Evolution - Historical Background, The Modern Synthesis, Evidence Of Evolution, Evolutionary Mechanisms, Species Diversity And Speciation
change biological organisms genetic
Evolution refers to biological change. Biological evolution involves change in the genetic constitution of populations over time such that complexity is achieved due to the formation of new genes or gene-encoded functions rather than harmful mutations. These changes are passed on from parents to their offspring, but biological evolution does not involve individual organisms. Individuals develop, but they do not evolve. The study of evolution encompasses two major facets: deducing the history of descent among living things (phylogenetic systematics), and investigating evolutionary mechanisms as revealed by laboratory and field studies of living organisms and their fossilized remains. Evolutionary change occurs as a result of beneficial mutation, migration, genetic drift and natural selection, and it is ultimately a passive process, devoid of any purpose or goal. As a scientific theory, it is an interconnected series of hypotheses, corroborated by a large body of evidence. Thus, biologists accept the historical reality of evolution, even though many details that are unclear continue to be investigated.
Additional Topics
The birth of modern evolutionary theory can be traced to the mid-nineteenth century, and the publication of Charles Darwin's book, The Origin of Species by Means of Natural Selection in 1859. The book is considered by some to be the most influential in all of biology and by others an unsubstantiated theory. It was not, however, a new concept. Even in the late eighteenth century, the French …
By the 1920s, Mendel's theory of heredity had been rediscovered, but the early Mendelians, such as William Bateson and Hugo de Vries, opposed Darwin's theory of gradual evolutionary change. These geneticists favored the position that evolution proceeds in large jumps, or macro-mutations, rather than the gradual, incremental changes proposed by Darwin. The dispute between the Mendelia…
Darwin recognized that some of the best evidence of evolution remains hidden within the bodies of living creatures. He reasoned that, if organisms have a history, then their history can be deciphered from their remnants. In fact, virtually all living creatures possess vestigial or rudimentary features that were once functional traits of their ancestors. Fetal whales, still in their mothers'…
To an evolutionary biologist, evolution is a change in the proportion of genes present in an existing population. Each individual in a breeding population possesses a unique genotype, the set of paired genetic alternatives that determines its physical attributes, or phenotype. According to a principle known as the Hardy-Weinberg equilibrium, if certain conditions prevail, the frequency of each gen…
Biologists have estimated that there are as many as 50 million species living on Earth today. Remarkably, it is believed that this figure is only 1% of the species that have ever lived. The great diversity of organisms, living and extinct, is the result of speciation, the splitting and divergence of biological lineages to create new species. The term "species" is derived from the Lat…
The process of classifying and reconstructing the evolutionary history, or phylogeny, of organisms is known as phylogenetic systematics. Its goal is to group species in ways that reflect a common ancestry. The members of each group, or taxon, share uniquely derived characteristics that have arisen only once. For instance, the taxon Amniota includes amphibians, reptiles, birds and mammals, all of w…
Citing this material
Please include a link to this page if you have found this material useful for research or writing a related article. Content on this website is from high-quality, licensed material originally published in print form. You can always be sure you're reading unbiased, factual, and accurate information.
Highlight the text below, right-click, and select “copy”. Paste the link into your website, email, or any other HTML document.
User Comments