The concept of biological evolution is a fundamental concept in biology. The Academies are committed to helping those who are interested in the sciences understand evolution theory and how it is incorporated in all areas of scientific research.This site provides a wide range of resources for teachers, students, and general readers 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, represents the interconnectedness of all life. It is a symbol of love and unity across many cultures. It can be used in many practical ways as well, including providing a framework to understand the history of species, and how they react 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 the sampling of various parts of living organisms, or sequences of short DNA fragments, 에볼루션 카지노 사이트 greatly increased the variety of organisms that could be included in a tree of life2. However, these trees are largely comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4.
By avoiding the need for direct observation and experimentation, genetic techniques have made it possible to depict the Tree of Life in a much more accurate way. Particularly, molecular methods enable us to create trees by using sequenced markers, such as the small subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are usually only found in a single specimen5. A recent analysis of all genomes resulted in an unfinished draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that haven't yet been isolated or the diversity of which is not thoroughly understood6.
This expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine whether specific habitats require special protection. This information can be utilized in a variety of ways, such as finding new drugs, fighting diseases and improving the quality of crops. This information is also extremely valuable to conservation efforts. It can help biologists identify those areas that are most likely contain cryptic species with potentially important metabolic functions that could be at risk from anthropogenic change. Although funds to protect biodiversity are essential but the most effective way to ensure the preservation of biodiversity around the world is for more people in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny (also known as an evolutionary tree) illustrates the relationship between different organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic categories using molecular information and morphological similarities or differences. The role of phylogeny is crucial in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits can be either analogous or homologous. Homologous traits are similar in their evolutionary origins, while analogous traits look similar but do not have the same ancestors. Scientists combine similar traits into a grouping referred to as a Clade. Every organism in a group share a characteristic, like amniotic egg production. They all came from an ancestor who had these eggs. The clades are then linked to create a phylogenetic tree to determine which organisms have the closest relationship to.
Scientists utilize DNA or RNA molecular data to construct a phylogenetic graph which is more precise and detailed. This information is more precise and provides evidence of the evolution of an organism. Researchers can utilize Molecular Data to estimate the age of evolution of organisms and determine how many organisms have a common ancestor.
The phylogenetic relationships between species can be affected by a variety of factors, including phenotypic flexibility, a kind of behavior that alters in response to unique environmental conditions. This can cause a particular trait to appear more similar to one species than another, clouding the phylogenetic signal. However, this problem can be cured by the use of techniques such as cladistics that include a mix of similar and homologous traits into the tree.
Additionally, phylogenetics aids predict the duration and rate of speciation. This information will assist conservation biologists in making decisions about which species to save from disappearance. In the end, it is the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their surroundings. 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 proposed that a living organism develop slowly in accordance with its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that could be passed on to the offspring.
In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance, merged to form a modern evolutionary theory. This defines 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 is known as genetic drift mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have shown that variations can be introduced into a species through mutation, genetic drift and reshuffling of genes during sexual reproduction, as well as through the movement of populations. These processes, along with others, such as directional selection and gene erosion (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in individuals).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. In a recent study conducted by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their acceptance of evolution during a college-level course in biology. To find out more about how to teach about evolution, 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 studying fossils, comparing species, and observing living organisms. However, evolution isn't something that happened in the past, it's an ongoing process taking place in the present. Bacteria evolve and resist antibiotics, viruses re-invent themselves and elude new medications and animals alter their behavior to the changing climate. The changes that occur are often visible.
It wasn't until late 1980s that biologists began realize that natural selection was in play. The key is that various traits confer different rates of survival and reproduction (differential fitness), and can be transferred 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 prevalent than any other allele. As time passes, that could mean the number of black moths within 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 evolution when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from one strain. Samples from each population have been taken regularly and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the rate at which a population reproduces. It also shows that evolution is slow-moving, a fact that some people are unable to accept.
Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more prevalent in populations where insecticides have been used. Pesticides create a selective pressure which favors those who have resistant genotypes.
The rapidity of evolution has led to a growing awareness of its significance particularly in a world which is largely shaped by human activities. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding the evolution process can help us make better decisions about the future of our planet as well as the lives of its inhabitants.
