The Academy's Evolution Site
Biological evolution is one of the most central 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 permeates all areas of scientific exploration.
This site provides students, teachers and general readers with a range of learning resources on evolution. It contains key video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that represents the interconnectedness of all life. It is seen in a variety of cultures and spiritual beliefs as a symbol of unity and love. It also has practical applications, such as providing a framework for understanding the history of species and how they react to changes in environmental conditions.
Early approaches to depicting the biological world focused on separating organisms into distinct categories which were distinguished by their physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of living organisms, or sequences of short fragments of their DNA significantly increased the variety that could be included in the tree of life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4.
By avoiding the necessity for direct observation and experimentation genetic techniques have enabled us to represent the Tree of Life in a more precise way. We can construct trees using molecular methods, such as the small-subunit ribosomal gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is especially relevant to microorganisms that are difficult to cultivate and are usually found in one sample5. A recent analysis of all genomes known to date has created a rough draft of the Tree of Life, including numerous bacteria and archaea that have not been isolated and their diversity is not fully understood6.
This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine whether specific habitats require special protection. The information is useful in a variety of ways, including finding new drugs, fighting diseases and improving the quality of crops. The information is also valuable to conservation efforts. It can aid biologists in identifying areas most likely to be home to cryptic species, which may have vital metabolic functions and be vulnerable to human-induced change. Although funds to protect biodiversity are crucial, 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 is also known as an evolutionary tree, shows the relationships between groups of organisms. Utilizing molecular data as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree that illustrates the evolutionary relationships between taxonomic categories. The role of phylogeny is crucial in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from a common ancestor. These shared traits are either analogous or homologous. Homologous traits are identical in their underlying evolutionary path, while analogous traits look similar but do not have the same origins. Scientists organize similar traits into a grouping known as a the clade. All organisms in a group have a common trait, such as amniotic egg production. They all evolved from an ancestor that had these eggs. The clades are then connected to form a phylogenetic branch that can identify organisms that have the closest relationship to.
Scientists use DNA or RNA molecular data to build a phylogenetic chart that is more precise and precise. This information is more precise than morphological information and provides evidence of the evolution history of an organism or group. Researchers can use Molecular Data to calculate the age of evolution of organisms and determine the number of organisms that share an ancestor common to all.
The phylogenetic relationships of a species can be affected by a variety of factors that include phenotypicplasticity. This is a type of behavior that alters due to particular environmental conditions. This can cause a trait to appear more resembling to one species than to another which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics, which incorporates a combination of analogous and homologous features in the tree.
Furthermore, phylogenetics may aid in predicting the time and pace of speciation. This information can assist conservation biologists make decisions about which species they should protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will create a complete and balanced ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms acquire different features over time based on 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 would evolve according to its individual requirements as well as 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 suggested that the use or non-use of certain traits can result in 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 form the current evolutionary theory that explains how evolution is triggered by the variation of genes within a population and how these variants change over time as a result of natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is the foundation of the current evolutionary biology and is mathematically described.
Recent developments in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species via 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 genetic erosion (changes in the frequency of an individual's genotype over time) can lead to evolution that is defined as 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).
Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny and evolution. A recent study by Grunspan and colleagues, for instance, showed that teaching about the evidence for evolution increased students' acceptance of evolution in a college-level biology course. To learn more about how to teach about evolution, please look up The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through studying fossils, comparing species and observing living organisms. But evolution isn't a thing that occurred in the past. It's an ongoing process happening today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior in the wake of a changing environment. The resulting changes are often visible.
But it wasn't until the late-1980s that biologists realized that natural selection could be observed in action as well. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.
In the past, if one particular allele--the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it could quickly become more common than other alleles. In time, this could mean that 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.
The ability to observe evolutionary change is much easier when a species has a fast generation turnover like bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples of each are taken regularly and more than fifty thousand generations have passed.
Lenski's research has revealed that mutations can drastically alter the speed at which a population reproduces and, consequently, the rate at which it alters. mouse click the up coming internet site shows that evolution takes time, a fact that some people find difficult to accept.
Another example of microevolution is the way mosquito genes that are resistant to pesticides appear more frequently in areas where insecticides are employed. Pesticides create an enticement that favors those with resistant genotypes.
The speed of evolution taking place has led to an increasing appreciation of its importance in a world shaped by human activity, including climate change, pollution and the loss of habitats which prevent the species from adapting. Understanding the evolution process can help us make better decisions about the future of our planet, and the life of its inhabitants.