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Biology 1b (Vista S2006)
Chapter 24 (Biology 6ed - Campbell/Reece)
22
Biology
Undergraduate 3
02/10/2006

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Term
Macroevolution
Definition
Evolutionary change on a grand scale, encompassing the origin of new taxonomic groups, evolutionary trends, adaptive radiation and mass extinction
Term
Speciation
Definition
The origin of new species in evolution
Term
Biological Species Concept
Definition
Defines a species as a population or group of populations whose members have the potential to interbreed with one another in nature to produce viable, fertile offspring, but who cannot produce viable fertile offspring with members of other species..
Term
Prezygotic Barriers
Definition
Impede mating between species or hinder the fertilization of ova if mating is attempted. This can occur through:

* Habitat isolation
* Behavioral isolation
* Mechanical isolation (tab A doesn't fit into slot B)
* Temporal isolation (isolated by different breeding times or seasons)
* Gametic Isolation (gametes fail to form a viable zygote)
Term
Postzygotic Barriers
Definition
If a zygote is formed, postzygotic barriers usually prevent development into a viable, fertile adult. This can occur through:

* Reduced Hybrid Viability (offsprind do not live or are feeble)
* Reuced Hybrid Fertility
* Hybrid Breakdown (first generation is viable/fertile, but subsequent generations are not)
Term
Ecological Species Concept
Definition
Defines a species in terms of its ecological niche, or the set of environmental resources it uses. A species' niche depends on its unique adaptations to a particular role in a biological community
Term
Pluralistic Species Concept
Definition
The idea that there is no universal explanation for the cohesion of individuals that make up a species.
Term
Morphological Species Concept
Definition
Characterizes each species in terms of a unique set of structural features
Term
Genealogical Species Concept
Definition
Defines a species as a set of organisms with a unique genetic history.
Term
Sympatric Speciation
Definition
A small population becomes a new species without geographic separation from its parent population
Term
Allopatric Speciation
Definition
A population forms a new species after becoming geographicaly isolated from its parent species.
Term
Adaptive Radiation
Definition
The emergenc of numerous species from a common ancestor
Term
Polyploidy
Definition
A mutation in which the organism has more than two complete sets of chromosomes
Term
Autopolyploid
Definition
A type of polyploid species resulting from one species doubling its chromosome number to become tetraploid. This organism may self-fertilize or mate with other tetraploids.
Term
Allopolyploid
Definition
A common type of polyploid species resulting from two different species interbreeding and combining their chromosomes
Term
Punctuated Equilibrium
Definition
Concept that species diverge in spurts of rapid change, then change very little. Long periods of stasis punctuated by periods of speciation.
Term
Exaptations
Definition
Structures that evolve in one context, but become co-opted for another function
Term
Allometric Growth
Definition
The variation in the relative rates of growth of different parts of the body, this helps define body proportion.
Term
Heterochrony
Definition
Evolutionary change in the rate or timing of development. For example, a mutation in a regulatory gene causing growth of a feature to end sooner than it normally would.
Term
Paedomorphosis
Definition
Retaining juvenile features into adulthood
Term
Homeotic Genes
Definition
Determine placement and spatial organization of an organism's features.
Term
Species Selection
Definition
Theory maintaining that the species living the longest and generating the greatest number of species determines the direction of major evolutionary trends.
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