Dictionary of Evolutionary Nomenclature - Letter E

echinoderm: Echinoderms, whose name means "spiny skin," are a group of marine invertebrates that includes starfish, brittle stars, basket stars, sea cucumbers, sand dollars, sea urchins, and others. They live in environments from shallow coastal waters to deep-sea trenches, from the tropics to the poles.

ecological genetics: The study of evolution in action in nature, by a combination of field work and laboratory genetics.

ecological species concept: A concept of species, according to which a species is a set of organisms adapted to a particular, discrete set of resources (or "niche") in the environment. Compare with biological species concept, cladistic species concept, phenetic species concept, and recognition species concept.

ecosystem: A community of organisms interacting with a particular environment.

Eldredge, Niles: A paleontologist and evolutionary biologist with the American Museum of Natural History, Eldredge, together with Stephen Jay Gould, proposed the theory of punctuated equilibria, providing paleontologists with an explanation for the patterns which they find in the fossil record. He has written several books for a general audience, including Time Frames: The Evolution of Punctuated Equilibria and Life in the Balance: Humanity and the Biodiversity Crisis.

electrophoresis: The method of distinguishing entities according to their motility in an electric field. In evolutionary biology, it has been mainly used to distinguish different forms of proteins. The electrophoretic motility of a molecule is influenced by its size and electric charge.

embryo: An early stage of animal development that begins after division of the zygote (the earliest stage, in which joined egg and sperm have not yet divided).embryonic: Related to an embryo, or being in the state of an embryo.

embryology: scientific study of the earliest stages of growth and development inorganisms.

emigration: The movement of organisms out of an area.

Emlen, Stephen: A world authority on the social behavior of animals, particularly birds. Emlen's interests center on evolutionary or adaptive aspects of animal behavior. The goal of his research is to better understand the social interactions that occur between individuals, especially cooperation and conflict.

empirical: Determined by experimentation.

Endler, John: A zoologist and professor with interests in evolution and how it affects geographic variation. His current research focuses on guppies (Poeciliareticulata) in their natural habitat, and how visual signs and vision dictate their behavior.

enzyme: A protein that acts as a catalyst for chemical reactions.

Eocene: The second oldest of the five major epochs of the Tertiary period, from54 to 38 mya. It is often known for the rise of mammals.

epistasis: An interaction between the genes at two or more loci, such that the phenotype differs from at would be expected if the loci were expressed independently.

Erwin, Douglas: Dr. Erwin is a paleobiologist with the National Museum of Natural History in the Smithsonian Institution. His research is concerned with aspects of major evolutionary novelties, particularly the Metazoan radiation and post-mass extinction recoveries. Recent work has involved the developmental events associated with the Cambrian along with their environmental context. He also works on the rate, causes, and consequences of the end-Permian mass extinction.

eugenics: The science or practice of altering a population, especially of humans, by controlled breeding for desirable inherited characteristics. The term was coined in 1883 by Francis Galton, who was an advocate of "improving" the human race by modifying the fertility of different categories of people .Eugenics fell into disfavor after the perversion of its doctrines by the Nazis.

eukaryote: Any organism made up of eukaryotic cells. Eukaryotes are generally larger and have more DNA than prokaryotes (whose cells do not have a nucleus to contain their DNA). Almost all multicellular organisms are eukaryotes.

eukaryotic cell: A cell with a distinct nucleus.e

vo-devo: the informal name for 'evolutionary developmental biology', a branch of evolutionary studies that seeks to contribute insights from genetics, embryology and microbiology to help scientists better understand how new species arise from existing life forms

evolution: Darwin defined this term as "descent with modification." It is the change in a lineage of populations between generations. In general terms, biological evolution is the process of change by which new species develop from preexisting species over time; in genetic terms, evolution can be defined as any change in the frequency of alleles in populations of organisms from generation to generation.

evolutionary classification: Method of classification using both cladistic and phenetic classificatory principles. To be exact, it permits paraphyletic groups(which are allowed in phenetic but not in cladistic classification) and monophyletic groups (which are allowed in both cladistic and phonetic classification) but excludes polyphyletic groups (which are banned from cladistic classification but permitted in phenetic classification).

Ewald, Paul: Professor of biology at Amherst College, specializing in hummingbird and flower coevolution and the evolution of infectious diseases. His research on disease focuses on the evolutionary effects of various public health interventions.

exon: The nucleotide sequences of some genes consist of parts that code foramino acids, with other parts that do not code for amino acids interspersed among them. The coding parts, which are translated, are called exons; the interspersed non-coding parts are called introns.

extinction: The disappearance of a species or a population.