relationship.

For a more precise and accurate phylogenetic tree, scientists use molecular data from DNA or RNA to identify the relationships among organisms. This information is more precise and gives evidence of the evolution history of an organism. Researchers can use Molecular Data to determine the age of evolution of living organisms and discover how many species have a common ancestor.

The phylogenetic relationship can be affected by a variety of factors such as the phenomenon of phenotypicplasticity. This is a type behavior that changes as a result of unique environmental conditions. This can cause a trait to appear more resembling to one species than to the other, obscuring the phylogenetic signals. This issue can be cured by using cladistics. This is a method that incorporates a combination of analogous and homologous features in the tree.

In addition, phylogenetics can aid in predicting the time and pace of speciation. This information can assist conservation biologists in making decisions about which species to safeguard from disappearance. In the end, it's the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms alter over time because of their interactions with their environment. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can cause changes that are passed on to the


In the 1930s and 1940s, concepts from various fields, including natural selection, genetics, and particulate inheritance -- came together to create the modern evolutionary theory which explains how evolution is triggered by the variations of genes within a population, and how those variations change over time as a result of natural selection. This model, which incorporates mutations, genetic drift in gene flow, and sexual selection is mathematically described mathematically.

Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species by genetic drift, mutation, and reshuffling of genes in sexual reproduction, as well as through the movement of populations. These processes, in conjunction with others, such as directionally-selected selection and erosion of genes (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time, as well as changes in phenotype (the expression of genotypes within individuals).

Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking in all aspects of biology. In a recent study by Grunspan et al., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution in the course of a college biology. For more details about how to teach evolution read The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily: a Framework for Infusing 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 study living organisms. Evolution is not a distant event; it is a process that continues today. Bacteria evolve and resist antibiotics, viruses reinvent themselves and elude new medications and animals alter their behavior to the changing environment. The changes that occur are often evident.

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

In the past, if one allele - the genetic sequence that determines colour was present 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 sporting black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to track evolution when an organism, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. Samples of each population were taken regularly, and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's work has demonstrated that a mutation can profoundly alter the efficiency with which a population reproduces--and so, the rate at which it alters. It also demonstrates that evolution takes time--a fact that some people find hard to accept.

Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more common in populations where insecticides are used. 에볼루션 코리아 's because the use of pesticides creates a selective pressure that favors individuals who have resistant genotypes.

The speed of evolution taking place has led to an increasing appreciation of its importance in a world that is shaped by human activity--including climate changes, pollution and the loss of habitats that hinder many species from adapting. Understanding the evolution process will aid you in making better decisions about the future of our planet and its inhabitants.