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Plant Species Disjunctions: A Summary

1972; Missouri Botanical Garden; Volume: 59; Issue: 2 Linguagem: Inglês

10.2307/2394756

2162-4372

Peter H. Raven,

Genetic diversity and population structure

Disjunctions in the ranges of plant species have fascinated biologists ever since they were first detected; their interpretation has long been regarded as one of the central problems of plant geography. It seems intuitively reasonable that following its origin, a species should migrate to occupy a more or less continuous range; but when we find it occupying two or more areas separated by hundreds or even thousands of miles, we wonder how this pattern could possibly have originated. If the disjunction is expressed at a higher level-for instance, generic or familialthe problem remains the same, but its solution may be even more difficult. Other papers in this symposium have touched on the major classes of disjunctions which have concerned biologists in the past. Before reviewing these, it is appropriate first to consider some general points that pertain to the study of all disjunctions and to consider some of the new and important kinds of evidence that have been brought into play in recent years.