Patterns of Descent with Modification Flashcards
species is latin for
“kind” or “appearance.”
Biological Species Concept
Members of the same species are reproductively compatible.
occurs when barriers prevent two populations from interbreeding – keeping their gene pools separate.
Reproductive isolation
occurs before fertilization can occur (no offspring are produced)
Prezygotic isolation
ccurs after members of two different species have mated and produced a zygote.
Postzygotic isolation
Occurs when two species mate at different times of year
Temporal Isolation
occurs when two species occupy different habitats
Ecological Isolation
Occurs when two species have different courtship behaviors
Behavioral Isolation
Occurs when physical differences prevent copulation/ pollination
Mechanical Isolation
Incompatibilities between egg and sperm prevent fertilization
Gametic Isolation
fertilized egg fails to develop past the early embryonic stages
HYBRID INVIABILITY
hybrids are sterile because gonads develop abnormally or there is abnormal segregation of chromosomes during meiosis
HYBRID STERILITY
F1 hybrids are normal, vigorous, and viable, but F2 contains many weak or sterile individuals
HYBRID Breakdown
Occurs when some members of a population become geographically separated from the other members thereby preventing gene flow.
Allopatric Speciation or Geographical Location
When small groups of individuals break off from the larger group and form a new species, this is called peripatric speciation
Peripatric Speciation
A species is spread out over a large geographic area.
Parapatric Speciation
Occurs when members of a population that initially occupy the same habitat within the same range diverge into two or more different species.
Sympatric Speciation
occurs when a mutation causes an organism to have multiple sets of chromosomes instead of the usual diploid number
Polyploidy
