Selection does not necessarily play a major role in the evolution of (secondary) reproductive isolation.
However, the evolution of secondary reproductive isolation in diverging populations is speeded up considerably if it is driven by diversifying selection.
However, our understanding of β-sheet structure lags behind that of α-helices, largely because, until recently, there was no model system to study the β-sheet secondary structure in isolation.
When incipient species experience secondary contact, prezygotic isolation mechanisms can become enhanced as a result of selection against hybridization, a process termed reproductive character displacement [ 11- 13].
Involvement of the central nervous system by lymphoma can occur in the presence of systemic lymphoma involvement (secondary) or in isolation as a primary CNS neoplasm.
And it is completely fitting with the model that secondary mechanisms of isolation such as xenophobia or racism, should often be asymmetrical, and strongest on the side that expresses the recessive traits.
How much could the incompatibilities presented here contribute to speciation of the subspecies of A. lyrata in case of possible secondary contact after isolation of 140,000 generations is unclear.
In contrast to the analysis on transmission, we observe a positive association for the number of secondary cases with isolation of influenza (Incidence Risk Ratio (IRR) = 2.11 (0.992, 4.49), p = 0.052).
Ahern et al. hypothesize that isolation secondary to stigma further contributes to poor physical and mental health, demonstrated most vividly in a refusal to access healthcare, even when it was badly needed [ 30].
Another scenario is, however, possible, which is to a certain degree related to the Dobzhansky-Muller model in that it would involve multiple steps, but those would occur in sequence, and not independently: the secondary steps of isolation would target traits specific to the saeptated population which could quite possibly be the one having driven the saeptation, but not necessarily.
