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Herbaceous Perennials (herbaceous + perennial)
Selected AbstractsEffects of population succession on demographic and genetic processes: predictions and tests in the daylily Hemerocallis thunbergii (Liliaceae)MOLECULAR ECOLOGY, Issue 13 2007MI YOON CHUNG Abstract Spatial genetic structure within plant populations is influenced by variation in demographic processes through space and time, including a population's successional status. To determine how demographic structure and fine-scale genetic structure (FSGS) change with stages in a population's successional history, we studied Hemerocallis thunbergii (Liliaceae), a nocturnal flowering and hawkmoth-pollinated herbaceous perennial with rapid population turnover dynamics. We examined nine populations assigned to three successive stages of population succession: expansion, maturation, and senescence. We developed stage-specific expectations for within-population demographic and genetic structure, and then for each population quantified the spatial aggregation of individuals and genotypes using spatial autocorrelation methods (nonaccumulative O-ring and kinship statistics, respectively), and at the landscape level measured inbreeding and genetic structure using Wright's F -statistics. Analyses using the O-ring statistic revealed significant aggregation of individuals at short spatial scales in expanding and senescing populations, in particular, which may reflect restricted seed dispersal around maternal individuals combined with relatively low local population densities at these stages. Significant FSGS was found for three of four expanding, no mature, and only one senescing population, a pattern generally consistent with expectations of successional processes. Although allozyme genetic diversity was high within populations (mean %P = 78.9 and HE = 0.281), landscape-level differentiation among sites was also high (FST = 0.166) and all populations exhibited a significant deficit of heterozygotes relative to Hardy,Weinberg expectations (range F = 0.201,0.424, mean FIS = 0.321). Within populations, F was not correlated with the degree of FSGS, thus suggesting inbreeding due primarily to selfing as opposed to mating among close relatives in spatially structured populations. Our results demonstrate considerable variation in the spatial distribution of individuals and patterns and magnitude of FSGS in H. thunbergii populations across the landscape. This variation is generally consistent with succession-stage-specific differences in ecological processes operating within these populations. [source] Characterization of microsatellite loci in Kearney's bluestar (Amsonia kearneyana) and cross-amplification in other Amsonia speciesMOLECULAR ECOLOGY RESOURCES, Issue 4 2004J. RICK TOPINKA Abstract Kearney's bluestar (Amsonia kearneyana) is a highly endangered herbaceous perennial in the family Apocynaceae. The species is found only in the Baboquivari Mountains of southern Arizona. We report the isolation and development of 12 microsatellite loci for Kearney's bluestar. Numbers of alleles ranged from two to four and observed heterozygosities ranged from 0.20 to 0.80 in the nine loci found to be polymorphic in the test population. All loci were also tested for cross-amplification in five other Amsonia species representing two subgenera from the southwestern United States. Some loci that were not polymorphic in the Kearney's bluestar were polymorphic in other species. [source] The evolutionary ecology of vegetative dormancy in mature herbaceous perennial plantsJOURNAL OF ECOLOGY, Issue 5 2009Richard P. Shefferson Summary 1.,I present an evolutionary ecology interpretation of vegetative dormancy in mature herbaceous perennials. This kind of vegetative dormancy has been noted for at least 40 years, but has only recently become a topic of study. 2.,Vegetative dormancy may be considered in a life-history context. Both vegetative dormancy and mortality typically decrease with increasing size. Vegetative dormancy's relationship to reproduction is more complex, because some species increase flowering and fruiting after dormancy while others do the opposite. 3.,If vegetative dormancy is adaptive, then it is most likely a bet-hedging trait. Dormancy-prone plants are often long-lived, and in such organisms, bet-hedging traits should counter the effects of environmental stochasticity on adult survival. This adaptive context may vary by life span, because in shorter-lived plants, fitness is most sensitive to changes in reproduction rather than survival. 4.,Vegetative dormancy could evolve if the costs of sprouting ever outweigh the benefits. The benefits of sprouting include: (i) photosynthesis and (ii) the opportunity to flower and reproduce. The costs include: (i) greater chance of herbivory, (ii) greater need for limiting nutrients, and (iii) greater maintenance costs. The many losses of photosynthesis among plants suggest that these benefits may not always outweigh the costs. 