So , You've Purchased Evolution Site ... Now What?

The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies have been for a long time involved in helping those interested in science comprehend the theory of evolution and how it permeates all areas of scientific research.

This site provides teachers, students and general readers with a variety of educational resources on evolution. It contains the most important video clips from NOVA and WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is an emblem of love and unity across many cultures. It has many practical applications as well, such as providing a framework to understand the history of species, and how they respond to changes in environmental conditions.

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 depend on the collection of various parts of organisms or fragments of DNA have greatly increased the diversity of a tree of Life2. However, these trees are largely made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have enabled us to represent the Tree of Life in a more precise way. We can construct trees using molecular methods like the small-subunit ribosomal gene.

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

The expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if specific habitats need special protection. This information can be utilized in a variety of ways, including identifying new drugs, combating diseases and enhancing crops. This information is also valuable in conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species with significant metabolic functions that could be at risk from anthropogenic change. Although funding to protect biodiversity are essential but the most effective way to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, shows the connections between various groups of organisms. By using molecular information as well as morphological similarities and distinctions, or ontogeny (the process of the development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolution of taxonomic categories. Phylogeny is crucial in understanding evolution, biodiversity and genetics.

에볼루션  (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that have evolved from common ancestors. These shared traits could be either analogous or homologous. Homologous traits are the same in terms of their evolutionary path. Analogous traits might appear similar but they don't have the same ancestry. Scientists organize similar traits into a grouping referred to as a clade. For instance, all of the organisms that make up a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor that had these eggs. The clades then join to form a phylogenetic branch that can identify organisms that have the closest relationship to.

Scientists utilize molecular DNA or RNA data to construct a phylogenetic graph that is more precise and precise. This information is more precise than morphological information and provides evidence of the evolution history of an individual or group. Researchers can use Molecular Data to determine the evolutionary age of organisms and identify the number of organisms that have the same ancestor.

The phylogenetic relationships between organisms can be influenced by several factors, including phenotypic plasticity a kind of behavior that alters in response to unique environmental conditions. This can make a trait appear more similar to one species than another which can obscure the phylogenetic signal. This problem can be addressed by using cladistics, which is a a combination of homologous and analogous traits in the tree.

Additionally, phylogenetics aids determine the duration and rate at which speciation takes place. This information will assist conservation biologists in making choices about which species to safeguard from the threat of extinction. It is ultimately 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 due to 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 would evolve according to its individual needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can lead to changes that can be passed on to future generations.

In the 1930s and 1940s, ideas from various fields, including natural selection, genetics, and particulate inheritance--came together to create the modern synthesis of evolutionary theory, which defines how evolution occurs through the variation of genes within a population, and how those variations change in time due to natural selection. This model, which incorporates genetic drift, mutations in gene flow, and sexual selection can be mathematically described mathematically.

Recent discoveries in evolutionary developmental biology have revealed how variations can be introduced to a species via genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of a genotype over time) can lead to evolution, which is defined by changes in the genome of the species over time, and the change in phenotype over time (the expression of the 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 example revealed that teaching students about the evidence supporting evolution increased students' understanding of evolution in a college biology course. To find out more about how to teach about evolution, read The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species, and observing living organisms. However, evolution isn't something that happened in the past; it's an ongoing process taking place today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals change their behavior to the changing environment. The changes that result are often evident.

But it wasn't until the late 1980s that biologists realized that natural selection can be observed in action as well. The reason is that different traits have different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.

In the past, when 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. Over time, that would mean that the number of black moths in 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 track evolutionary change when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from one strain. The samples of each population have been taken frequently and more than 500.000 generations of E.coli have passed.

Lenski's research has shown that a mutation can profoundly alter the speed at the rate at which a population reproduces, and consequently, the rate at which it alters. It also demonstrates that evolution takes time--a fact that some find difficult to accept.

Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides have been used. This is due to pesticides causing a selective pressure which favors individuals who have resistant genotypes.

The speed of evolution taking place has led to a growing appreciation of its importance in a world that is shaped by human activity--including climate change, pollution, and the loss of habitats which prevent many species from adapting. Understanding the evolution process will help us make better choices about the future of our planet, and the life of its inhabitants.