The Academy's Evolution Site
Biology is one of the most central concepts in biology. 에볼루션 슬롯 are committed to helping those who are interested in science comprehend the evolution theory and how it is permeated across all areas of scientific research.
This site provides students, teachers and general readers with a wide range of educational resources on 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, symbolizes the interconnectedness of all life. It is used in many cultures and spiritual beliefs as an emblem of unity and love. It has numerous practical applications in addition to providing a framework to understand the history of species, and how they respond to changes in environmental conditions.
Early approaches to depicting the biological world focused on separating organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, which relied on sampling of different parts of living organisms or on small fragments of their DNA significantly expanded the diversity that could be represented in a tree of life2. These trees are mostly populated by eukaryotes and bacteria are largely underrepresented3,4.
By avoiding the need for direct observation and experimentation genetic techniques have allowed us to represent the Tree of Life in a much more accurate way. We can construct trees using molecular methods such as the small subunit ribosomal gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. This is especially true for microorganisms that are difficult to cultivate and are usually found in one sample5. A recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a variety of archaea, bacteria and other organisms that have not yet been isolated, or their diversity is not well understood6.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine whether specific habitats require special protection. This information can be utilized in many ways, including finding new drugs, battling diseases and improving the quality of crops. It is also valuable for conservation efforts. It can aid biologists in identifying areas that are most likely to have species that are cryptic, which could perform important metabolic functions and are susceptible to changes caused by humans. While conservation funds are important, the best way to conserve the world's biodiversity is to equip more people in developing nations with the necessary knowledge to take action locally and encourage conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, reveals the connections between different groups of organisms. Using molecular data, morphological similarities and differences, or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. The role of phylogeny is crucial in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from an ancestor with common traits. These shared traits are either analogous or homologous. Homologous characteristics are identical in their evolutionary path. Analogous traits could appear similar but they don't have the same ancestry. Scientists combine similar traits into a grouping called a the clade. All members of a clade share a characteristic, for example, amniotic egg production. They all evolved from an ancestor who had these eggs. The clades are then linked to create a phylogenetic tree to identify organisms that have the closest connection to each other.
Scientists utilize DNA or RNA molecular data to create a phylogenetic chart that is more precise and precise. This information is more precise and gives evidence of the evolutionary history of an organism. Molecular data allows researchers to determine the number of species that have the same ancestor and estimate their evolutionary age.
The phylogenetic relationships of organisms can be affected by a variety of factors, including phenotypic plasticity an aspect of behavior that alters in response to unique environmental conditions. This can cause a trait to appear more similar to a species than another which can obscure the phylogenetic signal. However, this problem can be reduced by the use of techniques such as cladistics which incorporate a combination of homologous and analogous features into the tree.
In addition, phylogenetics helps determine the duration and rate of speciation. This information can assist conservation biologists decide which species they should protect from extinction. It is ultimately the preservation of phylogenetic diversity that will result in an ecologically balanced and complete ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms develop different features over time based on their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would develop according to its own needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of traits can lead to changes that can be passed on to future generations.
In the 1930s & 1940s, concepts from various fields, such as natural selection, genetics & particulate inheritance, came together to form a contemporary evolutionary theory. This defines how evolution occurs by the variation of genes in the population and how these variants change over time as a result of natural selection. This model, known as genetic drift or mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and is mathematically described.
Recent discoveries in evolutionary developmental biology have demonstrated how variations can be introduced to a species through genetic drift, mutations, reshuffling genes during sexual reproduction and 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 which is defined by change in the genome of the species over time and also the change in phenotype over time (the expression of the genotype within the individual).
Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny and evolutionary. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence supporting evolution increased students' understanding of evolution in a college-level biology course. For more details on how to teach about evolution read The Evolutionary Potency 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 by studying fossils, comparing species and observing living organisms. However, evolution isn't something that occurred in the past, it's an ongoing process that is happening right now. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior because of a changing world. The results are usually easy to see.
It wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and are transferred from one generation to the next.
In the past, if a certain allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could become more prevalent than any other allele. As time passes, that could mean the number of black moths in a particular population could rise. 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. coli that descended from a single strain; samples of each are taken on a regular basis, and over 500.000 generations have been observed.
Lenski's research has shown that a mutation can profoundly alter the speed at which a population reproduces and, consequently the rate at which it alters. It also demonstrates that evolution is slow-moving, a fact that some find difficult to accept.
Another example of microevolution is how mosquito genes that confer resistance to pesticides show up more often in areas where insecticides are used. Pesticides create an exclusive pressure that favors those with resistant genotypes.
The rapid pace at which evolution takes place has led to an increasing awareness of its significance in a world that is shaped by human activity, including climate change, pollution, and the loss of habitats that hinder the species from adapting. Understanding evolution will help us make better decisions regarding the future of our planet as well as the lives of its inhabitants.