The Academy's Evolution Site
Biology is a key concept in biology. The Academies have been for a long time involved in helping people who are interested in science comprehend the theory of evolution and how it affects all areas of scientific exploration.
This site provides teachers, students and general readers with a range of educational resources on evolution. It also includes important video clips 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 an emblem of love and harmony in a variety of cultures. It also has practical applications, like providing a framework for understanding the history of species and how they respond to changing environmental conditions.
The first attempts to depict the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, based on sampling of different parts of living organisms or on sequences of short DNA fragments, greatly increased the variety of organisms that could be represented in a tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods enable us to create trees by using sequenced markers such as the small subunit of ribosomal RNA gene.
Despite the massive growth of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is particularly true of microorganisms that are difficult to cultivate and are often only present in a single specimen5. A recent analysis of all genomes has produced an unfinished draft of the Tree of Life. This includes a wide range of archaea, bacteria, and other organisms that haven't yet been isolated, or their diversity is not fully understood6.
The expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if particular habitats need special protection. This information can be utilized in a range of ways, from identifying the most effective remedies to fight diseases to enhancing crops. The information is also valuable in conservation efforts. It can aid biologists in identifying the areas that are most likely to contain cryptic species with potentially important metabolic functions that may be at risk from anthropogenic change. Although funding to protect biodiversity are essential however, the most effective method to protect the world's biodiversity is for more people in developing countries to be empowered with the knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny is also known as an evolutionary tree, reveals the connections between different groups of organisms. Using molecular data as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree which illustrates the evolutionary relationship between taxonomic categories. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestors. These shared traits could be either homologous or analogous. Homologous traits are identical in their evolutionary roots, while analogous traits look similar but do not have the identical origins. Scientists group similar traits into a grouping referred to as a clade. Every organism in a group share a characteristic, for example, amniotic egg production. They all evolved from an ancestor that had these eggs. The clades then join 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 that is more accurate and precise. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can use Molecular Data to determine the age of evolution of organisms and determine the number of organisms that have an ancestor common to all.
The phylogenetic relationships between organisms can be influenced by several factors including phenotypic plasticity, a kind of behavior that changes in response to specific environmental conditions. This can make a trait appear more similar to one species than to the other and obscure the phylogenetic signals. This problem can be addressed by using cladistics, which is a an amalgamation of homologous and analogous traits in the tree.
Furthermore, phylogenetics may help predict the length and speed of speciation. This information can assist conservation biologists in deciding which species to safeguard from extinction. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms change over time as a result of their interactions with their environment. Many theories of evolution have been developed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its needs and needs, 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 misuse of traits cause changes that can be passed onto offspring.
In the 1930s and 1940s, concepts from a variety of fields -- including genetics, natural selection, and particulate inheritance - came together to create the modern evolutionary theory which explains how evolution is triggered by the variation of genes within a population, and how these variants change over time as a result of natural selection. This model, which includes genetic drift, mutations, gene flow and sexual selection can be mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have shown that variation can be introduced into a species through mutation, genetic drift and reshuffling of genes in sexual reproduction, and also through migration between populations. similar site , as well as others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time) can lead to evolution which is defined by change in the genome of the species over time, and also the change in phenotype as time passes (the expression of the genotype in the individual).
Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny and evolution. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence supporting evolution increased students' understanding of evolution in a college-level biology class. For more details on how to teach about evolution read The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back, studying fossils, comparing species, and observing living organisms. However, evolution isn't something that occurred in the past, it's an ongoing process taking place today. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior as a result of a changing world. The resulting changes are often visible.
It wasn't until late 1980s that biologists began to realize that natural selection was in play. The key is that various characteristics result in different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.
In the past, if one particular allele - the genetic sequence that controls coloration - was present in a group of interbreeding species, it could quickly become more prevalent than all other alleles. As time passes, 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.
It is easier to see evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each population are taken every day, and over fifty thousand generations 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 shows that evolution takes time, a fact that is difficult for some to accept.
Microevolution is also evident in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides have been used. That's because the use of pesticides creates a pressure that favors individuals with resistant genotypes.
The rapidity of evolution has led to a greater awareness of its significance especially in a planet shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution can help us make better decisions about the future of our planet as well as the life of its inhabitants.