The 12 Most Popular Evolution Site Accounts To Follow On Twitter
The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have been active for a long time in helping people who are interested in science understand the theory of evolution and how it permeates all areas of scientific exploration.
This site provides teachers, students and general readers with a variety of learning resources about evolution. It contains key video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that represents the interconnectedness of life. It is seen in a variety of cultures and spiritual beliefs as symbolizing unity and love. It has numerous practical applications in addition to providing a framework for understanding the history of species, and how they respond to changes in environmental conditions.
The first attempts at depicting the world of biology focused on categorizing species into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of organisms or short fragments of DNA, have significantly increased the diversity of a tree of Life2. These trees are mostly populated by eukaryotes and bacterial diversity is vastly underrepresented3,4.
Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular techniques like the small-subunit ribosomal gene.
The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of diversity to be discovered. This is particularly the case for microorganisms which are difficult to cultivate and are usually present in a single sample5. Recent analysis of all genomes resulted in an initial draft of the Tree of Life. This includes a wide range of archaea, bacteria and other organisms that have not yet been isolated or whose diversity has not been thoroughly understood6.
This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if certain habitats need special protection. This information can be used in a range of ways, from identifying new medicines to combating disease to enhancing crops. This information is also extremely beneficial in conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which could have vital metabolic functions and are susceptible to the effects of human activity. Although funds to protect biodiversity are crucial but the most effective way to ensure the preservation of biodiversity around the world is for more people in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny (also called an evolutionary tree) shows the relationships between species. Using molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestral. These shared traits could be either homologous or analogous. Homologous traits are similar in their evolutionary roots, while analogous traits look similar but do not have the same origins. Scientists organize similar traits into a grouping referred to as a Clade. All organisms in a group have a common characteristic, like amniotic egg production. They all came from an ancestor that had these eggs. The clades are then connected to form a phylogenetic branch that can determine which organisms have the closest relationship.
To create a more thorough and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the connections between organisms. This data is more precise than morphological data and provides evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to calculate the evolutionary age of organisms and determine how many species share the same ancestor.
The phylogenetic relationships between species can be affected by a variety of factors, including phenotypic flexibility, an aspect of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more similar in one species than another, obscuring the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates the combination of homologous and analogous features in the tree.
In addition, phylogenetics can aid in predicting the duration and rate of speciation. This information can assist conservation biologists make decisions about which species to protect from extinction. In the end, it's the preservation of phylogenetic diversity that will result in an ecologically balanced and complete ecosystem.
Evolutionary Theory
The fundamental concept in evolution is that organisms change over time as a result of their interactions with their environment. Several theories of evolutionary change have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that could be passed on to the offspring.
In the 1930s and 1940s, ideas from different areas, including genetics, natural selection, and particulate inheritance, merged to create a modern evolutionary theory. This describes how evolution happens through the variation in genes within a population and how these variants change with time due to natural selection. This model, known as genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of the current evolutionary biology and is mathematically described.
Recent discoveries in evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species through genetic drift, mutations and reshuffling of genes during sexual reproduction and migration between populations. These processes, as well as others, such as the directional selection process and the erosion of genes (changes to the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time, as well as changes in phenotype (the expression of genotypes in an individual).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence supporting evolution increased students' acceptance of evolution in a college-level biology course. For more information about how to teach evolution read The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also study living organisms. But evolution isn't a thing that occurred in the past, it's an ongoing process that is that is taking place in the present. Bacteria transform and resist antibiotics, viruses reinvent themselves and escape new drugs and animals alter their behavior in response to a changing planet. why not try here that result are often visible.
It wasn't until the late 1980s that biologists began realize that natural selection was at work. The reason is that different traits confer different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.
In the past, when one particular allele, the genetic sequence that defines color in a population of interbreeding organisms, it could rapidly become more common than other alleles. As time passes, that could mean that the number of black moths within the 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 observe evolutionary change when the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from one strain. Samples of each population have been taken regularly, and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's work has demonstrated that mutations can drastically alter the rate at the rate at which a population reproduces, and consequently the rate at which it evolves. It also shows evolution takes time, which is difficult for some to accept.
Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more prevalent in areas where insecticides are used. This is due to pesticides causing an exclusive pressure that favors individuals who have resistant genotypes.
The speed at which evolution takes place has led to a growing awareness of its significance in a world shaped by human activity, including climate changes, pollution and the loss of habitats which prevent the species from adapting. Understanding evolution can help us make better choices about the future of our planet, as well as the life of its inhabitants.