The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have been active for a long time in helping people who are interested in science comprehend the theory of evolution and how it permeates all areas of scientific exploration.
This site provides a range of tools for students, teachers as well as general readers about evolution. It contains the most important video clips from NOVA and WGBH-produced 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 has many practical applications as well, including providing a framework for understanding the history of species and how they react to changes in environmental conditions.
The earliest attempts to depict the world of biology focused on categorizing species into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, which rely on the collection of various parts of organisms, or DNA fragments, have greatly increased the diversity of a tree of Life2. However these trees are mainly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.
In avoiding the necessity of direct observation and experimentation genetic techniques have made it possible to represent the Tree of Life in a more precise way. In particular, molecular methods allow us to build trees by using sequenced markers like the small subunit ribosomal RNA gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and are typically found in one sample5. Recent analysis of all genomes resulted in an initial draft of a Tree of Life. This includes a wide range of archaea, bacteria, and other organisms that haven't yet been identified or the diversity of which is not thoroughly understood6.
The expanded Tree of Life can be used to determine the diversity of a particular area and determine if certain habitats need special protection. This information can be used in many ways, including identifying new drugs, combating diseases and enhancing crops. This information is also extremely useful to conservation efforts. It can aid biologists in identifying the areas that are most likely to contain cryptic species with potentially important metabolic functions that could be at risk of anthropogenic changes. While funding to protect biodiversity are important, the best method to preserve the biodiversity of the world is to equip more people in developing countries with the knowledge they need to act locally and promote conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, shows the relationships between various groups of organisms. Using molecular data similarities and differences in morphology or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree which illustrates the evolution of taxonomic groups. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestors. These shared traits can be either analogous or homologous. Homologous traits are similar in their evolutionary roots, while analogous traits look similar, but do not share the same ancestors. Scientists arrange similar traits into a grouping called a the clade. Every organism in a group have a common characteristic, like amniotic egg production. They all evolved from an ancestor who had these eggs. The clades are then connected to form a phylogenetic branch that can identify organisms that have the closest connection to each other.
Scientists utilize molecular DNA or RNA data to create a phylogenetic chart that is more accurate and precise. This data is more precise than morphological information and provides evidence of the evolutionary background of an organism or group. Researchers can use Molecular Data to determine the evolutionary age of organisms and identify how many organisms share an ancestor common to all.
The phylogenetic relationships between organisms can be influenced by several factors including phenotypic plasticity, a kind of behavior that alters in response to specific environmental conditions. This can cause a particular trait to appear more like a species other species, which can obscure the phylogenetic signal. However, this problem can be solved through the use of methods such as cladistics which combine homologous and analogous features into the tree.
Additionally, phylogenetics can help determine the duration and rate of speciation. This information can aid conservation biologists to decide which species they should protect from extinction. In the end, it is the conservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept in evolution is that organisms change over time as a result of their interactions with their environment. Several theories of evolutionary change have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that could be passed on to the offspring.
In 에볼루션바카라사이트 & 1940s, ideas from different fields, such as genetics, natural selection, and particulate inheritance, merged to create a modern theorizing of evolution. This defines how evolution happens through the variations in genes within a population and how these variants change with time due to natural selection. This model, which encompasses genetic drift, mutations in gene flow, and sexual selection can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species through mutation, genetic drift, and reshuffling of genes during sexual reproduction, as well as by migration between populations. These processes, as well as others 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 the change in phenotype as time passes (the expression of the genotype in an individual).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. A recent study conducted by Grunspan and colleagues, for example demonstrated that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. To find out more about how to teach about evolution, see The Evolutionary Potential of all Areas of Biology and 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 studying living organisms. Evolution isn't a flims moment; it is a process that continues today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior because of the changing environment. The resulting changes are often easy to see.
But it wasn't until the late-1980s that biologists realized that natural selection could be seen in action, as well. The key is the fact that different traits confer an individual rate of survival as well as reproduction, and may be passed on from generation to generation.
In the past, if one particular allele - the genetic sequence that defines color in a group of interbreeding species, it could rapidly become more common than all other alleles. As time passes, this could mean that the number of moths sporting black pigmentation in a group could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Monitoring evolutionary changes in action is easier when a species has a rapid turnover of its generation like bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples from each population are taken on a regular basis, and over 50,000 generations have now passed.
Lenski's research has revealed that mutations can alter the rate at which change occurs and the efficiency at which a population reproduces. It also demonstrates that evolution takes time, something that is hard for some to accept.
Another example of microevolution is how mosquito genes that are resistant to pesticides show up more often in populations where insecticides are used. This is due to pesticides causing a selective pressure which favors those with resistant genotypes.
The rapid pace at which evolution can take place has led to an increasing awareness of its significance in a world shaped by human activity, including climate changes, pollution and the loss of habitats that prevent the species from adapting. Understanding evolution will help you make better decisions regarding the future of the planet and its inhabitants.