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The effect of growth conditions on the seed size/number trade-off.

Paul-Victor C, Turnbull LA - PLoS ONE (2009)

Bottom Line: However, in comparative studies, empirical support for a slope of -1 is limited and contentious, leading some to question the utility of this concept.Second, we present experimental results using a population of recombinant inbred lines (RILs) of Arabidopsis thaliana.We re-grew lines in small pots (10 and 40 mm diameter) in a nutrient-poor substrate so that final adult size was heavily restricted by pot size.

View Article: PubMed Central - PubMed

Affiliation: Institute of Environmental Sciences, University of Zurich, Zurich, Switzerland.

ABSTRACT

Background: If the amount of resources allocated to reproduction (K) is fixed, then an increase in seed mass (S) can only be achieved by a decrease in seed number (n = K/S). Thus, log(n) = log(K)-log(S) producing a slope of -1 when seed mass and number are plotted on log-log axes. However, in comparative studies, empirical support for a slope of -1 is limited and contentious, leading some to question the utility of this concept.

Methodology/principal findings: First, we show that the expected slope depends on whether genotypes and species producing seeds of different mass are expected to reach the same adult size and that this in turn depends partly on the nature of growth. Second, we present experimental results using a population of recombinant inbred lines (RILs) of Arabidopsis thaliana. When these RILs are grown in large pots with plentiful nutrients, they exhibit a trade-off between seed size and number with a slope of -1.68 (+/-0.18) on log-log axes. This occurs because of genetic correlations between seed mass and adult size so that, under the right growth conditions, lines producing lighter seeds have the genetic potential to produce larger rosettes and hence a greater total mass of seeds. We re-grew lines in small pots (10 and 40 mm diameter) in a nutrient-poor substrate so that final adult size was heavily restricted by pot size.

Conclusions/significance: Under our growth conditions, small-seeded lines were unable to produce a greater total mass of seeds. Hence a trade-off emerged between seed mass and seed number with a slope of -1.166+/-0.319 on log-log axes in 40-mm diameter pots (close to the expected value of -1), although the slope was 0.132+/-0.263 in 10-mm diameter pots, demonstrating that the nature of the trade-off is sensitive to the growth conditions.

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Results of a variance components analysis of harvested seed mass (A) and seed number (B).Variance components are expressed as percentages of the total in each case. Note that seed mass shows a large genetic component (variation among lines) whereas seed number shows a large environmental component (variation among pot sizes).
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pone-0006917-g002: Results of a variance components analysis of harvested seed mass (A) and seed number (B).Variance components are expressed as percentages of the total in each case. Note that seed mass shows a large genetic component (variation among lines) whereas seed number shows a large environmental component (variation among pot sizes).

Mentions: We begin by fitting a model for both harvested seed size and harvested seed number with all terms fitted as random effects, as recommended by Gelman and Hill [34]. This provides a general overview of how the variance is partitioned between the various possible terms and their interactions. As expected, most of the variance (67%) in harvested seed mass exhibited by individual plants is due to lines: i.e. seed mass is under strong genetic control (Figure 2A) which explains the highly significant correlations obtained between our data and previous datasets (Table 1). In contrast, most of the variance in harvested seed number (85%) is due to pot diameter, i.e. to the environment (Figure 2B). Interestingly, the correlation between seed number in our experiment and a previous dataset are weaker (Table 2), indicating that lines that performed well in our experiment did not necessarily perform well in a previous experiment. The interaction between the genetic and environmental component appears to be very small in both cases (<1%, Figure 2).


The effect of growth conditions on the seed size/number trade-off.

Paul-Victor C, Turnbull LA - PLoS ONE (2009)

Results of a variance components analysis of harvested seed mass (A) and seed number (B).Variance components are expressed as percentages of the total in each case. Note that seed mass shows a large genetic component (variation among lines) whereas seed number shows a large environmental component (variation among pot sizes).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2735032&req=5

pone-0006917-g002: Results of a variance components analysis of harvested seed mass (A) and seed number (B).Variance components are expressed as percentages of the total in each case. Note that seed mass shows a large genetic component (variation among lines) whereas seed number shows a large environmental component (variation among pot sizes).
Mentions: We begin by fitting a model for both harvested seed size and harvested seed number with all terms fitted as random effects, as recommended by Gelman and Hill [34]. This provides a general overview of how the variance is partitioned between the various possible terms and their interactions. As expected, most of the variance (67%) in harvested seed mass exhibited by individual plants is due to lines: i.e. seed mass is under strong genetic control (Figure 2A) which explains the highly significant correlations obtained between our data and previous datasets (Table 1). In contrast, most of the variance in harvested seed number (85%) is due to pot diameter, i.e. to the environment (Figure 2B). Interestingly, the correlation between seed number in our experiment and a previous dataset are weaker (Table 2), indicating that lines that performed well in our experiment did not necessarily perform well in a previous experiment. The interaction between the genetic and environmental component appears to be very small in both cases (<1%, Figure 2).

Bottom Line: However, in comparative studies, empirical support for a slope of -1 is limited and contentious, leading some to question the utility of this concept.Second, we present experimental results using a population of recombinant inbred lines (RILs) of Arabidopsis thaliana.We re-grew lines in small pots (10 and 40 mm diameter) in a nutrient-poor substrate so that final adult size was heavily restricted by pot size.

View Article: PubMed Central - PubMed

Affiliation: Institute of Environmental Sciences, University of Zurich, Zurich, Switzerland.

ABSTRACT

Background: If the amount of resources allocated to reproduction (K) is fixed, then an increase in seed mass (S) can only be achieved by a decrease in seed number (n = K/S). Thus, log(n) = log(K)-log(S) producing a slope of -1 when seed mass and number are plotted on log-log axes. However, in comparative studies, empirical support for a slope of -1 is limited and contentious, leading some to question the utility of this concept.

Methodology/principal findings: First, we show that the expected slope depends on whether genotypes and species producing seeds of different mass are expected to reach the same adult size and that this in turn depends partly on the nature of growth. Second, we present experimental results using a population of recombinant inbred lines (RILs) of Arabidopsis thaliana. When these RILs are grown in large pots with plentiful nutrients, they exhibit a trade-off between seed size and number with a slope of -1.68 (+/-0.18) on log-log axes. This occurs because of genetic correlations between seed mass and adult size so that, under the right growth conditions, lines producing lighter seeds have the genetic potential to produce larger rosettes and hence a greater total mass of seeds. We re-grew lines in small pots (10 and 40 mm diameter) in a nutrient-poor substrate so that final adult size was heavily restricted by pot size.

Conclusions/significance: Under our growth conditions, small-seeded lines were unable to produce a greater total mass of seeds. Hence a trade-off emerged between seed mass and seed number with a slope of -1.166+/-0.319 on log-log axes in 40-mm diameter pots (close to the expected value of -1), although the slope was 0.132+/-0.263 in 10-mm diameter pots, demonstrating that the nature of the trade-off is sensitive to the growth conditions.

Show MeSH
Related in: MedlinePlus