Reproductive behavior of female buntings: Isolating mechanisms
in a hybridizing pair of species.
The reputation of the organization, another potential isolating mechanism, can be thought of as the net effect of positive and negative perceptions regarding the organization at any one time.
We tested our hypotheses using hierarchical regression analysis where we first entered the three control variables (Model 1), followed by the two "superior knowledge" predictors (Model 2), and, finally, the three "isolating mechanism" predictors (Model 3).
(3) The Trust created a new strategic isolating mechanism
and new institutional rules of play, since access to film stock and equipment now required membership in or licensing by the Trust.
Thus, the effect of differential pollen-tube growth on hybridization frequency that we have demonstrated with controlled crosses has the opportunity to act as a heterospecific isolating mechanism
Although the importance of reproductive isolation in the formation and maintenance of species has been widely accepted (Mayr 1942; Dobzhansky 1951; Littlejohn 1981; Futuyma 1986; Endler 1989; Ridley 1993; but see Paterson 1985), elucidating the genetics and transformation of specific reproductive isolating mechanisms
remains a formidable challenge for evolutionary biologists (Coyne and Orr 1989a,b; Endler 1989; Coyne 1993).
Given these conditions, the likely premating isolating mechanism
remains the timing differences in cercarial shedding, diurnal for S.
Besides the original definition, Dobzhansky's major contribution to this notion is his classification of the biological factors preventing hybridization, the so-called "reproductive isolating mechanisms
," and their division into categories acting before (prezygotic) and after (postzygotic) fertilization.
In a 50-minute lecture period I introduce species concepts (at least the biological and morphological species concepts), the reproductive isolating mechanisms
that keep species distinct, and modes of speciation (allopatric and sympatric).
A sampling of topics includes evaluating enterprise integration middleware technologies; improving architectural composability and consumability using communities; isolating mechanisms
in COTS-based systems; and reconfiguring workflows of Web services.
The article says that Mayr focuses solely on geographic separation, "allopathic speciation." This ignores the fact that Mayr discussed a variety of other isolating mechanisms
besides allopathic speciation.
An explanation for this pattern may lie in the relative strength of prepollination and postpollination isolating mechanisms
. Iris fulva and I.