14 Common Misconceptions About Evolution Site
The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those who are interested in science understand evolution theory and how it is incorporated throughout all fields of scientific research.
This site offers a variety of tools for teachers, students and general readers of 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 of the interconnectedness of all life. It is an emblem of love and harmony in a variety of cultures. It also has many practical uses, like providing a framework to understand the history of species and how they respond to changes in the environment.
The first attempts at depicting the world of biology focused on the classification of organisms into distinct categories which had been distinguished by physical and metabolic characteristics1. These methods are based on the sampling of different parts of organisms or DNA fragments, have greatly increased the diversity of a tree of Life2. However these trees are mainly made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular techniques 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 diversity to be discovered. This is particularly true for microorganisms, which are difficult to cultivate and are typically only found in a single sample5. A recent analysis of all genomes known to date has produced a rough draft of the Tree of Life, including numerous bacteria and archaea that have not been isolated and which are not well understood.
The expanded Tree of Life can be used to determine the diversity of a specific region and determine if certain habitats need special protection. This information can be utilized in a variety of ways, from identifying new treatments to fight disease to enhancing the quality of crop yields. This information is also extremely useful in conservation efforts. It helps biologists determine the areas most likely to contain cryptic species that could have important metabolic functions that may be vulnerable to anthropogenic change. Although funding to protect biodiversity are crucial but the most effective way to preserve the world's biodiversity is for more people living in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny (also known as an evolutionary tree) illustrates the relationship between species. Scientists can build a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and evolved from a common ancestor. These shared traits can be homologous, or analogous. Homologous traits are similar in their evolutionary roots while analogous traits appear similar but do not have the same ancestors. Scientists group similar traits into a grouping called a clade. All organisms in a group share a trait, such as amniotic egg production. They all derived from an ancestor that had these eggs. A phylogenetic tree is then constructed by connecting the clades to identify the species who are the closest to one another.
For a more detailed and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the relationships among organisms. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to determine the evolutionary age of organisms and determine how many species share the same ancestor.
The phylogenetic relationships between organisms are influenced by many factors, including phenotypic plasticity a kind of behavior that alters in response to specific environmental conditions. This can cause a characteristic to appear more similar in one species than another, clouding the phylogenetic signal. This issue can be cured by using cladistics. This is a method that incorporates the combination of homologous and analogous traits in the tree.
Additionally, phylogenetics can help predict the length and speed of speciation. This information can aid conservation biologists in making decisions about which species to safeguard from extinction. In the end, it's the preservation of phylogenetic diversity which will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme of evolution is that organisms acquire various characteristics over time due to their interactions with their environment. Many theories of evolution have been proposed by a wide variety of scientists including 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 the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that could be passed onto offspring.
In 에볼루션 and 1940s, ideas from different fields, including genetics, natural selection and particulate inheritance, came together to form a modern synthesis of evolution theory. This explains how evolution is triggered by the variation of genes in the population, and how these variations change with time due to natural selection. This model, which encompasses genetic drift, mutations as well as gene flow and sexual selection can be mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species through mutation, genetic drift, and reshuffling genes during sexual reproduction, and also through migration between populations. These processes, along with other ones like directional selection and gene erosion (changes in the frequency of genotypes over time), can lead towards 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 phylogeny by incorporating evolutionary thinking into all aspects of biology. In a study by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution boosted their understanding of evolution during the course of a college biology. For more details on how to teach evolution, see The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily: a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also observe living organisms. Evolution is not a distant event, but 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 alter their behavior in response to the changing environment. The resulting changes are often visible.
It wasn't until late 1980s that biologists understood that natural selection could be observed in action as well. The reason 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 when one particular allele--the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it might quickly become more prevalent than the other alleles. Over time, this would mean that the number of moths that have 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 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 500.000 generations have been observed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also shows evolution takes time, a fact that is hard for some to accept.
Another example of microevolution is the way mosquito genes for resistance to pesticides show up more often in areas where insecticides are employed. This is because the use of pesticides causes a selective pressure that favors individuals with resistant genotypes.
The speed at which evolution can take place has led to an increasing recognition of its importance in a world shaped by human activity, including climate change, pollution, and the loss of habitats that prevent many species from adapting. Understanding the evolution process will aid you in making better decisions about the future of the planet and its inhabitants.