However, we do not exclude the possibility that individual dispersal events have occurred, but after vicariant events
The consensus cladogram shows a sequence of vicariant events
from North to South.
The parameters varied in the model's gene flow regimes under isolation by distance and the timing of vicariant events
in sundered populations.
Consider now effects of a vicariant event
that interrupts gene flow at one point in the cline, but that leaves all populations on either side of this point still exchanging migrants.
These divergence date estimates are at least in part consistent with Haffer's (Haffer 1969; Simpson and Haffer 1978) hypothesis that most geographically differentiated species are the result of Pleistocene climatic vicariant events
, although probably not the most recent cycle of glaciation (21,000-13,000 ybp; van der Hammen 1974).
For example, if two widespread species were fragmented by a vicariant event
, one would eventually expect that haplotypes in each species would be monophyletic on each side of the isolating barrier.
aculeatus suggests an old age for the vicariant event
separating the major clades.
However, from figure 4 it is unclear whether the allozymic differences found between croceater and klauberi reflect lack of information about "Bob's Gap" or an older vicariant event
Of course, vicariance events could isolate small peripheral populations, but this would seem infrequent; by chance, a vicariant event
should have a greater probability of occurring within the center of a species' range (unless the peripheral populations exist in ecological margins).
distribution is inferred to be wide (= sum of all areas, ABcDEFG) with the occurrence of subsequent vicariant events
These subregions suggest specific microhabitats for the benthic hydroid fauna of the SO that may be derived from dispersal or vicariant events
The primary aim of many historical and evolutionary studies of marine species is to ascertain oceanographic conditions, climatic factors, and vicariant events
disrupting gene flow and genetic diversity, in relation to biogeographic patterns of demographic expansion and contraction.