Seedling Relative Growth Rate and its Components in Relation to Seed Size: Phylogenetically Independent Contrasts

Swanborough, Perry W.; Westoby, Mark

doi:10.2307/2389841

Cited by 113 publications

(83 citation statements)

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“…We found that the RGRs of PC and HS seedlings from larger seeds were lower than GS from smaller seeds and the correlation between RGR and habitats contrasted to that of seed weight. Seed size is also related to resource allocation and larger-seeded species might be able to allocate a larger proportion of mass to roots rather than shoots during early growth (Jurado and Westoby, 1992;Swanborough and Westoby, 1996). In our result, PC and HS seedling root was significantly longer and heavier than GS seedling root.…”

Section: Variation In Seed Size and Growth Processsupporting

confidence: 43%

Ecotypic differentiation in seed and seedling morphology and physiology among Cicuta virosa populations

Shin

Kim

2013

Aquatic Botany

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a b s t r a c tThere are three different Cicuta virosa habitats in Korea: Pyeongchang (PC), a fenced wet meadow with a water shortage in spring; Hoengseng (HS), a 12 year old abandoned paddy field and narrow streamlet holding shallow water throughout the year; Gunsan (GS), a 1 m deep reservoir with a floating mat composed of organic matter located 2 • south of HS and PC and at very low altitude. These three populations with different altitudes, climates, water regimes and nutrient availability showed differences in leaf morphology and flowering time. We compared seed and seedling morphology and tested the sensitivity of seedlings to dryness and shade and the germination responses to light and temperature to identify intraspecific variation as ecotypic differences in C. virosa populations (p ≤ 0.05). The seed length of GS (2.04 ± 0.03 mm) was significantly shorter than that of PC (2.44 ± 0.05 mm) and HS (2.60 ± 0.03 mm). Seed weight of GS (0.83 ± 0.01 mg) was significantly lighter than that of the others (PC: 1.47 ± 0.02 mg, HS: 1.33 ± 0.02 mg). PC and HS seedlings had larger root: shoot ratio values and GS had significantly higher relative growth rate (RGR) through 8 weeks of growth. GS seedlings were more sensitive to dryness than PC and HS in leaf chlorophyll contents, specific leaf area (SLA) and RGR. The pattern of germination responses was similar among the three populations but germination rate (%) was very different. Maximum germination percentages were 63.0%, 23.9% and 96.9% in PC, HS, and GS, respectively, under 28/18 • C/14 h photoperiod. The nonviable seed (%) of GS (18.1 ± 0.7%) was significantly higher than that of the others (PC: 3.1 ± 1.6%, HS: 3.4 ± 0.6%) in the tetrazolium tests result. Seed mass which was correlated to other plant traits (i.e., root:shoot ratio, RGR) and germination rate were the most discriminating variables in the discriminant analysis. Seed weight was negatively correlated with temperature in January and water level and germination rate was significantly related with water level and water temperature in August. Based on these results under uniform conditions, we suggest that these three C. virosa populations from different habitats are ecotypes.

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Section: Variation In Seed Size and Growth Processsupporting

confidence: 43%

Ecotypic differentiation in seed and seedling morphology and physiology among Cicuta virosa populations

Shin

Kim

2013

Aquatic Botany

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“…A larger seed and seedling may confer advantages during establishment as stress tolerance increases with size (Saverimuttu and Westoby 1996;Swanborough and Westoby 1996). Species from SFF tend to have large seeds.…”

Section: Drought Severity Differential Mortality and Changes In Forementioning

confidence: 99%

Interannual variation in rainfall, drought stress and seedling mortality may mediate monodominance in tropical flooded forests

López

Kursar

2007

Oecologia

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Flood tolerance is commonly regarded as the main factor explaining low diversity and monodominance in tropical swamps. In this study we examined seedling mortality in relation to seasonally, i.e., flooding versus drought, of the dominant tree species (Prioria copaifera), and three associated species (Pterocarpus ojficinalis, Carapa guianensis and Pentaclethra macroloba), in seasonally flooded forests (SFF) in Darien, Panama. Seedling mortality differed among species, years and seasons. Prioria seedlings experienced the lowest overall mortality, and after 3 years many more Prioria seedlings remained alive than those of any of the associated species. In general, within species, larger seedlings had greater survival. Seed size, which can vary by close to 2 orders of magnitude in Prioria, had a confounding effect with that of topography. Large-seeded Prioria seedlings experienced 1.5 times greater mortality than small-seeded seedlings, as large-seeded Prioria seedlings were more likely to be located in depressions. This finding suggests that seed size, plant size and topography are important in understanding SFF regeneration. For all species, seedling mortality was consistently greater during the dry season than during flooding. For Prioria, dry season seedling mortality was correlated with drought stress, that is, high mortality during the long El Nino dry season of 1998 and the normal dry season of 2000, but very low dry season mortality during the mild dry season of 1999. Prioria's ability to dominate in seasonally flooded forest of Central America is partly explained by its low drought-related mortality in comparison to associated species.

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“…1). Westoby 1993;Saverimuttu and Westoby 1996;Swanborough and Westoby 1996). Comparisons of species pairs, which invoke only a minimal level of phylogenetic information, have been widely used in plant ecology dating back to Salisbury (1942).…”

Section: Fig 1 (A)mentioning

confidence: 99%

Taxon Sampling, Correlated Evolution, and Independent Contrasts

2000

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Abstract. Independent contrasts are widely used to incorporate phylogenetic information into studies of continuous traits, particularly analyses of evolutionary trait correlations, but the effects of taxon sampling on these analyses have received little attention. In this paper, simulations were used to investigate the effects of taxon sampling patterns and alternative branch length assignments on the statistical performance of correlation coefficients and sign tests; ''fulltree'' analyses based on contrasts at all nodes and ''paired-comparisons'' based only on contrasts of terminal taxon pairs were also compared. The simulations showed that random samples, with respect to the traits under consideration, provide statistically robust estimates of trait correlations. However, exact significance tests are highly dependent on appropriate branch length information; equal branch lengths maintain lower Type I error than alternative topological approaches, and adjusted critical values of the independent contrast correlation coefficient are provided for use with equal branch lengths. Nonrandom samples, with respect to univariate or bivariate trait distributions, introduce discrepancies between interspecific and phylogenetically structured analyses and bias estimates of underlying evolutionary correlations. Examples of nonrandom sampling processes may include community assembly processes, convergent evolution under local adaptive pressures, selection of a nonrandom sample of species from a habitat or life-history group, or investigator bias. Correlation analyses based on species pairs comparisons, while ignoring deeper relationships, entail significant loss of statistical power and as a result provide a conservative test of trait associations. Paired comparisons in which species differ by a large amount in one trait, a method introduced in comparative plant ecology, have appropriate Type I error rates and high statistical power, but do not correctly estimate the magnitude of trait correlations. Sign tests, based on full-tree or paired-comparison approaches, are highly reliable across a wide range of sampling scenarios, in terms of Type I error rates, but have very low power. These results provide guidance for selecting species and applying comparative methods to optimize the performance of statistical tests of trait associations.

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Seedling Relative Growth Rate and its Components in Relation to Seed Size: Phylogenetically Independent Contrasts

Cited by 113 publications

References 0 publications

Ecotypic differentiation in seed and seedling morphology and physiology among Cicuta virosa populations

Ecotypic differentiation in seed and seedling morphology and physiology among Cicuta virosa populations

Interannual variation in rainfall, drought stress and seedling mortality may mediate monodominance in tropical flooded forests

Taxon Sampling, Correlated Evolution, and Independent Contrasts

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