What Freud Can Teach Us About Evolution Site

The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies are committed to helping those interested in the sciences comprehend the evolution theory and how it can be applied throughout all fields of scientific research.

This site offers a variety of resources for students, teachers 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 is an ancient symbol that symbolizes the interconnectedness of life. It is seen in a variety of cultures and spiritual beliefs as symbolizing unity and love. It can be used in many practical ways as well, including providing a framework for understanding the history of species, and how they respond to changing environmental conditions.

The first attempts at depicting the biological world focused on separating organisms into distinct categories which had been identified by their physical and metabolic characteristics1.  에볼루션게이밍 , which rely on sampling of different parts of living organisms, or sequences of small fragments of their DNA, significantly increased the variety that could be represented in the tree of life2. The trees are mostly composed by eukaryotes, and bacterial diversity is vastly underrepresented3,4.

By avoiding the need for direct experimentation and observation, genetic techniques have allowed us to represent the Tree of Life in a much more accurate way. Particularly, molecular methods allow us to build trees using sequenced markers, such as the small subunit ribosomal RNA gene.

The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much diversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are often only found in a single specimen5. A recent analysis of all genomes has produced an unfinished draft of a Tree of Life. This includes a large number of bacteria, archaea and other organisms that have not yet been isolated, or the diversity of which is not well understood6.

This expanded Tree of Life can be used to evaluate 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 new medicines to combating disease to improving crops. The information is also incredibly valuable for conservation efforts. It can help biologists identify areas that are likely to have species that are cryptic, which could perform important metabolic functions and are susceptible to human-induced change. While funds to protect biodiversity are important, the most effective way to conserve the world's biodiversity is to equip more people in developing nations with the information they require to act locally and promote conservation.

Phylogeny

A phylogeny, also known as an evolutionary tree, illustrates the connections between various groups of organisms. Utilizing molecular data, morphological similarities and differences, or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms that have similar characteristics and have evolved from a common ancestor. These shared traits can be either homologous or analogous. Homologous characteristics are identical in terms of their evolutionary journey. Analogous traits could appear like they are but they don't have the same origins. Scientists group similar traits into a grouping referred to as a the clade. All members of a clade have a common trait, such as amniotic egg production. They all came from an ancestor with these eggs. A phylogenetic tree is built by connecting the clades to determine the organisms that are most closely related to one another.

Scientists make use of DNA or RNA molecular information to construct a phylogenetic graph that is more accurate and precise. This information is more precise and gives evidence of the evolution of an organism. Molecular data allows researchers to identify the number of species that have an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships of a species can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is a kind of behaviour that can change due to particular environmental conditions. This can cause a particular trait to appear more similar in one species than another, clouding the phylogenetic signal. However, this issue can be solved through the use of techniques like cladistics, which include a mix of homologous and analogous features into the tree.

In addition, phylogenetics can help predict the length and speed of speciation. This information can aid conservation biologists to make decisions about which species they should protect from extinction. In the end, it's the conservation of phylogenetic variety that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The main idea behind evolution is that organisms acquire various characteristics over time due to their interactions with their environments. A variety of theories about evolution have been developed by a wide variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve gradually according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that can be passed on to offspring.

In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection and particulate inheritance -- came together to form the modern evolutionary theory which explains how evolution is triggered by the variations of genes within a population, and how those variations change over time due to natural selection. This model, called genetic drift, mutation, gene flow, and sexual selection, is the foundation of the current evolutionary biology and is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species by mutation, genetic drift and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of a 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 over time (the expression of that genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny and evolutionary. A recent study conducted 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 class. For more details about how to teach evolution look up 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 looking back, studying fossils, comparing species, and studying living organisms. Evolution isn't a flims event, but a process that continues today. Bacteria transform and resist antibiotics, viruses reinvent themselves and elude new medications, and animals adapt their behavior to a changing planet. The results are usually easy to see.

However, it wasn't until late 1980s that biologists realized that natural selection could be observed in action as well. The key is the fact that different traits can confer the ability to survive at different rates as well as reproduction, and may be passed on from generation to generation.

In the past, when one particular allele--the genetic sequence that determines coloration--appeared in a population of interbreeding species, it could quickly become more prevalent than all other alleles. Over time, that would mean the number of black moths within a population 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 evolutionary change when an organism, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from one strain. Samples from each population have been taken regularly, and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's research has shown that mutations can drastically alter the efficiency with which a population reproduces and, consequently, the rate at which it evolves. It also shows that evolution takes time--a fact that many find difficult to accept.

Another example of microevolution is the way mosquito genes that confer resistance to pesticides appear more frequently in areas where insecticides are used. Pesticides create a selective pressure which favors those who have resistant genotypes.

The rapidity of evolution has led to an increasing recognition of its importance especially in a planet which is largely shaped by human activities. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding evolution can help you make better decisions about the future of the planet and its inhabitants.