Linking vegetative dormancy to fitness in two long‐lived herbaceous perennials

Abstract

Abstract. Vegetative dormancy occurs in many plant families, but its evolutionary context remains a mystery. We asked whether vegetative dormancy is an adaptive response to environmental stress and environmental stochasticity in certain long-lived plant species. We conducted an in situ experimental study in two and three populations of Cypripedium calceolus and Cephalanthera longifolia, respectively, in Estonia. Plants were defoliated, shaded, or simply observed at the beginning of the growing season in 2002 and 2003, and monitored demographically through 2008. We assessed links between fitness and vegetative dormancy using stochastic life table response experiments (SLTREs), in which the impact of treatment on the log stochastic population growth rate (a ¼ log k S ) via shifts in projection matrix transitions in treated plants relative to controls was used to assess the fitness impacts of treatment-induced life history responses. In Cypripedium, the observed lifespans of individuals that became vegetatively dormant in 2003/04 was significantly higher than plants that had not done so (P ¼ 0.050). Defoliation and shading resulted in lower levels of flowering in both species. Both defoliation and shading decreased a relative to controls in Cypripedium and Cephalanthera. Defoliation-and shading-induced shifts in transitions involving vegetative dormancy were generally associated with significantly positive SLTRE contributions to Da, and shifts in the standard deviations of demographic rates generally contributed little to Da. Thus, vegetative dormancy is likely to be an adaptive response to environmental stress and stochasticity. Further work on the genetic basis to vegetative dormancy will clarify whether enough heritability may have existed in the past, or exists now, to support vegetative dormancy as an adaptation.

Demographic shifts related to mycoheterotrophy and their fitness impacts in two Cephalanthera species

“…), and protocorms are thought to be capable of existing for multiple years without becoming photosynthetic seedlings, but little data exist on the actual transition probabilities (Shefferson et al. , Roy et al. ).…”

“…In addition, we assumed that seed dormancy probability was 0.25, probability of stasis as a protocorm was 0.20, and the probability of transitioning to seedling from protocorm was 0.25, regardless of phenotype and population, per a previously published study on a different Estonian population of C. longifolia (Shefferson et al. ). We tested the impacts of these assumptions by redoing the sensitivity, elasticity, and LTRE analyses (all described below) using altered but realistic versions of fruit production rate, seed germination, and seed dormancy (±1000 seeds/fruit, ±10% seed germination, ±10% seed dormancy), but found no qualitative difference with the results presented here.…”

“…We further assumed that seedlings could develop into adults with the same probabilities of survival and transition as vegetatively dormant adults (Shefferson et al. ). Adult size classes were based on the number of sprouts per plant in C. damasonium , and the total number of leaves per plant in C. longifolia .…”

“…In both species, seeds are likely capable of long-term dormancy (see Tešitelová et al 2012, for related Epipactis spp. ), and protocorms are thought to be capable of existing for multiple years without becoming photosynthetic seedlings, but little data exist on the actual transition probabilities (Shefferson et al 2012, Roy et al 2013. Per previously published field germination studies on these populations, we assumed that green and albino individuals produced 7339 ± 2371 and 2554 ± 1557 seeds per fruit (mean ± 1 SE), respectively (Roy et al 2013), and that green and albino seed germinated to the protocorm stage at probabilities of 0.79 ± 0.02% and 0.55 ± 0.01%, respectively (Roy et al 2013).…”

Cypripedium calceolus (Orchidaceae) in Central Russia: a case study for its populations in two protected areas in the Republic of Mordovia (Russia)

“…In different regions of Eurasia, C. calceolus has been estimated as Near Threatened (Bilz 2011, Turis et al 2014, Vulnerable (Rassi et al 2001), Endangered (Witkowski et al 2003), and Critically Endangered (Blinova & Uotila 2011, Khapugin et al 2017a, Khapugin et al 2017c. International studies on C. calceolus related to its genetic diversity (Brzosko et al 2009, Brzosko et al 2011, Fay et al 2009, Kļaviņa et al 2014, Minasiewicz & Znaniecka 2014, population ecology and biology (Blinova 2002, Brzosko 2002, Davison et al 2013, Fardeeva et al 2010, Gajewski & Marcisz 2014, Khapugin et al 2014, Korczyński & Krasicka-Korczyńska 2014, García et al 2002, García et al 2010, Gorchakovskii & Igosheva 2003, Kirillova 2015, Kull 1998, Nicolè et al 2005, Puchnina 2017, Stetsuk 2013, Zheleznaya 2015, impacts of environment conditions and stress-factors on the species (Blinova 2002, Czerepko et al 2014, Kirillova 2016, Kirillova et al 2012, Puchnina 2017, Shefferson et al 2012, pollination (Antonelli et al 2009, Tremblay 1994, as well as the list of publications with new records of this threatened species is continuously enlarging ...…”