Causes of rarity

Abstract

Several possible causes of rarity have been touched on in preceding chapters (historical factors in Chapters 2 and 5 and environmental factors in Chapter 3). In this chapter, both these and other possibilities are considered in some detail.

Who can explain why one species ranges widely and is very numerous, and why another allied species has a narrow range and is rare? C. Darwin (1859)

The causes of rarity are to be found by identifying the constraints on the potential rate at which the population size of the selected species can increase. J. Greig-Smith and G. R. Sagar (1981)

It is time to sort out the recent potential causes of rarity, such as fire suppression, direct habitat alteration, increased herbivore populations, or horticultural fancy from the evolutionary consequences of vicariance, genetic depletion, taxon age, aberrant chromosomal events, or possible evolutionary consequences of human intervention. P. L. Fiedler(1986)

The list of examples where rare species could lead to erroneous conclusions is limited only by the imagination of the reader. M. A. Buzas et al. (1982)