"If the cooling and drying stressed individual species to the point where they went extinct over parts of their range and only survived in areas that were optimal, a mechanism for allopatric speciation emerges.
Each of the models of allopatric speciation is probably relevant to a different degree for the speciation process in different faunal groups or during different geological periods.
Can local interactions influence regional processes which affect the potential for population differentiation and thus allopatric speciation? A number of authors have argued that the primary force preventing population differentiation that would lead to allopatric speciation is the similarity in selection pressures experienced by different populations across the range of a species (e.g., Ehrlich and Raven 1969, Lande 1980).
This difference in selection regimes between the two regions of the species range should therefore be conducive to generating allopatric speciation (Rice and Hostert 1993).
Thus, the species that are most likely to demonstrate speciation by distance around a ring are also the species that are most susceptable to geographic or allopatric speciation
, leading in most cases to uncertainty about the ultimate cause of reproductive isolation.
The author pulls no punches about his own position, stating clearly at the outset that "This book is written about the two most common forms of speciation in bisexual plants and animals, the non-chromosomal forms of allopatric speciation and the processes of chromosomal speciation" (p.
King stresses that there has been an overemphasis on allopatric speciation at the expense of the vast amount of new data supporting one or more chromosomal speciation hypotheses.
Secondary zones have been identified by multiple concordant clines (including those for presumably neutral markers), and the prevalence of such concordance is one of the traditional arguments for the ubiquity of allopatric speciation
Although evidence for these heroic journeys is scant, Mayr (1963) concluded that allopatric speciation
rarely occurs in freshwater plankton.
A model for divergent, allopatric speciation
of polyploid pteridophytes resulting from silencing of duplicate-gene expression.
. 1980, Genetic variation and phenotypic evolution during allopatric speciation
. American Naturalist 116:463-479.
The view that allopatric speciation
is the predominant mode of speciation in animals seems firmly established (Mayr 1942, 1963).