5.,Vegetative dormancy may be an evolutionary step towards the loss of photosynthesis. Many non-photosynthetic plants acquire carbon from their mycorrhizal fungi. Many autotrophic, dormancy-prone plants also acquire some carbon from their mycorrhizal fungi. Further, non-photosynthetic plants often become dormant to an even greater extent than autotrophic, dormancy-prone plants. 6.Synthesis,Vegetative dormancy often occurs in clades with non-photosynthetic, myco-heterotrophic plants, with implications for the evolution of traits involved in carbon nutrition. The links between vegetative dormancy, other life-history traits, mycorrhizas and the loss of photosynthesis should provide exciting directions for further research in plant evolutionary ecology. Particularly needed is an assessment of the physiology of vegetative dormancy, including whether the mycorrhiza is a carbon source in all dormancy-prone plant species. Equally important is a better understanding of the genetic relationships among photosynthesis, myco-heterotrophy and dormancy. [source] The relationship of total and per-gram rankings in competitive effect to the natural abundance of herbaceous perennialsJOURNAL OF ECOLOGY, Issue 1 2001Timothy G. Howard Summary 1,Using a field experiment and a garden experiment, I estimated the rankings in total and per-gram competitive effect of non-woody perennial old-field species. 2,Total competitive effects were defined as the relative reduction in growth of a target from no-neighbour to with-neighbour conditions. Per-gram competitive effects were defined as the per-unit relative reduction in target growth among increasing neighbour densities, and were determined from the shape of a nonlinear curve fit through a distribution of normalized target performance against neighbour mass. 3,In both experiments, mean total competitive effect differed significantly among species, indicating a strong competitive hierarchy. In the garden experiment only species at opposite ends of the ranking differed significantly in per-gram competitive effect, resulting in a weaker competitive hierarchy based on this measure. 4,Nonetheless, rankings of per-gram competitive effect were more strongly correlated with rank in abundance than were rankings of total competitive effect. 5,Per-gram competitive effect may be more predictive of natural abundance than total competitive effect for at least two reasons. The effects of neighbour abundance on targets are nonlinear, and unlike total effects, per-gram estimates of competitive effect may therefore indicate how competition changes over time with changing neighbour densities. Also, if higher per-gram competitive effect reflects higher per-unit nutrient uptake rates, it would probably be advantageous to a species throughout the individual's life span, rather than only when the individual is larger than its surrounding neighbours. [source] Water Sources and Water-Use Efficiency in Mediterranean Coastal Dune VegetationPLANT BIOLOGY, Issue 3 2004G. A. Alessio Abstract: In coastal environments plants have to cope with various water sources: rainwater, water table, seawater, and mixtures. These are usually characterized by different isotopic signatures (18O/16O and D/H ratios). Xylem water reflects the isotopic compositions of the water sources. Additionally, water-use efficiency (WUE) can be assessed with carbon isotope discrimination (,) analyses. Gas exchange, , of leaf dry matter, and isotopic composition (,18O) of xylem water were measured from June to August 2001 in herbaceous perennials of mobile dunes (Ammophila littoralis, Elymus farctus) and sclerophyllous shrubs and climbers (Arbutus unedo, Pistacia lentiscus, Phillyrea angustifolia, Qercus ilex, Juniperus oxycedrus, Smilax aspera) of consolidated dunes. Assimilation rates were rather low and did not show clear seasonal patterns, possibly due to limited precipitation and generally low values of stomatal conductance. The lowest values were shown in S. aspera. Different physiological patterns were found, on the basis of ,18O and , analyses. Values of ,18O of xylem water of phanerophytes were remarkably constant and matched those of the water table, indicating dependence on a reliable water source; values of , were relatively high, indicating low intrinsic WUE, with the exception of J. oxycedrus. Surprisingly, very high ,18O values were found for the xylem water from S. aspera in August. This suggests retrodiffusion of leaf water to xylem sap in the stem or direct uptake of water by leaves or stems, owing to dew or fog occurrence. Low , values indicated high WUE in S. aspera. Contrasting strategies were shown by the species of mobile dunes: E. farctus relied on superficial water and exhibited low WUE, accordingly to its therophyte-like vegetative cycle; on the contrary, A. littoralis used deeper water sources, showing higher WUE in relation to its long-lasting vegetative habit. [source] | ||||||||||