Seed size variation impacts local adaptation and life-history strategies in a perennial grass - PubMed Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 May 10;290(1998):20222460.
doi: 10.1098/rspb.2022.2460. Epub 2023 May 3.

Seed size variation impacts local adaptation and life-history strategies in a perennial grass

Samsad Razzaque  1 , Robert W Heckman  1 , Thomas E Juenger  1
Affiliations

Seed size variation impacts local adaptation and life-history strategies in a perennial grass

Samsad Razzaque et al. Proc Biol Sci. .

Abstract

Seed mass is an ecologically important trait that often differs considerably among ecotypes. Yet, because few studies examine the impacts of seed mass on adult life-history traits, its role in local adaptation is unclear. In this study, using accessions of Panicum hallii that spanned the two major ecotypes, we examined whether covariation between seed mass, seedling and reproductive traits impacts ecotypic divergence and local adaptation. The perennial grass P. hallii has two distinct ecotypes-a large-seeded upland ecotype adapted to xeric environments and a small-seeded lowland ecotype adapted to mesic environments. In the greenhouse, seed mass varied greatly across P. hallii genotypes in a manner consistent with ecotypic divergence. Seed mass covaried significantly with several seedling and reproductive traits. At field sites representing the habitats of the two ecotypes, seed mass had different impacts on seedling and adult recruitment: selection favoured large seeds in upland habitat and small seeds in lowland habitat, which was consistent with local adaptation. By demonstrating the central role of seed mass in ecotypic differences in P. hallii and its importance to seedling and adult recruitment under field conditions, these studies show that early life-history traits can promote local adaptation and potentially explain ecotype formation.

Keywords: ecotypic differentiation; life-history evolution; local adaptation; trade-off.

PubMed Disclaimer

Conflict of interest statement

We declare we have no competing interests.

Figures

Figure 1.
Figure 1.
Linear discriminant analysis of seed, seedling and reproductive traits in Panicum hallii. Points represents the means of individual genotypes. The lowland ecotype is blue, the sympatric ecotype is black, and the upland ecotype is red. Each ecotype's multivariate mean is denoted by a ‘+’ marker. 95% confidence level ellipses are plotted for each ecotype mean. The genome reference lines of the upland genotype (HAL2) and lowland genotype (FIL2) are marked as ‘♦’ in the plot. Traits: SM, seed mass; SL, shoot length; RL, root length; GT, germination time; GP, germination percentage; FT, flowering time; ABM, aboveground biomass; SN, seed number.
Figure 2.
Figure 2.
Proportion of variance in seed, seedling, and reproductive traits explained by ecotype, population group, and genotype. Values were calculated from a random effects model parameterized with a nested effect of genotype within population group within ecotype.
Figure 3.
Figure 3.
Effect of climate-of-origin variables on seed mass in P. hallii. Points are the model-averaged mean effects and error bars represent 95% confidence intervals.
Figure 4.
Figure 4.
Relationship between seed mass (mg) and (a) germination time (hours), (b) percentage of seeds germinating, (c) shoot length at 18 days after germinating (mm), (d) root length at 18 days after germinating (mm), (e) flowering time (days), (f) the number of seeds produced by each plant, (g) aboveground biomass at harvest (mg). All models were performed using standardized major axis regression, including an interaction between traits and ecotypes. Here, points represent genotype-level means.
Figure 5.
Figure 5.
(a) Seedling and (b) adult recruitment at two sites that represent typical mesic and xeric P. hallii habitats. For each panel, lowland is coloured blue, sympatric group is coloured black, and upland is coloured red. Means and confidence intervals were calculated from a Poisson GLM. Error bars represent 1 standard error.
Figure 6.
Figure 6.
The influence of seed mass on (a) seedling and (b) adult recruitment at two sites that represent typical mesic and xeric P. hallii habitat. For each panel, xeric and mesic sites are coloured red and blue, respectively. Shaded area corresponds to the 80% credible intervals.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Grime JP, Hodgson JG, Hunt R. 2014. Comparative plant ecology: a functional approach to common British species. Berlin, Germany: Springer.
    1. Leishman MR, Westoby M. 1992. Classifying plants into groups on the basis of associations of individual traits: evidence from Australian semi-arid woodlands. J. Ecol. 80, 417-424. (10.2307/2260687) - DOI
    1. Westoby M, Rice B. 1982. Evolution of the seed plants and inclusive fitness of plant tissues. Evolution 36, 713-724. (10.2307/2407884) - DOI - PubMed
    1. Venable DL. 1992. Size-number trade-offs and the variation of seed size with plant resource status. Am. Nat. 140, 287-304. (10.1086/285413) - DOI
    1. Moles AT, Westoby M. 2006. Seed size and plant strategy across the whole life cycle. Oikos 113, 91-105. (10.1111/j.0030-1299.2006.14194.x) - DOI

Publication types

LinkOut - more resources