9 Signs That You're The Evolution Site Expert

The Academy's Evolution Site

Biology is one of the most fundamental concepts in biology. The Academies are committed to helping those interested in the sciences understand evolution theory and how it is permeated in all areas of scientific research.

more..  provides teachers, students and general readers with a wide range of learning resources on evolution. It has important video clips from NOVA and WGBH's 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 harmony in a variety of cultures. It also has practical applications, like providing a framework to understand the evolution of species and how they respond to changes in environmental conditions.

Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which are based on the collection of various parts of organisms, or fragments of DNA have significantly increased the diversity of a Tree of Life2. These trees are mostly populated of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Trees can be constructed by using molecular methods, such as the small-subunit ribosomal gene.

Despite the dramatic growth of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly true for microorganisms, which are difficult to cultivate and are often only present in a single sample5. A recent study of all genomes known to date has produced a rough draft version of the Tree of Life, including a large number of archaea and bacteria that have not been isolated, and whose diversity is poorly understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if specific habitats require special protection. This information can be utilized in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crop yields. It is also valuable to conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species that could have important metabolic functions that could be vulnerable to anthropogenic change. While funds to protect biodiversity are important, the best method to preserve the biodiversity of the world is to equip more people in developing countries with the knowledge they need to act locally and support conservation.

Phylogeny

A phylogeny is also known as an evolutionary tree, reveals the connections between various groups of organisms. Scientists can build an phylogenetic chart which shows the evolutionary relationship of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms with similar characteristics and have evolved from an ancestor that shared traits. These shared traits can be either analogous or homologous. Homologous traits are the same in their evolutionary path. Analogous traits may look similar but they don't have the same origins. Scientists arrange similar traits into a grouping known as a the clade. For instance, all of the species in a clade have the characteristic of having amniotic eggs and evolved from a common ancestor that had eggs. The clades are then linked to create a phylogenetic tree to determine which organisms have the closest connection to each other.

Scientists make use of molecular DNA or RNA data to create a phylogenetic chart that is more precise and detailed. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to determine the age of evolution of organisms and determine how many organisms have a common ancestor.

The phylogenetic relationships of a species can be affected by a number of factors such as the phenotypic plasticity. This is a type of behaviour that can change as a result of specific environmental conditions. This can cause a trait to appear more similar to a species than to another, obscuring the phylogenetic signals. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous traits in the tree.

In addition, phylogenetics helps determine the duration and rate at which speciation takes place. This information can aid conservation biologists to decide the species they should safeguard from extinction. It is ultimately the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms alter over time because of their interactions with their environment. Several theories of evolutionary change have been proposed by a wide range of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that could be passed on to offspring.

In the 1930s and 1940s, concepts from various areas, including genetics, natural selection and particulate inheritance, merged to form a contemporary evolutionary theory. This defines how evolution is triggered by the variation in genes within a population and how these variants alter over time due to natural selection. This model, which incorporates mutations, genetic drift as well as gene flow and sexual selection is mathematically described.

Recent discoveries in evolutionary developmental biology have demonstrated how variations can be introduced to a species through genetic drift, mutations and reshuffling of genes during sexual reproduction, and even migration between populations. These processes, 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 that is defined as change in the genome of the species over time and the change in phenotype as time passes (the expression of the genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education could increase students' understanding of phylogeny and evolutionary. In a recent study conducted by Grunspan et al., it was shown that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. For more information on how to teach about evolution, please see The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally looked at evolution through the past, analyzing fossils and comparing species. They also observe living organisms. But evolution isn't a thing that happened in the past. It's an ongoing process that is happening today. Bacteria evolve and resist antibiotics, viruses evolve and elude new medications and animals change their behavior in response to the changing environment. The results are usually evident.

It wasn't until the 1980s that biologists began to realize that natural selection was in action. The key is that different traits confer different rates of survival and reproduction (differential fitness) and are 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 species, it could quickly become more common than other alleles. Over time, this would mean that the number of moths that have black pigmentation in a population may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Monitoring evolutionary changes in action is easier when a particular species has a rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. Samples from each population were taken regularly and more than 500.000 generations of E.coli have passed.

Lenski's work has demonstrated that mutations can drastically alter the speed at which a population reproduces and, consequently the rate at which it changes. It also proves that evolution takes time--a fact that some find difficult to accept.

Another example of microevolution is the way mosquito genes that are resistant to pesticides show up more often in populations where insecticides are used. That's because the use of pesticides creates a pressure that favors individuals who have resistant genotypes.

The rapidity of evolution has led to an increasing recognition of its importance, especially in a world shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding evolution will help us make better choices about the future of our planet and the lives of its inhabitants.