10 Things Everybody Hates About Evolution Site
The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies are committed to helping those who are interested in science comprehend the evolution theory and how it is incorporated throughout all fields of scientific research.
This site offers a variety of sources for students, teachers as well as general readers about evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of all life. It is used in many cultures and spiritual beliefs as symbolizing unity and love. It also has practical uses, like providing a framework for understanding the evolution of species and how they react to changing environmental conditions.
The first attempts at depicting the biological world focused on separating organisms into distinct categories which had been distinguished by physical and metabolic characteristics1. These methods rely on the sampling of different parts of organisms or fragments of DNA have significantly increased the diversity of a Tree of Life2. These trees are largely composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
Genetic techniques have greatly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques enable us to create trees by using sequenced markers such as the small subunit ribosomal gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are usually found in a single specimen5. Recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a wide range of archaea, bacteria, and other organisms that haven't yet been identified or their diversity is not thoroughly understood6.
The expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if specific habitats require special protection. The information is useful in many ways, including finding new drugs, fighting diseases and improving the quality of crops. This information is also valuable in conservation efforts. It can help biologists identify the areas most likely to contain cryptic species with significant metabolic functions that could be at risk of anthropogenic changes. While funds to protect biodiversity are essential, the best way to conserve the world's biodiversity is to equip the people of developing nations with the information they require to take action locally and encourage conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, shows the connections between various groups of organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestors. These shared traits could be either homologous or analogous. Homologous traits are the same in terms of their evolutionary paths. Analogous traits may look similar however they do not share the same origins. Scientists organize similar traits into a grouping known as a Clade. All organisms in a group have a common characteristic, for example, amniotic egg production. They all derived from an ancestor with these eggs. The clades are then connected to create a phylogenetic tree to determine the organisms with the closest connection to each other.
For a more detailed and accurate phylogenetic tree, scientists use molecular data from DNA or RNA to establish the relationships among organisms. This information is more precise than the morphological data and provides evidence of the evolution background of an organism or group. Researchers can use Molecular Data to determine the age of evolution of organisms and identify the number of organisms that share a common ancestor.
The phylogenetic relationships between organisms can be affected by a variety of factors including phenotypic plasticity, an aspect of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more like a species another, obscuring the phylogenetic signal. However, this issue can be solved through the use of methods like cladistics, which include a mix of similar and homologous traits into the tree.
Additionally, phylogenetics can aid in predicting the length and speed of speciation. This information will assist conservation biologists in making decisions about which species to protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will create a complete and balanced ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms change over time due to their interactions with their environment. Several theories of evolutionary change have been developed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that could be passed on to offspring.
In the 1930s and 1940s, concepts from various fields, including genetics, natural selection, and particulate inheritance -- came together to create the modern evolutionary theory synthesis, which defines how evolution occurs through the variations of genes within a population and how those variations change in time as a result of natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is a key element of current evolutionary biology, and can be mathematically explained.
Recent developments in evolutionary developmental biology have revealed how variations can be introduced to a species by mutations, genetic drift, reshuffling genes during sexual reproduction and the movement between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution that is defined as changes in the genome of the species over time and also by changes in phenotype over time (the expression of that genotype in the individual).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking in all aspects of biology. A recent study by Grunspan and colleagues, for instance revealed that teaching students about the evidence that supports evolution increased students' acceptance of evolution in a college-level biology course. For more details on how to teach about evolution look up The Evolutionary Potential in All Areas of Biology or Thinking Evolution arily: 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 study living organisms. Evolution is not a distant moment; it is a process that continues today. Bacteria evolve and resist antibiotics, viruses evolve and elude new medications and animals change their behavior to the changing environment. The changes that result are often apparent.
However, it wasn't until late 1980s that biologists understood that natural selection could be seen in action, as well. The main reason is that different traits result in a different rate of survival and reproduction, and they can be passed on from generation to generation.
In the past, if one allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it might become more prevalent than any other allele. Over time, this would 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 fast generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. Samples of each population have been taken regularly, and more than 50,000 generations of E.coli have been observed to have passed.
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 alters. It also demonstrates that evolution takes time, a fact that some find hard 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. This is because pesticides cause a selective pressure which favors those with resistant genotypes.
The rapidity of evolution has led to an increasing recognition of its importance especially in a planet shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding the evolution process will help us make better decisions regarding the future of our planet as well as the life of its inhabitants.