The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have long been involved in helping those interested in science comprehend the concept of evolution and how it affects all areas of scientific exploration.
This site provides students, teachers and general readers with a range of learning resources on evolution. It has important video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of all life. It is seen in a variety of cultures and spiritual beliefs as a symbol of unity and love. It has many practical applications as well, such as providing a framework for understanding the history of species, and how they respond to changing environmental conditions.
Early attempts to describe the biological world were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which relied on the sampling of various parts of living organisms or small DNA fragments, significantly increased the variety that could be included in a tree of life2. These trees are mostly populated of eukaryotes, while bacteria are largely underrepresented3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. We can create trees using molecular techniques, such as the small-subunit ribosomal gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is particularly the case for microorganisms which are difficult to cultivate, and which are usually only present in a single sample5. A recent study of all genomes known to date has produced a rough draft of the Tree of Life, including many archaea and bacteria 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, which can help to determine if specific habitats require 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. The information is also useful in conservation efforts. It can help biologists identify those areas that are most likely contain cryptic species with significant metabolic functions that could be vulnerable to anthropogenic change. While conservation funds are important, the best way to conserve the biodiversity of the world is to equip more people in developing nations with the information they require to act locally and promote conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, shows the relationships between various groups of organisms. Utilizing molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism), scientists can build an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic groups. Phylogeny is crucial in understanding biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestors. These shared traits can be analogous, or homologous. Homologous traits share their evolutionary origins, while analogous traits look like they do, but don't have the same origins. Scientists combine similar traits into a grouping referred to as a clade. For instance, all of the organisms in a clade share the trait of having amniotic eggs and evolved from a common ancestor that had eggs. The clades are then linked to form a phylogenetic branch to determine the organisms with the closest relationship to.
To create 에볼루션카지노 and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the relationships between organisms. This data is more precise than morphological data and gives evidence of the evolutionary history of an individual or group. Molecular data allows researchers to determine the number of species that have a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships of a species can be affected by a number of factors such as the phenomenon of phenotypicplasticity. This is a type of behaviour that can change in response to specific environmental conditions. This can cause a trait to appear more resembling to one species than to another and obscure the phylogenetic signals. This issue can be cured by using cladistics. This is a method that incorporates an amalgamation of analogous and homologous features in the tree.
Additionally, phylogenetics aids predict the duration and rate at which speciation takes place. This information can aid conservation biologists in deciding which species to save from disappearance. In the end, it is the conservation of phylogenetic variety that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms develop distinct characteristics over time due to their interactions with their environment. Several theories of evolutionary change have been developed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that could be passed onto offspring.
In the 1930s & 1940s, theories from various areas, including natural selection, genetics & particulate inheritance, came together to create a modern theorizing of evolution. This describes how evolution happens through the variation in genes within a population and how these variants alter over time due to natural selection. This model, known as genetic drift, mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and is mathematically described.
Recent advances in evolutionary developmental biology have revealed how variation can be introduced to a species via mutations, genetic drift, reshuffling genes during sexual reproduction, and even migration between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can lead to evolution, which is defined by change in the genome of the species over time and also the change in phenotype as time passes (the expression of that genotype within the individual).
Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all areas of biology. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence for evolution increased students' understanding of evolution in a college-level biology course. To find out more about how to teach about evolution, look up The Evolutionary Potential of 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 by studying fossils, comparing species, and studying living organisms. But evolution isn't a thing that happened in the past, it's an ongoing process that is taking place today. Bacteria evolve and resist antibiotics, viruses reinvent themselves and are able to evade new medications and animals alter their behavior to the changing climate. The changes that result are often visible.
But it wasn't until the late 1980s that biologists understood that natural selection can be seen in action, as well. The key is the fact that different traits can confer the ability to survive at different rates as well as reproduction, and may be passed down from generation to generation.
In the past, when one particular allele, the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it could rapidly become more common than the other alleles. In time, this could mean that the number of moths with black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to observe evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from one strain. Samples from each population were taken regularly, and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's research has demonstrated 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 some people find difficult to accept.
Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas that have used insecticides. This is due to pesticides causing an enticement that favors individuals who have resistant genotypes.
The rapidity of evolution has led to an increasing awareness of its significance particularly in a world that is largely shaped by human activity. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding evolution can help you make better decisions about the future of the planet and its inhabitants.