The Academy's Evolution Site
Biology is a key concept in biology. The Academies are involved in helping those interested in science comprehend the evolution theory and how it can be applied across all areas of scientific research.
에볼루션 슬롯 provides a range of resources for students, teachers as well as general readers about 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 symbolizes the interconnectedness of all life. It is a symbol of love and harmony in a variety of cultures. click the following article has numerous practical applications as well, including providing a framework to understand the history of species and how they react to changes in environmental conditions.
Early attempts to describe the world of biology were based on categorizing organisms based on their metabolic and physical characteristics. These methods, based on sampling of different parts of living organisms or on sequences of short fragments of their DNA significantly increased the variety that could be represented in the tree of life2. The trees are mostly composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular techniques such as the small subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However, there is still much diversity to be discovered. This is particularly true of microorganisms, which are difficult to cultivate and are often only present in a single specimen5. A recent analysis of all genomes that are known has produced a rough draft version of the Tree of Life, including numerous archaea and bacteria that have not been isolated, and which are not well understood.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, assisting to determine if certain habitats require special protection. This information can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing the quality of crop yields. The information is also incredibly valuable in conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with potentially important metabolic functions that may be at risk of anthropogenic changes. While funds to protect biodiversity are important, the most effective method to preserve 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, shows the connections between various groups of organisms. Utilizing molecular data as well as morphological similarities and distinctions or ontogeny (the course of development of an organism), scientists can build an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic groups. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that have evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous traits are similar in terms of their evolutionary paths. Analogous traits might appear similar but they don't have the same ancestry. Scientists organize similar traits into a grouping called a Clade. All organisms in a group share a characteristic, like amniotic egg production. They all evolved from an ancestor who had these eggs. The clades then join to form a phylogenetic branch to determine which organisms have the closest connection to each other.
For a more detailed and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to determine the relationships among organisms. This information is more precise than the morphological data and gives evidence of the evolutionary history of an individual or group. The use of molecular data lets researchers identify the number of organisms that have a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships of organisms are influenced by many factors including phenotypic plasticity, a type of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another, clouding the phylogenetic signal. However, this problem can be reduced by the use of techniques such as cladistics which combine homologous and analogous features into the tree.
Additionally, phylogenetics can help determine the duration and rate at which speciation takes place. This information can help conservation biologists decide the species they should safeguard from extinction. Ultimately, it is the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme of evolution is that organisms develop various characteristics over time as a result of their interactions with their environment. Many theories of evolution have been developed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that can be passed onto offspring.
In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance, came together to form a contemporary evolutionary theory. This explains how evolution occurs by the variation of genes in the population, and how these variants alter over time due to natural selection. This model, which incorporates genetic drift, mutations, gene flow and sexual selection can be mathematically described mathematically.
Recent advances in evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species by mutations, genetic drift and reshuffling of genes during sexual reproduction and the movement 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 which is defined by changes in the genome of the species over time, and the change in phenotype as time passes (the expression of the genotype in an individual).
Incorporating evolutionary thinking into all areas of biology education can increase student understanding of the concepts of phylogeny as well as evolution. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence that supports evolution helped students accept the concept of evolution in a college biology class. To find out 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 Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally looked at evolution through the past, studying fossils, and comparing species. They also observe living organisms. Evolution isn't a flims event; it is an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, viruses evolve and elude new medications, and animals adapt their behavior to the changing environment. The changes that result are often easy to see.
It wasn't until the 1980s when biologists began to realize that natural selection was in action. The reason is that different traits have different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.
In the past, if one allele - the genetic sequence that determines color - was found in a group of organisms that interbred, it could become more common than any other allele. In time, this could mean that the number of moths that have black pigmentation in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to track evolutionary change when the species, like bacteria, has a high generation turnover. Since 1988 the 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 fifty thousand generations have passed.
Lenski's work has demonstrated 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 proves that evolution is slow-moving, a fact that some people are unable to accept.
Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more common in populations where insecticides have been used. This is due to pesticides causing an exclusive pressure that favors those who have resistant genotypes.
The rapid pace of evolution taking place has led to a growing recognition of its importance in a world shaped by human activity, including climate change, pollution and the loss of habitats that prevent many species from adjusting. Understanding the evolution process will help us make better decisions regarding the future of our planet as well as the life of its inhabitants.