Exam 2 Flashcards
Co-discoverer of natural selection?
Alfred Wallace
Wallace Effect?
natural selection contributes to speciation by promoting hybridization barrierss
Disjunct distributions?
when a taxon has 2 or more closely related groups that considerable separated from each other graphically
Allopatric speciation?
speciation by geographic isolation rivers, deserts or great distances
- often isolated in different environments
How does allopatric speciation occur?
occurs due to both adaption and genetic drift
Peripatric speciation?
- Special case of allopatric speciation
- small fraction of population isolated
- few isolated individuals carry rare alleles
How does peripatric speciation occur?
Genetic drift
Parapatric speciation?
- along environmental gradient
- individuals at ends adapted to fringe environments
- typically among species with limited dispersal
How does parapatric speciation occur?
mostly by adaptation to gradient
Sympatric Speciation?
-individuals occupy same geographic area, but still become reproductively isolated
How does sympatric speciation occur?
strong selection–> Adaptation
Dispersal?
taxa migrate from one region to another and establish new populations
- peripatric or allopatric
Vicariance?
Distribution becomes disjunct by the development of geographic barriers
Continental drift
- Proposed by Alfred Wegener
- Land masses seem to fit together, continental part of lithospheric plates float on basaltic crust on top of mountains
the likely principle direct or indirect source of vicariate events?
Contiental drift
Most important factor regulating fish distributions?
temperature
4 Major marine zoogeographic regions?
- Indo-West Pacific
- Western Atlantic
- Eastern Pacific
- Eastern Atlantic
Geminate species?
sister species from common ancestors whose distributions interrupted by rise of Panamanian isthmus
Primary Freshwater fishes?
confined to fresh water, evolutionary history in FW, no tolerance to high salinities
How many families of primary FW fishes?
85 families
Secondary FW fishes?
restricted to FW, may occasionally enter saltier waters
How many families of secondary FW fishes?
11 families
Peripheral FW fishes?
marine species with residence, that spend portion of life cycle in FW (i.e..e diadromous)
How many families of peripheral FW fishes?
30 families