The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those who are interested in science understand evolution theory and how it is permeated in all areas of scientific research.

This site offers a variety of sources for teachers, students as well as general readers about evolution. It contains key video clips from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of life. It appears in many spiritual traditions and 에볼루션 무료 바카라 cultures as an emblem of unity and love. It has numerous practical applications as well, such as providing a framework to understand the history of species, and how they react to changes in environmental conditions.

Early approaches to depicting the world of biology focused on categorizing organisms into distinct categories which had been distinguished by physical and 에볼루션사이트 metabolic characteristics1. These methods are based on the sampling of different parts of organisms or short DNA fragments have greatly increased the diversity of a Tree of Life2. However the trees are mostly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

By avoiding the necessity for direct experimentation and 에볼루션 룰렛 observation genetic techniques have allowed us to depict the Tree of Life in a more precise way. We can construct trees using molecular methods, such as the small-subunit ribosomal gene.

Despite the massive growth of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is particularly true for microorganisms, which are difficult to cultivate and are usually only present in a single sample5. A recent analysis of all genomes that are known has produced a rough draft version of the Tree of Life, including a large number of bacteria and archaea that are not isolated and their diversity is not fully understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, assisting to determine if 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 the quality of crops. This information is also beneficial for conservation efforts. It can help biologists identify the areas most likely to contain cryptic species with significant metabolic functions that could be at risk from anthropogenic change. While conservation funds are important, the most effective method to preserve the world's biodiversity is to empower more people in developing nations with the information they require to act locally and support conservation.

Phylogeny


Evolutionary Theory

The fundamental concept of evolution is that organisms develop different features over time based on their interactions with their environments. Many theories of evolution 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 slowly in accordance with its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that could be passed onto offspring.

In the 1930s & 1940s, ideas from different areas, 에볼루션 무료 바카라 including natural selection, genetics & particulate inheritance, merged to form a modern evolutionary theory. This describes how evolution is triggered by the variation of genes in the population, and how these variants change with time due to natural selection. This model, known as genetic drift, 에볼루션 무료체험 mutation, gene flow and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically explained.

Recent developments in the field of evolutionary developmental biology have shown that variation can be introduced into a species via mutation, 에볼루션 무료 바카라 genetic drift, and reshuffling of genes in sexual reproduction, as well as through the movement of populations. These processes, in conjunction with others such as the directional selection process and the erosion of genes (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 an individual).

Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny and evolutionary. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence that supports evolution increased students' acceptance of evolution in a college biology course. To learn more about how to teach about evolution, see The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by studying fossils, comparing species and observing living organisms. But evolution isn't just something that occurred in the past. It's an ongoing process, taking place today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and elude new medications, and animals adapt their behavior in response to the changing environment. The changes that occur are often evident.

It wasn't until late 1980s when biologists began to realize that natural selection was at work. 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, if one particular allele - the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it could quickly become more common than the other alleles. As time passes, this could 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.

Observing evolutionary change in action is much easier when a species has a rapid generation turnover such as bacteria. Since 1988, 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 500.000 generations have passed.

Lenski's work has shown that mutations can alter the rate at which change occurs and the effectiveness of a population's reproduction. It also shows that evolution is slow-moving, a fact that some people find hard to accept.

Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides are used. This is because the use of pesticides creates a pressure that favors individuals with resistant genotypes.

The speed of evolution taking place has led to an increasing recognition of its importance in a world that is shaped by human activities, including climate change, pollution and the loss of habitats that prevent many species from adjusting. Understanding the evolution process can help us make smarter choices about the future of our planet and the life of its inhabitants.