THE BIOLOGY OF RARITY - PATTERNS, CAUSES AND CONSEQUENCES

There is a growing body of evidence suggesting that locally rare and g eographically restricted species may have characteristics that differ from those of taxa that are more common. Several studies show that rar e taxa have lower levels of self-incompatibility, a tendency toward as exual reproductive pathways, lower overall reproductive effort and poo rer dispersal abilities. There are several mechanisms that could be re sponsible for such differences, but they may in practice be difficult to differentiate. Nonetheless, the documentation of recurrent rare-com mon differences is of vital importance because it may allow us to comp ensate partially for the bias of the published literature toward studi es of common taxa.