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Chapter 24
The Origin of Species - Campbell & Reece 8th Ed.
19
Biology
Undergraduate 2
04/07/2010

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Term
Speciation
Definition
An evolutionary process in which one species splits into two or more species.
Term
Microevolution
Definition
Evolutionary change below the species level; change in the allele frequencies in population over generations.
Term
Macroevolution
Definition
evolutionary change above the species level, including the origin of a new group of organisms or a shift in the broad pattern of evolutionary change over a long period of time. Examples of macroevolutionary change include the appearance of major new features of organisms and the impact of mass extinctions on he diversity of life and its subsequent recover.
Term
Biological Species Concept
Definition
Definition of a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable, fertile offspring with members of other such groups.
Term
Reproductive Isolation
Definition
The existence of biological factors (barriers) that impede members of two species from producing viable fertile offspring.
Term
Hybrid
Definition
Offspring that results from the mating of individuals from two different species or two true-breeding varieties of the same species.
Term
Prezygotic Barriers
Definition
A reproductive barrier that impedes mating between species or hinders fertilization if interspecific mating is attempted.
Term
Postzygotic Barriers
Definition
A reproductive barrier that prevents hybrid zygotes produced by two different species from developing into viable, fertile adults.
Term
Morphological Species Concept
Definition
A definition of species in terms of measurable anatomical criteria.
Term
Ecological Species Concept
Definition
A definition of species in terms of ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment.
Term
Phylogentic Species Concept
Definition
A definition of species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.
Term
Allopatric speciation
Definition
The formation of new species in populations that are geographically isolated from one another.
Term
Sypatric Speciation
Definition
The formation of new species in populations that live in the same geographic area.
Term
Polyploidy
Definition
A chromosomal alteration in which the organism possesses more than two complete chromosome sets. It is the result of an accident of cell division.
Term
Autopolyploid
Definition
An individual that has more than two chromosome sets that are all derived from a single species.
Term
Allopolyploid
Definition
A fertile individual that has more than two chromosome sets as a result of two different species interbreeding and combing their chromosomes.
Term
Hybrid Zone
Definition
A geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry.
Term
Reinforcement
Definition
A process in which natural selection strengthens prezygotic barriers to reproduction, thus reducing the chances of hybrid formation. such a process is likely to occur only in hybrid offspring are less fit than members of the parent species.
Term
Punctuated Equilibria
Definition
In the fossil record, long periods of apparent stasis, in which a species undergoes little or no morphological change, interrupted by relatively brief periods of sudden change.
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