The Academy's Evolution Site
Biology is a key concept in biology. 에볼루션 무료체험 are involved in helping those who are interested in science learn about the theory of evolution and how it can be applied throughout all fields of scientific research.
This site provides teachers, students and general readers with a range of learning resources on evolution. It has important video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is seen in a variety of cultures and spiritual beliefs as an emblem of unity and love. It also has practical uses, like providing a framework to understand the evolution of species and how they react to changes in environmental conditions.
The earliest attempts to depict the world of biology focused on the classification of organisms into distinct categories that were identified by their physical and metabolic characteristics1. These methods, which relied on the sampling of various parts of living organisms or sequences of short fragments of their DNA greatly increased the variety of organisms that could be represented in the tree of life2. However these trees are mainly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.
Genetic techniques have greatly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods enable us to create trees by using sequenced markers, such as the small subunit of ribosomal RNA gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and which are usually only present in a single sample5. Recent analysis of all genomes resulted in an unfinished draft of a Tree of Life. This includes a large number of archaea, bacteria and other organisms that have not yet been identified or the diversity of which is not thoroughly understood6.
에볼루션 바카라 무료체험 expanded Tree of Life can be used to determine the diversity of a specific area and determine if specific habitats need special protection. This information can be used in a range of ways, from identifying the most effective remedies to fight diseases to improving crops. This information is also valuable for conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species that could have important metabolic functions that may be vulnerable to anthropogenic change. While funding to protect biodiversity are important, the most effective method to protect the biodiversity of the world is to equip the people of developing nations with the knowledge they need to take action locally and encourage conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) shows the relationships between species. Scientists can construct an phylogenetic chart which shows the evolutionary relationship of taxonomic groups using molecular data and morphological similarities or differences. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms that have similar traits and evolved from a common ancestor. These shared traits can be analogous or homologous. Homologous characteristics are identical in their evolutionary journey. Analogous traits might appear similar but they don't share the same origins. Scientists group similar traits together into a grouping called a the clade. All organisms in a group have a common trait, such as amniotic egg production. They all derived from an ancestor who had these eggs. The clades then join to form a phylogenetic branch that can identify organisms that have the closest relationship.
Scientists utilize DNA or RNA molecular data to build a phylogenetic chart which is more precise and precise. This data is more precise than morphological data and gives evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to determine the evolutionary age of living organisms and discover the number of organisms that 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 behaviour that can change due to specific environmental conditions. This can cause a trait to appear more similar to one species than another which can obscure the phylogenetic signal. However, this issue can be cured by the use of techniques like cladistics, which include a mix of analogous and homologous features into the tree.
Furthermore, phylogenetics may help predict the length and speed of speciation. This information can assist conservation biologists in making decisions about which species to protect from disappearance. 에볼루션 is ultimately the preservation of phylogenetic diversity which will result in a complete and balanced ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms change over time due to their interactions with their environment. A variety of theories about evolution have been proposed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to 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 use or disuse of traits can cause changes that could be passed onto offspring.
In the 1930s and 1940s, ideas from a variety of fields -- including genetics, natural selection and particulate inheritance -- came together to create the modern evolutionary theory synthesis which explains how evolution is triggered by the variations of genes within a population, and how those variants change in time as a result of natural selection. This model, which encompasses genetic drift, mutations in gene flow, and sexual selection, can be mathematically described mathematically.
Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species through mutation, genetic drift, and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, as well as other ones like the directional selection process and the erosion of genes (changes in frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time and changes in phenotype (the expression of genotypes within individuals).
Students can better understand phylogeny by incorporating evolutionary thinking into all aspects of biology. In a recent study conducted by Grunspan and co., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution during an undergraduate biology course. 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 in Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution by looking back--analyzing fossils, comparing species, and observing living organisms. Evolution isn't a flims moment; it is an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, viruses reinvent themselves and escape new drugs, and animals adapt their behavior in response to a changing planet. The changes that occur are often apparent.
However, it wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The key is that different traits confer different rates of survival and reproduction (differential fitness), and can be passed from one generation to the next.
In the past, if an allele - the genetic sequence that determines colour was found in a group of organisms that interbred, it might become more common than any other allele. In time, this could mean that the number of moths that have 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.
The ability to observe evolutionary change is easier when a particular 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 every day and more than 500.000 generations have been observed.
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 evolution takes time, a fact that is hard for some to accept.
Another example of microevolution is that mosquito genes that are resistant to pesticides appear more frequently in populations in which insecticides are utilized. This is because pesticides cause an exclusive pressure that favors those with resistant genotypes.
The rapid pace at which evolution can take place has led to a growing appreciation of its importance in a world shaped by human activity--including climate changes, pollution and the loss of habitats that prevent many species from adapting. Understanding evolution can aid you in making better decisions regarding the future of the planet and its inhabitants.