Chapter 2 Flashcards
**evolutionary theory
The set of testable hypotheses that assert that living organisms can change over time and give rise to new kinds of organisms, with the result that all organisms ultimately share a common ancestry.
**evolution
The process of change over time.
**essentialism
The belief, derived from Plato, in fixed ideas, or forms, that exist perfect and unchanging in eternity. Actual objects in the temporal world, such as cows or horses, are seen as imperfect material realizations of the ideal form that defines their kind.
**Great Chain of Being
A comprehensive framework for interpreting the world, based on Aristotelian principles and elaborated during the Middle Ages, in which every kind of living organism was linked to every other kind in an enormous, divinely created chain. An organism differed from the kinds immediately above it and below it on the chain by the least possible degree.
taxonomy
A classification; in biology, the classification of various kinds of organisms.
genus
The level of the Linnaean taxonomy in which different species are grouped together on the basis of their similarities to one another.
species
(1) For Linnaeus, a Platonic natural kind defined in terms of its essence. (2) For modern biologists, a reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature.
**catastrophism
The notion that natural disasters, such as floods, are responsible for the extinction of species, which are then replaced by new species.
**uniformitarianism
The notion that an understanding of current processes can be used to reconstruct the past history of the earth, based on the assumption that the same gradual processes of erosion and uplift that change the earth’s surface today had also been at work in the past.
**transformational evolution
Also called Lamarckian evolution, it assumes essentialist species and a uniform environment. Each individual member of a species transforms itself to meet the challenges of a changed environment through the laws of use and disuse and the inheritance of acquired characters.
common origin
Darwin’s claim that similar living species must all have had a common ancestor.
**natural selection
A two-step, mechanistic explanation of how descent with modification takes place: (1) every generation, variant individuals are generated within a species due to genetic mutation and (2) those variant individuals best suited to the current environment survive and produce more offspring than other variants.
**variational evolution
The Darwinian theory of evolution, which assumes that variant members of a species respond differently to environmental challenges. Those variants that are more successful (“fitter”) survive and reproduce more offspring, who inherit the traits that made their parents fit.
fitness
A measure of an organism’s ability to compete in the struggle for existence. Those individuals whose variant traits better equip them to compete with other members of their species for limited resources are more likely to survive and reproduce than individuals who lack such traits
aptation
Any useful feature an organism has
adaptation
The shaping of any useful feature of an organism, regardless of its origin.
exaptation
The shaping of a useful feature of an organism by natural selection to perform one function and the later reshaping of it by different selection pressures to perform a new function.
