Data from: Physiological effects of temperature do not explain prevalence of females in populations of gynodioecious Lobelia siphilitica growing in warmer climates

PREMISE OF THE STUDY: Gynodioecy is a sexual polymorphism whereby female
and hermaphroditic plants co-occur within populations. In many
gynodioecious species, stressful abiotic environments are associated with
higher frequencies of females. This association suggests that abiotic
stress affects the relative fitness of females and hermaphrodites and,
thus, the maintenance of gynodioecy. METHODS:To test whether abiotic
stress affects the fitness of females and hermaphrodites, we grew
open-pollinated Lobelia siphilitica families in temperature regimes
characteristic of the southern portion of the species' range (where
females are common) and the northern portion of the range (where females
are rare). We measured physiological and phenological traits that are
indicative of heat stress, and fitness components of females and
hermaphrodites that could affect the maintenance of gynodioecy. KEY
RESULTS:Contrary to expectations if growth at high temperatures is
stressful, we found that the hot treatment increased leaf chlorophyll
content, decreased the percentage of plants that delayed flowering
initiation, and did not affect the quantum efficiency of photosystem II.
Growth at high temperatures did not affect the magnitude of the difference
in rosette size (a correlate of flower number) between females and
hermaphrodites, or the variance in pollen viability among hermaphrodites.
CONCLUSIONS:We found that growing-season temperatures typical of high
female L. siphilitica populations were not stressful and did not affect
either the fitness of females compared to hermaphrodites or variation in
fitness among hermaphrodites. Consequently, further research is necessary
to explain correlations between abiotic environmental factors and the
frequency of females in this and other gynodioecious species.