ENVIRONMENTAL AND GENETIC SOURCES OF DIVERSIFICATION IN THE TIMING OF SEED GERMINATION: IMPLICATIONS FOR THE EVOLUTION OF BET HEDGING

Andrew M. Simons; Mark O. Johnston

doi:10.1554/05-396.1

Ecological niche and bet-hedging strategies for Triodia (R.Br.) seed germination

Annals of Botany ◽

10.1093/aob/mcx158 ◽

2017 ◽

Vol 121 (2) ◽

pp. 367-375 ◽

Cited By ~ 14

Author(s):

Wolfgang Lewandrowski ◽

Todd E Erickson ◽

Emma L Dalziell ◽

Jason C Stevens

Keyword(s):

Seed Germination ◽

Ecological Niche ◽

Bet Hedging ◽

Hedging Strategies

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Seed Germination in Desert Annuals: An Empirical Test of Adaptive Bet Hedging

The American Naturalist ◽

10.2307/3078941 ◽

2000 ◽

Vol 155 (2) ◽

pp. 168

Author(s):

Clauss ◽

Venable

Keyword(s):

Seed Germination ◽

Empirical Test ◽

Bet Hedging ◽

Desert Annuals

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Seed heteromorphy influences seed longevity in Aegilops

Seed Science Research ◽

10.1017/s096025851800034x ◽

2018 ◽

Vol 28 (4) ◽

pp. 277-285 ◽

Cited By ~ 6

Author(s):

Filippo Guzzon ◽

Simone Orsenigo ◽

Maraeva Gianella ◽

Jonas V. Müller ◽

Ilda Vagge ◽

...

Keyword(s):

Seed Germination ◽

Field Experiments ◽

Soil Seed Bank ◽

Seedling Emergence ◽

Seed Longevity ◽

Ex Situ ◽

Bet Hedging ◽

Hedging Strategy ◽

Seed Conservation ◽

Germination Phenology

AbstractThe genus Aegilops belongs to the secondary gene pool of wheat and has great importance for wheat cultivar improvement. As a genus with only annual species, regeneration from seeds in Aegilops is crucial. In several species in Aegilops, spikes produce different seed morphs, both in size and germination patterns. However, little is known about the ecology of seed germination, nor about the seed longevity in this genus. Here we investigated the germination phenology of Ae. neglecta under laboratory and field conditions and assessed longevity of different seed morphs of five additional Aegilops species using controlled ageing tests. Large seeds were short-lived and germinated faster than small seeds in most of the species. Field experiments with Ae. neglecta showed that large seeds of the dimorphic pair germinated 3 months after dispersal in contrast to 14 months for smaller seeds. Differences in longevity were detected not only in dimorphic seed pairs, but also among seeds from different positions on the spike. Our results indicate that different longevities in seed morphs of Aegilops may reflect a different soil seed bank persistence, with smaller seeds able to maintain a higher viability after dispersal than larger ones, thereby spreading seedling emergence over two years. Differences of seed germination and longevities between seed morphs in Aegilops may have important implications for ex situ seed conservation and reinforce the hypothesis of a bet-hedging strategy in the germination ecology of this genus.

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An ABA-GA bistable switch can account for natural variation in the variability of Arabidopsis seed germination time

10.1101/2020.06.05.135681 ◽

2020 ◽

Author(s):

Katie Abley ◽

Pau Formosa-Jordan ◽

Hugo Tavares ◽

Emily Chan ◽

Ottoline Leyser ◽

...

Keyword(s):

Seed Germination ◽

Phenotypic Variability ◽

Time Variability ◽

Bet Hedging ◽

Hedging Strategy ◽

Bistable Switch ◽

Germination Time ◽

Arabidopsis Seed ◽

Recombinant Inbred Population ◽

Exogenous Addition

AbstractGenetically identical plants growing in the same conditions can display heterogeneous phenotypes. Whether this phenotypic variability is functional and the mechanisms behind it are unclear. Here we use Arabidopsis seed germination time as a model system to examine phenotypic variability. We show extensive variation in seed germination time variability between Arabidopsis accessions, and use a multi-parent recombinant inbred population to identify two loci involved in this trait. Both loci include genes implicated in ABA signalling that could contribute to seed germination variability. Modelling reveals that the GA/ABA bistable switch underlying germination can amplify variability and account for the effects of these two loci on germination distributions. The model predicts the effects of modulating ABA and GA levels, which we validate genetically and by exogenous addition of hormones. We confirm that germination variability could act as a bet hedging strategy, by allowing a fraction of seeds to survive lethal stress.

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Fluctuating natural selection accounts for the evolution of diversification bet hedging

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2008.1920 ◽

2009 ◽

Vol 276 (1664) ◽

pp. 1987-1992 ◽

Cited By ~ 95

Author(s):

Andrew M. Simons

Keyword(s):

Seed Germination ◽

Time Scales ◽

Geometric Mean ◽

Empirical Support ◽

Natural Environments ◽

Bet Hedging ◽

Fluctuating Selection ◽

Quantitative Test ◽

Geometric Mean Fitness ◽

Germination Timing

Natural environments are characterized by unpredictability over all time scales. This stochasticity is expected on theoretical grounds to result in the evolution of ‘bet-hedging’ traits that maximize the long term, or geometric mean fitness even though such traits do not maximize fitness over shorter time scales. The geometric mean principle is thus central to our interpretation of optimality and adaptation; however, quantitative empirical support for bet hedging is lacking. Here, I report a quantitative test using the timing of seed germination—a model diversification bet-hedging trait—in Lobelia inflata under field conditions. In a phenotypic manipulation study, I find the magnitude of fluctuating selection acting on seed germination timing—across 70 intervals throughout five seasons—to be extreme: fitness functions for survival are complex and multimodal within seasons and significantly dissimilar among seasons. I confirm that the observed magnitude of fluctuating selection is sufficient to account for the degree of diversification behaviour characteristic of individuals of this species. The geometric mean principle has been known to economic theory for over two centuries; this study now provides a quantitative test of optimality of a bet-hedging trait in nature.

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