Landscape structure and genetic variation in plants: empirical evidence

Abstract

Accumulating evidence from studies of a variety of morphological, aliozyme and DNA markers indicates that plants generally exhibit high levels of intraspecific genetic variation (see Venable, 1984; Hamrick and Godt, 1989; Clegg, 1990 for reviews). Furthermore, this variation is often not distributed randomly among individuals but, for species with a variety of ecologies, there is evidence of significant genetic structure at various spatial and organizational scales, for example among individuals within populations (e.g. Schmitt and Gamble, 1990), among subpopulations within a region (e.g. Linhart et al, 1981) and among populations across a species’ range (e.g. Li and Adams, 1989). Several studies have pointed to correlations between genetic variation and environmental patterns (e.g. Snaydon and Davies, 1976; Warwick and Black, 1986; Xie and Knowles, 1992). Despite this, it is only quite recently that investigations of genetic variation and genetic processes have been more formally incorporated into the synthetic discipline of landscape ecology (e.g. Manicacci et al., 1992; Fore, Hickey and Vankat, 1992). This chapter deals with the empirical evidence for the influence of landscape structure on genetic variation in plants and the distribution of this variation: genetic structure. Underlying genetic processes are also discussed.