The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies are involved in helping those who are interested in the sciences learn about the theory of evolution and how it is permeated across all areas of scientific research.
This site provides a range of resources for students, teachers and general readers of evolution. It contains key video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is a symbol of love and harmony in a variety of cultures. It can be used in many practical ways as well, including providing a framework to understand the history of species and how they respond to changes in environmental conditions.
Early approaches to depicting the world of biology focused on categorizing species into distinct categories that had been identified by their physical and metabolic characteristics1. These methods are based on the sampling of different parts of organisms or short fragments of DNA have greatly increased the diversity of a Tree of Life2. These trees are mostly populated by eukaryotes and bacteria are largely underrepresented3,4.
In avoiding the necessity of direct observation and experimentation, genetic techniques have made it possible to depict the Tree of Life in a more precise way. In particular, molecular methods allow us to construct trees by using sequenced markers such as the small subunit ribosomal gene.
The Tree of Life has been dramatically expanded through genome sequencing. However there is still a lot of diversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are typically only found in a single specimen5. Recent analysis of all genomes resulted in an initial draft of the Tree of Life. 에볼루션코리아 includes a variety of bacteria, archaea and other organisms that have not yet been isolated, or whose diversity has not been thoroughly understood6.
This expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if specific habitats require special protection. The information can be used in a variety of ways, from identifying new treatments to fight disease to improving crops. The information is also useful for conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species that could have important metabolic functions that could be at risk of anthropogenic changes. While funds to safeguard biodiversity are vital, ultimately the best way to protect the world's biodiversity is for more people living in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, reveals the connections between groups of organisms. Using molecular data similarities and differences in morphology or ontogeny (the process of the development of an organism) scientists can create an phylogenetic tree that demonstrates 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 with similar traits and evolved from an ancestor that shared traits. These shared traits can be homologous, or analogous. Homologous characteristics are identical in terms of their evolutionary paths. Analogous traits could appear like they are however they do not have the same origins. Scientists put similar traits into a grouping called a Clade. For instance, all the organisms in a clade share the characteristic of having amniotic egg and evolved from a common ancestor which had these eggs. The clades are then linked to form a phylogenetic branch that can identify organisms that have the closest relationship.
Scientists utilize DNA or RNA molecular data to construct a phylogenetic graph that is more precise and detailed. This information is more precise than morphological information and gives evidence of the evolutionary history of an individual or group. Researchers can utilize Molecular Data to estimate the evolutionary age of living organisms and discover how many species share a common ancestor.
The phylogenetic relationships of a species can be affected by a number of factors, including the phenotypic plasticity. This is a type of behavior that changes 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 mitigated by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous features in the tree.
Additionally, phylogenetics can help predict the duration and rate at which speciation takes place. 에볼루션 카지노 사이트 will assist conservation biologists in deciding which species to protect from disappearance. Ultimately, it is the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms acquire various characteristics over time based on their interactions with their environment. A variety of theories about evolution have been proposed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop gradually according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed 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 can be passed on to offspring.
In the 1930s and 1940s, concepts from various fields, including natural selection, genetics, and particulate inheritance - came together to create the modern synthesis of evolutionary theory that explains how evolution is triggered by the variation of genes within a population and how those variants change in time due to natural selection. This model, known as genetic drift, mutation, gene flow and sexual selection, is a key element of modern evolutionary biology and can be mathematically described.
Recent discoveries in evolutionary developmental biology have revealed how variations can be introduced to a species through genetic drift, mutations or reshuffling of genes in sexual reproduction and the movement between populations. These processes, as well as others such as the directional selection process and the erosion of genes (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in phenotype (the expression of genotypes in an individual).
Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny and evolutionary. In a recent study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution in an undergraduate biology course. For more information on how to teach evolution, see The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back, studying fossils, comparing species and observing living organisms. Evolution is not a past event, but an ongoing process. Bacteria evolve and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals change their behavior to the changing climate. The results are usually evident.
It wasn't until the 1980s when biologists began to realize that natural selection was in play. The main reason is that different traits result in a different rate of survival as well as reproduction, and may be passed down from one generation to another.
In the past, if an allele - the genetic sequence that determines color - was present in a population of organisms that interbred, it might become more prevalent than any other allele. In time, this could mean the number of black moths in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is easier when a particular species has a rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from one strain. The samples of each population have been collected regularly and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's research has revealed that mutations can drastically alter the speed at the rate at which a population reproduces, and consequently the rate at which it changes. It also shows that evolution is slow-moving, a fact that some 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 where insecticides have been used. Pesticides create a selective pressure which favors those who have resistant genotypes.
The rapid pace of evolution taking place has led to a growing appreciation of its importance in a world that is shaped by human activity, including climate changes, pollution and the loss of habitats that prevent many species from adjusting. Understanding evolution can aid you in making better decisions regarding the future of the planet and its inhabitants.