Are You Getting The Most You Evolution Site?

The Academy's Evolution Site

The concept of biological evolution is among the most fundamental concepts in biology. The Academies are committed to helping those who are interested in science to learn about the theory of evolution and how it is permeated in all areas of scientific research.

This site offers a variety of tools for teachers, students, and general readers on evolution. It includes important video clips from NOVA and WGBH's science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that represents the interconnectedness of life. It is a symbol of love and harmony in a variety of cultures. It can be used in many practical ways in addition to providing a framework to understand the evolution of species and how they respond to changing environmental conditions.

The first attempts at depicting the world of biology focused on the classification of species into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, which relied on sampling of different parts of living organisms, or small fragments of their DNA greatly increased the variety of organisms that could be included in a tree of life2. These trees are largely composed by eukaryotes, and bacterial diversity is vastly underrepresented3,4.

Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular techniques enable us to create trees by using sequenced markers such as the small subunit ribosomal RNA gene.

Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is particularly true for microorganisms, which are difficult to cultivate and are usually only represented in a single sample5. A recent analysis of all genomes that are known has created a rough draft of the Tree of Life, including numerous archaea and bacteria that are not isolated and which are not well understood.

This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine whether specific habitats require protection. The information can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing crops. The information is also incredibly beneficial in conservation efforts. It can aid biologists in identifying areas that are most likely to have cryptic species, which may have vital metabolic functions and are susceptible to the effects of human activity. Although funds to safeguard biodiversity are vital however, the most effective method to protect the world's biodiversity is for more people living in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny is also known as an evolutionary tree, shows the relationships between 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 that illustrates the evolution of taxonomic groups. 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 Identifies the relationships between organisms with similar characteristics and have evolved from a common ancestor. These shared traits can be either homologous or analogous. Homologous traits are similar in their evolutionary roots, while analogous traits look like they do, but don't have the same ancestors. Scientists put similar traits into a grouping referred to as a clade. For example, all of the organisms in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor that had these eggs. The clades are then linked to form a phylogenetic branch to identify organisms that have the closest relationship to.

Scientists utilize DNA or RNA molecular data to construct a phylogenetic graph that is more accurate and detailed. This information is more precise and provides evidence of the evolution of an organism. Researchers can use Molecular Data to calculate the age of evolution of organisms and determine how many species have a common ancestor.

The phylogenetic relationships between species can be influenced by several factors, including phenotypic plasticity a type of behavior that changes in response to unique environmental conditions. This can cause a trait to appear more resembling to one species than to the other which can obscure the phylogenetic signal. However, this problem can be reduced by the use of techniques such as cladistics which include a mix of similar and homologous traits into the tree.

In addition, phylogenetics can aid in predicting the duration and rate of speciation. This information can assist conservation biologists in making decisions about which species to save from extinction. In the end, it's the preservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept in evolution is that organisms change over time as a result of their interactions with their environment. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could develop according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of certain traits can result in changes that can be passed on to future generations.

In the 1930s and 1940s, concepts from various fields, including natural selection, genetics, and particulate inheritance -- came together to create the modern synthesis of evolutionary theory that explains how evolution happens through the variation of genes within a population and how those variations change over time as a result of natural selection. This model, known as genetic drift or mutation, gene flow, and sexual selection, is a cornerstone of the current evolutionary biology and is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species through genetic drift, mutation, and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, in conjunction with others such as directional selection and gene erosion (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time and changes in the phenotype (the expression of genotypes in individuals).

Students can better understand the concept of phylogeny by using evolutionary thinking throughout all areas of biology. A recent study by Grunspan and colleagues, for instance revealed that teaching students about the evidence that supports evolution increased students' understanding of evolution in a college-level biology course. For more details on how to teach about evolution read The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily: a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution through studying fossils, comparing species and observing living organisms. Evolution is not a past moment; it is an ongoing process that continues to be observed today. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior because of a changing environment. The results are usually evident.

It wasn't until the late 1980s when biologists began to realize that natural selection was in play. The reason is that different traits have 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 controls coloration - was present in a population of interbreeding organisms, it might rapidly become more common than all other alleles. 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.

It is easier to observe evolutionary change when the species, like bacteria, has a high generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples from each population are taken regularly and over fifty thousand generations have been observed.

Lenski's work has demonstrated that a mutation can profoundly alter the rate at the rate at which a population reproduces, and consequently the rate at which it alters.  에볼루션바카라사이트  demonstrates that evolution takes time, which is difficult for some to accept.

Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides are used. This is because pesticides cause an enticement that favors those who have resistant genotypes.

The speed at which evolution can take place has led to an increasing recognition of its importance in a world shaped by human activity, including climate change, pollution, and the loss of habitats which prevent many species from adapting. Understanding the evolution process will assist you in making better choices about the future of the planet and its inhabitants.