The Development of Evolutionary Theory
Natural selection- the most critical mechanism of evolutionary change, first described
by Charles Darwin; refers to genetic change or changes in the frequencies of certain
traits in populations due to differences in reproductive success between individuals.
Fixity of species- the notion that species, once created, can never change; an idea
diametrically opposed to theories of biological evolution.
Copernicus is generally credited with removing the earth as the center of all things, and
in the early 1600s, Galileo restated Copernicus’ views in print, using logic and
mathematics to support his claim.
The seventeenth century saw the discovery of the principles of physics (such as motion
and gravity) and numerous specific instruments, including the microscope were
John Ray- developed the concept of species and was the first to use the labels genus
Reproductively isolated- pertaining to groups of organisms that, mainly because of
genetic differences, are prevented from mating and producing offspring with members of
Carolus Linnaeus- developed a method of classifying plants and animals. In his
famous work, Systema Naturae (Systems of Nature), he standardized Ray’s use of
genus and species terminology and established the system of binomial nomenclature.
He also added two more categories: class and order. Linnaeus’ four-level system
became the basis for taxonomy.
Binomial nomenclature- “two names” in taxonomy, the convention estab. by Linnaeus
whereby genus and species names are used to refer to species.
Taxonomy- the branch of science concerned with the rules of classifying organisms on
the basis of evolutionary relationships.
Georges-Louis Leclerc de Buffon- recognized the dynamic relationship between the
external environment and living forms. In his Natural History, he recognized that
different regions have unique plans and animals. He also stressed that animals had
come from a “center of origin.” He recognized that alterations of the external
environment, including the climate, were agents of change in species. The father of
Jean-Baptiste Lamarck- tried to explain the evolutionary process. He suggested a
dynamic relationship between species and the environment such that if the external
environment changed, an animal’s activity patterns would also change to accommodate 2
the new circumstances. His theory called the inheritance of acquired characteristics or
the use-disuse theory stated that the parts of animals that weren’t used would disappear
over time. However, the parts that continued to be used would change over time. So,
physical changes would occur in response to bodily “needs.”
Georges Cuvier- introduced the concept of extinc