The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those interested in science to comprehend the evolution theory and how it is permeated in all areas of scientific research.
This site provides a range of sources for students, teachers as well as general readers about evolution. It includes key video clip 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 harmony in a variety of cultures. It has numerous practical applications as well, including providing a framework for understanding the history of species, and how they respond to changing environmental conditions.
Early attempts to describe the world of biology were built on categorizing organisms based on their metabolic and physical characteristics. These methods rely on the sampling of different parts of organisms or DNA fragments have greatly increased the diversity of a Tree of Life2. These trees are mostly populated of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have greatly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. We can create trees using molecular methods such as the small subunit ribosomal gene.
Despite the rapid growth of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are usually only represented in a single specimen5. A recent analysis of all genomes that are known has produced a rough draft of the Tree of Life, including a large number of bacteria and archaea that have not been isolated and which are not well understood.
This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if specific habitats need special protection. go to the website can be used in a variety of ways, from identifying the most effective medicines to combating disease to improving crop yields. This information is also extremely beneficial to conservation efforts. It helps biologists determine the areas most likely to contain cryptic species with potentially important metabolic functions that may be vulnerable to anthropogenic change. While funds to protect biodiversity are essential, the best way to conserve the biodiversity of the world is to equip more people in developing nations with the information they require to take action locally and encourage conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between different organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationships between taxonomic groups using molecular data and morphological similarities or differences. 에볼루션 룰렛 of a tree plays an important role in understanding biodiversity, genetics and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms that have similar traits and have evolved from a common ancestor. These shared traits are either analogous or homologous. Homologous characteristics are identical in their evolutionary paths. Analogous traits could appear like they are but they don't have the same ancestry. Scientists arrange similar traits into a grouping called a clade. For example, all of the species in a clade have the characteristic of having amniotic egg and evolved from a common ancestor which had these eggs. The clades are then connected to form a phylogenetic branch that can determine which organisms have the closest connection to each other.
Scientists utilize DNA or RNA molecular data to construct a phylogenetic graph that is more precise and precise. This information is more precise than the morphological data and provides evidence of the evolution background of an organism or group. Molecular data allows researchers to identify the number of species that share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships of a species can be affected by a variety of factors such as the phenomenon of phenotypicplasticity. This is a type behavior that alters due to unique environmental conditions. This can cause a trait to appear more similar in one species than other species, which can obscure the phylogenetic signal. However, this problem can be cured by the use of methods such as cladistics which include a mix of similar and homologous traits into the tree.
Additionally, phylogenetics aids determine the duration and rate at which speciation occurs. This information can aid conservation biologists in making decisions about which species to safeguard from the threat of extinction. In the end, it is the conservation of phylogenetic variety that will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept in evolution is that organisms alter over time because of their interactions with their environment. Many theories of evolution have been proposed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits cause changes that can be passed on to offspring.
In the 1930s & 1940s, concepts from various areas, including natural selection, genetics & particulate inheritance, merged to form a modern evolutionary theory. This explains how evolution occurs by the variations in genes within the population, and how these variations alter over time due to natural selection. This model, called genetic drift, mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species by mutation, genetic drift and reshuffling of genes during sexual reproduction, as well as through migration between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a 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 in the individual).
Students can better understand phylogeny by incorporating evolutionary thinking in all areas of biology. In a recent study conducted by Grunspan and co. It was found that teaching students about the evidence for evolution increased their understanding of evolution during the course of a college biology. For more details on how to teach 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
Traditionally scientists have studied evolution by studying fossils, comparing species and studying living organisms. Evolution isn't a flims event, but an ongoing process. Bacteria mutate and resist antibiotics, viruses reinvent themselves and escape new drugs, and animals adapt their behavior to the changing climate. The results are usually easy to see.
It wasn't until the 1980s that biologists began to realize that natural selection was also at work. The reason is that different traits confer different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.
In the past, if a certain allele - the genetic sequence that determines colour was present in a population of organisms that interbred, it could become more common than other allele. Over time, this would mean that the number of moths that have black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
에볼루션 룰렛 is easier to observe evolutionary change when an organism, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. The samples of each population have been collected regularly, and more than 500.000 generations of E.coli have passed.
Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the efficiency of a population's reproduction. It also demonstrates that evolution takes time, which is hard for some to accept.
Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations where insecticides have been used. Pesticides create an exclusive pressure that favors individuals who have resistant genotypes.
The speed of evolution taking place has led to a growing recognition of its importance in a world that is shaped by human activities, including climate change, pollution, and the loss of habitats that prevent the species from adapting. Understanding evolution can assist you in making better choices about the future of our planet and its inhabitants.