Plant reproductive strategies under environmental stress
Caruso, Christina , Case, Andrea , Bailey, Maia .
Why do Lobelia females like it hot? Potential effects of environmental stress on the expression of male sterility.
In many gynodioecious species, high temperature and/or low precipitation are correlated with higher ratios of female to hermaphrodite plants within populations. If sex is determined by both nuclear and cytoplasmic genes, then these environmental stressors can affect the relative fitness of the sexes via two mechanisms. First, stress may increase seed production of females relative to hermaphrodites (reproductive compensation). Second, stress may reduce the relative pollen or seed fitness of hermaphrodites that carry more male fertility restorer alleles (cost of restoration). Although models suggest that the cost of male fertility restoration is the key determinant of variation in population sex ratios, much more is known about the effect of environmental stressors on compensation than on cost. Lobelia siphilitica is an excellent system for studying the effects of environmental stressors on population sex ratios for two reasons. First, females are more common in sites with higher annual mean temperatures. This correlation suggests that temperature affects the relative fitness of female and hermaphrodite L. siphilitica. Second, L. siphilitica is one of the few gynodioecious species where there is evidence for a cost of restoring male fertility. Hermaphrodite L. siphilitica that carry more nuclear male fertility restorer alleles have lower pollen viability. This reduction in pollen fitness should limit the spread of restorer alleles and thus increase the frequency of L. siphilitica females. We develop the hypothesis that annual mean temperature and female frequency are correlated in L. siphilitica because of genotype-by-environment effects on the cost of restoration. We predict that restorer alleles will have a larger negative effect on pollen viability when L. siphilitica is growing at higher temperatures. Such genotype by environment interactions could result in L. siphilitica populations becoming more female-biased in response to increasing global temperatures. More generally, we suggest that understanding the ecology and genetics of the cost of male fertility restoration is key for predicting the effects of environmental stress on reproductive strategies of gynodioecious species.
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1 - University Of Guelph, Department Of Integrative Biology, New Science Complex, 50 Stone Road East, GUELPH, ON, N1G 2W1, Canada
2 - Kent State University, Box 5190, 256 Cunningham Hall, Kent, OH, 44242-0001, USA
3 - Providence College, Department of Biology, 1 Cunningham Square, Providence, RI, 02918, USA
cost of male fertility restoration
cytoplasmic male sterility
Presentation Type: Symposium or Colloquium Presentation
Location: Westminster Room/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 9:55 AM