The Academy's Evolution Site
The concept of biological evolution is among the most important concepts in biology. The Academies are involved in helping those who are interested in the sciences learn about the theory of evolution and how it is permeated across all areas of scientific research.
This site provides a range of sources for teachers, students and general readers of evolution. It also includes important video clips 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 seen in a variety of religions and cultures as an emblem of unity and love. It also has important practical applications, like providing a framework for understanding the evolution of species and how they react to changes in the environment.
Early approaches to depicting the world of biology focused on the classification of organisms into distinct categories which had been identified by their physical and metabolic characteristics1. These methods, which relied on the sampling of various parts of living organisms or sequences of 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. Trees can be constructed using molecular techniques, such as the small-subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is especially the case for microorganisms which are difficult to cultivate and are usually found in one sample5. Recent analysis of all genomes resulted in an unfinished draft of a Tree of Life. This includes a wide range of archaea, bacteria and other organisms that have not yet been identified or their diversity is not well understood6.
The expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine if specific habitats require protection. The information can be used in a variety of ways, from identifying the most effective medicines to combating disease to enhancing the quality of the quality of crops. The information is also beneficial to 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 be vulnerable to the effects of human activity. While funding to protect biodiversity are important, the best way to conserve the biodiversity of the world is to equip more people in developing nations with the knowledge they need to act locally and support conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) shows the relationships between organisms. Utilizing molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolution of taxonomic categories. Phylogeny is essential in understanding evolution, biodiversity and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and have evolved from an ancestor with common traits. These shared traits could be analogous, or homologous. 에볼루션 카지노 are similar in their evolutionary path. Analogous traits might appear like they are however they do not have the same ancestry. Scientists combine similar traits into a grouping known as a clade. Every organism in a group have a common characteristic, like amniotic egg production. They all came from an ancestor who had these eggs. The clades then join to form a phylogenetic branch that can determine which organisms have the closest relationship.
Scientists utilize DNA or RNA molecular information to build a phylogenetic chart which is more precise and detailed. This information is more precise than morphological data and gives evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to estimate the age of evolution of living organisms and discover how many organisms have an ancestor common to all.
The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic plasticity an aspect of behavior that changes in response to unique environmental conditions. This can cause a particular trait to appear more similar in one species than another, clouding the phylogenetic signal. This problem can be mitigated by using cladistics, which is a an amalgamation of homologous and analogous features in the tree.
Additionally, phylogenetics aids predict the duration and rate at which speciation takes place. This information can assist conservation biologists in making choices about which species to safeguard from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will result in a complete and balanced ecosystem.
Evolutionary Theory
The fundamental concept of evolution is that organisms develop distinct characteristics over time based on their interactions with their surroundings. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can cause changes that are passed on to the
In the 1930s and 1940s, ideas from different fields, including natural selection, genetics & particulate inheritance, were brought together to form a modern evolutionary theory. This explains how evolution happens through the variations in genes within a population and how these variants change with time due to natural selection. This model, which includes genetic drift, mutations in gene flow, and sexual selection can be mathematically described mathematically.
Recent advances in evolutionary developmental biology have demonstrated how variations can be introduced to a species by genetic drift, mutations or reshuffling of genes in sexual reproduction, and even migration 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 result in evolution which is defined by changes in the genome of the species over time and the change in phenotype as time passes (the expression of that genotype in the individual).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking throughout all areas of biology. In a recent study by Grunspan et al. It was found that teaching students about the evidence for evolution increased their understanding of evolution in the course of a college biology. To learn 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 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 taking place in the present. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior because of the changing environment. The changes that result are often evident.
It wasn't until the late 1980s that biologists began realize that natural selection was in play. The key is that different characteristics result in 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 could become more common than any other allele. As time passes, this could mean that the number of moths sporting black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to see evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. The 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 work has demonstrated that mutations can drastically alter the rate at which a population reproduces--and so, the rate at which it changes. It also demonstrates that evolution takes time, a fact that some people find difficult to accept.
Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations that have used insecticides. That's because the use of pesticides creates a selective pressure that favors those with resistant genotypes.
The speed of evolution taking place has led to an increasing appreciation of its importance in a world shaped by human activity--including climate change, pollution, and the loss of habitats that prevent the species from adapting. Understanding the evolution process can help us make better decisions regarding the future of our planet as well as the life of its inhabitants.