The Academy's Evolution Site

Biology is one of the most central concepts in biology. The Academies have long been involved in helping people who are interested in science comprehend the concept of evolution and how it permeates all areas of scientific exploration.

This site provides teachers, students and general readers with a variety of learning resources about evolution. It contains key 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 seen in a variety of cultures and spiritual beliefs as a symbol of unity and love. It can be used in many practical ways as well, such as providing a framework for understanding the evolution of species and how they react to changing environmental conditions.

Early attempts to describe the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely on the sampling of various parts of living organisms or on sequences of small fragments of their DNA, greatly increased the variety of organisms that could be represented in the tree of life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4.

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

Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are often only present in a single sample5. A recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a wide range of archaea, bacteria, and other organisms that have not yet been identified or the diversity of which is not well understood6.

This expanded Tree of Life can be used to determine the diversity of a specific area and determine if certain habitats require special protection. This information can be used in a variety of ways, including finding new drugs, battling diseases and improving crops. It is also beneficial to conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which may have vital metabolic functions and are susceptible to changes caused by humans. Although funding to safeguard biodiversity are vital however, the most effective method to preserve the world's biodiversity is for more people living in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny is also known as an evolutionary tree, reveals the relationships between various groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic groups using molecular data and morphological similarities or differences. 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 that share similar traits that evolved from common ancestral. These shared traits could be either homologous or analogous. Homologous characteristics are identical in terms of their evolutionary path. Analogous traits may look similar, but they do not have the same origins. Scientists organize similar traits into a grouping known as a clade. Every organism in a group have a common characteristic, like amniotic egg production. They all derived from an ancestor who had these eggs. A phylogenetic tree is then constructed by connecting clades to determine the organisms who are the closest to one another.

Scientists make use of molecular DNA or RNA data to construct a phylogenetic graph that is more precise and detailed. This data is more precise than morphological data and gives evidence of the evolutionary background of an organism or group. Researchers can utilize Molecular Data to determine the age of evolution of organisms and identify 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 specific environmental conditions. This can cause a characteristic to appear more like a species other species, which can obscure the phylogenetic signal. This issue can be cured by using cladistics. This is a method that incorporates a combination of homologous and analogous traits in the tree.

Furthermore, phylogenetics may aid in predicting the length and speed of speciation. This information will assist conservation biologists in deciding which species to protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their environments. A variety of theories about evolution have been developed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that could be passed onto offspring.

In the 1930s and 1940s, concepts from various fields, such as genetics, natural selection and particulate inheritance, came together to form a contemporary theorizing of evolution. This describes how evolution occurs by the variation in genes within the population and how these variants alter over time due to natural selection. This model, which is known as genetic drift, mutation, gene flow, and sexual selection, 에볼루션 블랙잭 is a cornerstone of modern evolutionary biology and is mathematically described.

Recent developments in the field of evolutionary developmental biology have shown that variations can be introduced into a species through genetic drift, mutation, and reshuffling of genes during sexual reproduction, as well as through the movement of populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time) can lead to evolution which is defined by change in the genome of the species over time and also by changes in phenotype as time passes (the expression of that genotype in an individual).

Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny and evolution. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution increased students' acceptance of evolution in a college biology class. For more details on how to teach about evolution look up The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have studied evolution by looking in the past, analyzing fossils and comparing species. They also study living organisms. Evolution is not a past event, but an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, viruses reinvent themselves and elude new medications and animals change their behavior to the changing environment. The results are often evident.

However, it wasn't until late 1980s that biologists understood that natural selection could be seen in action, as well. The key 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 determines coloration--appeared in a population of interbreeding organisms, it might quickly become more prevalent than all other alleles. Over time, that would mean the number of black moths within a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to track evolution when the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. Samples of 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 revealed that a mutation can profoundly alter the efficiency with the rate at which a population reproduces, and consequently, the rate at which it evolves. It also shows evolution takes time, a fact that is difficult for some to accept.

Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations where insecticides have been used. Pesticides create an exclusive pressure that favors those who have resistant genotypes.

The rapid pace at which evolution takes place has led to an increasing recognition of its importance in a world that is shaped by human activity, including climate change, pollution, and the loss of habitats that hinder the species from adapting. Understanding evolution can aid you in making better decisions about the future of our planet and its inhabitants.