Size‐dependent sex allocation in Aconitum gymnandrum (Ranunculaceae): physiological basis and effects of maternal family and environment

Abstract

Theory predicts size-dependent sex allocation (SDS): flowers on plants with a high-resource status should have larger investment in females than plants with a low-resource status. Through a pot experiment with Aconitum gymnandrum (Ranunculaceae) in the field, we examined the relationship between sex allocation of individual flowers and plant size for different maternal families under different environmental conditions. We also determined the physiological base of variations in plant size. Our results support the prediction of SDS, and show that female-biased allocation with plant size is consistent under different environmental conditions. Negative correlations within families showed a plastic response of sex allocation to plant size. Negative genetic correlations between sex allocation and plant size at the family level indicate a genetic cause of the SDS pattern, although genetic correlation was influenced by environmental factors. Hence, the size-dependency of sex allocation in this species had both plastic and genetic causes. Furthermore, genotypes that grew large also had higher assimilation ability, thus showing a physiological basis for SDS.

Primary floral allocation per flower in 12 Pedicularis (Orobanchaceae) species: significant effect of two distinct rewarding types for pollinators

“…Species are coded as follows: A, P. cheilanthifolia; B, P. alaschanica; C, P. kansuensis; D, P. szetschuanica; E, P. curvituba; F, P. spicata; G, P. semitorta; H, P. chinensis; I, P. longiflora; J, P. cranolopha; K, P. armata; L, P. rhinanthoides primary floral allocation per flower and plant size at and above species level for our studied Pedicularis species. They are inconsistent with numerous previous studies (Klinkhamer et al 1997;Wright and Barrett 1999;Ashman et al 2001;Méndez and Traveset 2003;Zhao et al 2008) but in line with other studies (Mazer and Dawson 2001;Cao et al 2007;Guo et al 2010). Because of limited number of sampled species in each rewarding type in current study, we need to detect more extensive Pedicularis species to verify this pattern in future research.…”

“…For cosexual plants, the pattern is considered to vary with environmental conditions and resources status (commonly associated with plant size), hence, induce to changed fitness contributions through these functions (Freeman et al 1981;Lloyd and Bawa 1984;Brunet 1992;Sakai 2000). Evidence of size or environment mediated sexual investment has been documented in numerous studies (de Jong and Klinkhamer1989; Klinkhamer et al 1997;Wright and Barrett 1999;Ashman et al 2001;Guitián et al 2003;Méndez and Traveset 2003;Guitián et al 2004;Zhao et al 2008). In addition, over evolutionary time, primary sex allocation (e.g.…”

Geographic variation in primary sex allocation per flower within and among 12 species of Pedicularis (Orobanchaceae): Proportional male investment increases with elevation

“…For example, Klinkhamer et al (1997 ) and Zhang and Jiang (2002) predict that larger plants should allocate proportionally more resources to female function than smaller ones (given the male and female fi tness functions that we described). In support of these predictions and the assumptions underlying them, increasing female function with plant size has been observed within populations of numerous species ( Klinkhamer et al, 1997 ;Wright and Barrett, 1999 ;M é ndez and Traveset, 2003 ;Tomimatsu and Ohara, 2006 ;Hiraga and Sakai, 2007 ;Zhao et al, 2008 ; for contrasting results, see Ackerly and Jasienski, 1990 ;Bickel and Freeman, 1993 ;Ashman et al, 2001 ;Ishii, 2004 ;Cao et al, 2007 ), including 10 of the 16 wellsampled populations examined here ( Table 2 ). The factors infl uencing size-dependent sex allocation among population means, however, may differ from those operating within populations, especially where populations occupy distinct habitats or microclimates.…”

“…In particular, sex allocation per fl owerthe relative investment in fl oral and/or fruit traits related to male vs. female function -should evolve with plant resource status if female and male components of fi tness are differentially affected by changes in size or condition ( Charnov, 1982 ;Lloyd and Bawa, 1984 ;Iwasa, 1991 ;Klinkhamer et al, 1997 ). Evidence of size-dependent sexual investment has been documented in numerous studies, generally confi rming the prediction that larger plants invest proportionally more in female function ( de Jong and Klinkhamer, 1989 ;Kudo, 1993 ;Klinkhamer et al, 1997 ;Wright and Barrett, 1999 ;Ashman et al, 2001 ;M é ndez and Traveset, 2003 ;Tomimatsu and Ohara, 2006 ;Hiraga and Sakai, 2007 ;Zhao et al, 2008 ; but see Andersson, 1988 ;Mazer and Dawson, 2001 ;and Ishii, 2004 for contrasting results).…”

“…In previous studies, environmental effects on sex allocation within species ( Dawson and Bliss, 1989 ;Galen, 2000 ;Paquin and Aarssen, 2004 ;Zhao et al, 2008 ) and effects of elevation on female reproduction ( Cruden, 1972 ;Hilligardt, 1993 ;Gugerli, 1998 ) have been detected, but none focused on the sex allocation independently of the effects of such factors on plant size.…”