14 Misconceptions Common To Evolution Site

The Academy's Evolution Site

Biological evolution is one of the most central concepts in biology. The Academies are committed to helping those who are interested in science comprehend the evolution theory and how it is permeated across all areas of scientific research.

This site provides a wide range of tools for students, teachers as well as general readers about evolution. It includes key video clips from NOVA and WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is a symbol of love and unity in many cultures. It has numerous practical applications as well, including providing a framework to understand the evolution of species and how they react to changing environmental conditions.

The first attempts to depict the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on sampling of different parts of living organisms or on sequences of short fragments of their DNA, significantly increased the variety that could be represented in a tree of life2. However the trees are mostly made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.

By avoiding the need for direct experimentation and observation genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. Trees can be constructed using molecular techniques like 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 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 the Tree of Life. This includes a variety of bacteria, archaea and other organisms that have not yet been isolated or the diversity of which is not fully understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine if specific habitats require special protection. This information can be utilized in a range of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of crops. It is also useful in 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 could be susceptible to human-induced change. While conservation funds are important, the most effective way to conserve the world's biodiversity is to equip more people in developing nations with the necessary knowledge to act locally and support conservation.

Phylogeny

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

A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms that have similar characteristics and have evolved from a common ancestor. These shared traits could be either homologous or analogous. Homologous traits are similar in their evolutionary origins and analogous traits appear similar but do not have the identical origins. Scientists arrange similar traits into a grouping called a clade. All members of a clade have a common characteristic, for example, amniotic egg production.  Suggested Studying  came from an ancestor that had these eggs. A phylogenetic tree is then constructed by connecting the clades to determine the organisms which are the closest to one another.

For a more detailed and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to establish the connections between organisms. This data is more precise than morphological information and provides evidence of the evolutionary history of an individual or group. The use of molecular data lets researchers identify the number of species that have a common ancestor and to estimate their evolutionary age.

Phylogenetic relationships can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is a kind of behavior that alters due to specific environmental conditions. This can cause a characteristic to appear more similar to one species than another, obscuring the phylogenetic signal. This problem can be addressed by using cladistics, which is a an amalgamation of homologous and analogous traits in the tree.

Additionally, phylogenetics can help predict the duration and rate of speciation. This information can help conservation biologists make decisions about which species they should protect from the threat of extinction. In the end, it's the conservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme in evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution have been proposed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop gradually according to its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that can be passed on to offspring.

In the 1930s and 1940s, ideas from different fields, such as genetics, natural selection, and particulate inheritance, were brought together to form a contemporary synthesis of evolution theory. This describes how evolution is triggered by the variation of genes in the population and how these variations change over time as a result of natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is a key element of modern evolutionary biology and is mathematically described.

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

Incorporating evolutionary thinking into all areas of biology education can increase student understanding of the concepts of phylogeny as well as evolution. In a recent study by Grunspan and co., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution in a college-level course in biology. For more information about how to teach evolution read The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Scientists have studied evolution through looking back in the past, studying 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 medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of the changing environment. The resulting changes are often easy to see.

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

In the past, when one particular allele - the genetic sequence that defines color in a population of interbreeding species, it could rapidly become more common than other alleles. In time, this could mean that the number of black moths in a particular population could rise. 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 the species, like bacteria, has a rapid generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each population are taken every day and over fifty thousand generations have been observed.

Lenski's research has demonstrated that mutations can alter the rate of change and the rate of a population's reproduction. It also shows that evolution takes time, something that is hard for some to accept.

Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides have been used. This is due to pesticides causing a selective pressure which favors those with resistant genotypes.

The rapidity of evolution has led to a growing appreciation of its importance especially in a planet that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution will assist you in making better choices about the future of our planet and its inhabitants.