The role of drought tolerance in serpentine tolerance in the Mimulus guttatus Fischer ex DC. complex
Year: 2001
Type: article
Abstract: Two species in the Mimulus guttatus Fischer ex DC. complex are endemic to ultramafic (serpentine) soils: M. nudatus Curran, restricted to a small area in the coastal mountains, and M. pardalis Pennell, restricted to Sierran ultramafics in central California. It is likely that they originated from independent evolutionary events. While M. guttatus sensu stricto is a bodenvag species, found both on ultramafic and normal soils, there are other species in the complex that are apparently excluded from serpentine, including M. nasutus Greene and M. marmoratus Greene. Field observations suggest that response to drought is a major factor in determining Mimulus species distribution and thus possibly the evolution of the two endemics. We compared these five species for their physiological responses to drought. All species were very drought sensitive, and few differences were found among them. However, significant differences were found in the pressure/volume curves, suggesting that the endemics are more drought tolerant. From crosses between M. pardalis (serpentine endemic) and M. marmoratus (excluded from serpentine) a set of recombinant inbred (RI) lines were isolated. The RI lines were characterized for their tolerance to serpentine and drought; there was a significant positive correlation between drought and serpentine tolerance. The nickel tolerance of the RI lines was not correlated with their serpentine tolerance. Our results support the hypothesis that drought is the main driving force in the evolution of serpentine tolerance in this group of species.
Source: South African Journal of Science
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: diamond
OpenAlex ID: W2185885407