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30 Cards in this Set

  • Front
  • Back
"phyletic evolution"
1. progressive evolution of species
2. change in gene frequency in an entire population
3. Formation of "new" species from "old"
"branching evolution"
1. splitting of gene pool
2. forms a "clade" of one or more new species
adaptions within a population and single gene pool
evolutionary change above the species level
Reproductive Isolation
biological barriers that prevent members of two species from producing viable and fertile offspring
Prezygotic barriers
disallow successful union of sperm and egg
Postzygotic barriers
disallow development of hybrid zygote
Temporal Isolation
two species that breed at different times of the day or different seasons will not mate
Habitat Isolation
two species that occupy different habitats within the same area are unlikely to encounter each other
Behavioral Isolation
some species require elaborate courtship rituals
Mechanical Isolation
morphological differences between species can prevent mating
Gametic Isolation
not all eggs and sperm are created equal
Reduced hybrid viability
some hybrids are not as robust as either parent
Reduced hybrid fertility
even vigorous hybrids can be sterile
Hybrid breakdown
first generation of hybrids are OK, but the offspring of two hybrids are feeble or sterile
Allopatric speciation
1. population is divided into two or more geographically isolated subpopulations.
2. populations can no longer interbreed
3. speciation has occurred.
Sympatric speciation
Speciation takes place in geographically overlapping populations
Mechanism of Sympatric speciation
1. Allopolyploidy
2. Habitat differentation
3. Sexual selection
Adaptive Radiation
evolution of many diversely adapted species from a common ancestor upon introduction to a new environment
Rate of Speciation
1. Gradualism
2. Punctuated equilibrium
Gradualism (speciation)
species appear and disappear gradually and regularly over time
Punctuated equilibrium
long periods of apparent stasis punctuated by periods of sudden and dramatic change.

NOTE: supported by the fossil record
Evolution not goal oriented
not a single evolutionary event, but the accumulation of many smaller evolutionary events
Biological species concept
1. asexual reproduction
2. fossils
3. unknown reproduction
Other species concepts
1. Morpological
2. Phylogenic
3. Paleontological
4. Ecological
Presence of extra sets of chromosomes because of accidents in cell division
1. more than 2 sets
2. from one species
1. more than 2 sets
2. from multiple species
Evolutionary change in the timing or rate of developmental events
Allometric growth
proportioning that gives the body its specific form