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 who are interested in the sciences learn about the theory of evolution and how it is incorporated across all areas of scientific research.
This site provides students, teachers and general readers with a range of learning resources about evolution. It contains key video clips from NOVA and WGBH's 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, like providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
The first attempts to depict the world of biology were founded on categorizing organisms on their metabolic and physical characteristics. These methods, which are based on the collection of various parts of organisms or fragments of DNA have significantly increased the diversity of a Tree of Life2. These trees are largely composed by eukaryotes, and the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques enable us to create trees using sequenced markers such as the small subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However, there is still much biodiversity to be discovered. This is especially true for microorganisms that are difficult to cultivate and are typically found in a single specimen5. A recent analysis of all known genomes has produced a rough draft of the Tree of Life, including a large number of bacteria and archaea that are not isolated and their diversity is not fully understood6.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine whether specific habitats require protection. This information can be used in a range of ways, from identifying the most effective treatments to fight disease to enhancing the quality of crops. The information is also useful to conservation efforts. It can aid biologists in identifying areas that are most likely to be home to species that are cryptic, which could perform important metabolic functions and be vulnerable to changes caused by humans. While conservation funds are essential, the best way to conserve the world's biodiversity is to empower more people in developing nations with the knowledge they need to act locally and support conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between organisms. By using molecular information similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic groups. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that have evolved from common ancestors. These shared traits may be analogous, or homologous. Homologous traits are identical in their evolutionary roots, while analogous traits look similar but do not have the same origins. Scientists group similar traits into a grouping known as a clade. For instance, all of the species in a clade share the trait of having amniotic egg and evolved from a common ancestor who had eggs. The clades are then connected to create a phylogenetic tree to determine the organisms with the closest connection to each other.
For a more precise and accurate phylogenetic tree, scientists use molecular data from DNA or RNA to establish the relationships among organisms. This data is more precise than morphological data and provides evidence of the evolutionary history of an individual or group. Researchers can utilize Molecular Data to calculate the age of evolution 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 changes in response to unique environmental conditions. This can make a trait appear more similar to a species than to the other which can obscure the phylogenetic signal. However, this problem can be solved through the use of methods such as cladistics which include a mix of similar and homologous traits into the tree.
In addition, phylogenetics can help predict 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 that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms change over time due to their interactions with their environment. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would evolve according to its individual needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of traits can cause changes that can be passed on to future generations.
In the 1930s and 1940s, theories from a variety of fields -- including genetics, natural selection and particulate inheritance - came together to create the modern evolutionary theory which explains how evolution occurs through the variation of genes within a population and how those variants 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 the current evolutionary biology and can be mathematically explained.
Recent discoveries in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species by mutation, genetic drift and reshuffling of genes in sexual reproduction, and also through migration between populations. These processes, as well as other ones like directional selection and gene erosion (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time as well as changes in the phenotype (the expression of genotypes within individuals).
Students can gain a better understanding of phylogeny by incorporating evolutionary thinking in all aspects of biology. In a recent study conducted by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution boosted their understanding of evolution during a college-level course in biology. For more details on how to teach about evolution look up 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 traditionally looked at evolution through 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 happening right now. Bacteria transform and resist antibiotics, viruses re-invent themselves and elude new medications and animals change their behavior to a changing planet. The results are often visible.
It wasn't until late 1980s that biologists began realize that natural selection was at work. The key is that various characteristics result in different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.
In the past, if an allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could be more prevalent than any other allele. In time, this could mean that the number of moths sporting black pigmentation in a population may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
The ability to observe evolutionary change is much easier when a species has a fast generation turnover such as bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each are taken on a regular basis, and over fifty thousand generations have passed.
Lenski's research has revealed that mutations can alter the rate of change and the rate at which a population reproduces. It also shows that evolution takes time, a fact that is difficult for some to accept.
에볼루션 카지노 사이트 is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in populations that have used insecticides. Pesticides create an exclusive pressure that favors those who have resistant genotypes.
The speed of evolution taking place has led to an increasing awareness of its significance in a world that is shaped by human activities, including climate changes, pollution and the loss of habitats which prevent many species from adapting. Understanding evolution can help us make smarter choices about the future of our planet as well as the lives of its inhabitants.