watertonense was higher than B^ paradoxum in one year but lower 

 than B_^ hesperium in the two other years (Fig. 4) . 



DISCUSSION 



We have obtained no evidence that would indicate that 

 Botrvchium paradoxum and B^ watertonense are anything but 

 morphologically stable species. 



The shape of the depletion curves for all three species 

 suggests that they are short-lived perennials. However, it 

 should be kept in mind that plants may exist underground as 

 gametophytes for a period of time before emeriging as a mature 

 sporophyte. Nonetheless, compared to Botrychium dissectum, all 

 three species are short lived (Montgomery 1990) . The high rates 

 of mortality and recruitment demonstrated by these three species 

 of Botrychium suggest that they are adapted to occupying early 

 successional sites or ephemeral gaps in more stable vegetation 

 (MacArthur and Wilson 1967, Harper 1977, Solbrig and Solbrig 

 1979) • Botrychium paradoxum has the highest rates of mortality 

 and recruitment, indicating that it has the most volatile 

 demographic regime and suggest that of all three species, it is 

 the most adapted to ephemeral habitats and is the most prone to 

 cycles of extinction and recolonization (Diamond 1984, Pimm et 

 al. 1988) . 



Botrvchium hesperium is longer lived and had lower levels 

 of recruitment and mortality for all years measured compared to 

 B. paradoxum . These differences in life history must be at least 

 partially genetically determined since the two populations are 

 growing in the same environment. Hybridization may result in 

 the breakup or restructuring of coadapted gene complexes, and 

 breakup of integrated genetic systems often results in increased 

 additive genetic variation (Carson 1975, Templeton 1980) . 

 Morphological and chemical evidence indicates that B. 

 watertonense is a hybrid between these two species (Wagner et al. 

 1984) . The life history characteristics of the hybrid plants are 

 more variable and encompass more than the range of either of the 

 putative parent species. Our results provide evidence that 

 balanced genetic systems interacting with environment to produce 

 life history traits in the parent Botrychium species have been 

 disrupted in the hybrid. 



