Abstract
Reproductive isolating mechanisms, either premating or postmating, are the key to speciation; hence, they are among the most important biological properties of species (Mayr, 1970; Dobzhansky et al., 1977) or of sympatric individuals of different adaptive systems (Littlejohn, 1980). Yet, whereas their nature is quite well known, their mode of origin, particularly of premating as opposed to postmating mechanisms, still remains largely obscure and controversial. Two opposing theories have attempted to resolve the question regarding their origin: the sympatric and allopatrictheories (Mayr, 1970, pp. 325–330; Littlejohn, 1980). According to the sympatric theory, reproductive isolating mechanisms are directly selected when two incipient species become sympatric, due to hybrid inferiority in their overlap zone (Wallace, 1889; Fisher, 1930; Dobzhansky, 1940, 1951; V. Grant, 1971; Blair, 1974) [see Littlejohn (1980) for review and a critical discussion; for mathematical analysis see Sawyer and Hartl (1981)]. According to the allopatric theory, isolating mechanisms arise as incidental by-products of adaptive genetic divergence in allopatry (Darwin, 1859; Muller, 1942; Mayr, 1942; Patterson and Stone, 1952). Recent attempts to reconcile these two opposing theories have suggested that, while primary isolating mechanisms could develop before contact is encountered, they may be perfected and/or reinforced by a secondary isolating mechanism in sympatry (Levin, 1971, 1978, and references therein). Yet this reconciliation does not provide a clear distinction or direct proof of the actual origin of primary isolating mechanisms. Are they due to selection in sympatry or are they incidential by-products of adaptive differentiation in allopatry? Alternatively, do they arise because of direct selection in accordance with factors in the original abiotic and biotic allopatric environment?
Original language | English |
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Title of host publication | Evolutionary Biology |
Editors | Max K. Hecht, Bruce Wallace, Ghillean T. Prance |
Place of Publication | Boston, MA |
Publisher | Springer US |
Pages | 147-214 |
Number of pages | 68 |
Volume | 19 |
ISBN (Electronic) | 978-1-4615-6980-0 |
ISBN (Print) | 978-1-4615-6982-4 |
DOIs | |
State | Published - 1986 |