scholarly journals OFFSPRING SIZE VARIATION WITHIN BROODS AS A BET-HEDGING STRATEGY IN UNPREDICTABLE ENVIRONMENTS

Ecology ◽  
2008 ◽  
Vol 89 (9) ◽  
pp. 2506-2517 ◽  
Author(s):  
Dustin J. Marshall ◽  
Russell Bonduriansky ◽  
Luc F. Bussière
Keyword(s):  
Size Variation ◽  
Offspring Size ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Unpredictable Environments

scholarly journals Coping with environmental uncertainty: dynamic bet hedging as a maternal effect

2009 ◽  
Vol 364 (1520) ◽  
pp. 1087-1096 ◽  
Author(s):  
Angela J Crean ◽  
Dustin J Marshall
Keyword(s):  
Size Variation ◽  
Offspring Size ◽  
Bet Hedging ◽  
Maternal Environment ◽  
Unpredictable Environments ◽  
Theoretical Predictions ◽  
Environmental Unpredictability ◽  
The Mean ◽  
Empirical Tests ◽  
Response To Environmental Change

Mothers in a range of taxa manipulate the phenotype of their offspring in response to environmental change in order to maximize their own fitness. Most studies have focused on changes in the mean phenotype of offspring. Focusing on mean offspring phenotypes is appropriate for species in which mothers are likely to successfully predict the environment their offspring will experience, but what happens when the offspring's environment is unpredictable? Theory suggests that when mothers face uncertainty regarding their offspring's environment, they should increase within-clutch variation in the offspring phenotype (i.e. they should bet hedge). While comparative analyses support the idea that mothers do bet hedge in response to environmental unpredictability, empirical tests are very rare and it remains unclear whether mothers adaptively adjust variance in offspring traits (a phenomenon we call dynamic bet hedging). As a first step towards examining dynamic bet hedging, we reanalysed data from five previously published studies. These studies were across a range of taxa, but all manipulated the maternal environment/phenotype and then examined changes in mean offspring size. We found some support for the theoretical predictions that mothers should increase within-clutch offspring size variation when faced with unpredictable environments. We predict that dynamic bet hedging is more common than previously anticipated and suggest that it has some interesting implications for the studies that focus on shifts in mean offspring traits alone. Hence, future studies should examine maternal effects on both the mean and the variance of offspring traits.

scholarly journals Mutation rates in seeds and seed-banking influence substitution rates across the angiosperm phylogeny

2017 ◽  
Author(s):  
Marcel Dann ◽  
Sidonie Bellot ◽  
Sylwia Schepella ◽  
Hanno Schaefer ◽  
Aurélien Tellier
Keyword(s):  
Seed Storage ◽  
Branch Length ◽  
Population Diversity ◽  
Bet Hedging ◽  
Novel Mutations ◽  
Hedging Strategy ◽  
Substitution Rates ◽  
Unpredictable Environments ◽  
Nuclear Its ◽  
Selection Generation

Summary1)BackgroundSeed-banking (the ability to persist in the soil over many generations) is usually considered as a dormant stage where genotypes are “stored” as a bet-hedging strategy in response to unpredictable environments. However, seed dormancy may instead have consequences for the integrity of the DNA and generate novel mutations.2)MethodsWe address this paradox by building phylogenies based on the plastomes and nuclear ITS of species belonging to ten angiosperm clades. In each clade, the substitution rate (branch-length) of a seed-banking species is compared with that of a closely-related non-seed-banking species.3)ResultsSeed-banking species show as high or higher substitution rates than non-seedbanking species, and therefore mutations occur in dormant seeds at a rate at least as high as in above-ground plants. Moreover, seed born mutations have the same probability to reach fixation as those from above ground. Our results are robust to differences in selection, generation time, and polymorphism.4)ConclusionsMutations occurring in seeds, and thus seed-banking, affect the population diversity of plant species, and are observable at the macro-evolutionary scale. Our study has consequences for seed storage projects, since the stored seeds are likely to accumulate mutations at a higher rate than previously thought.

scholarly journals Phenotypic heterogeneity implements a game theoretic mixed strategy in a clonal microbial population

2014 ◽  
Author(s):  
David Healey ◽  
Jeff Gore
Keyword(s):  
Experimental Evidence ◽  
Evolutionary Game ◽  
Phenotypic Heterogeneity ◽  
Microbial Populations ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Unpredictable Environments ◽  
Game Theoretic ◽  
Pure Strategies ◽  
Genetic Mutants

Genetically identical cells in microbial populations often exhibit a remarkable degree of phenotypic heterogeneity even in homogenous environments. While such heterogeneity is often thought to be a bet-hedging strategy against unpredictable environments, evolutionary game theory also predicts phenotypic heterogeneity as a stable response to evolutionary "hawk-dove" games, in which rare strategies are favored over common ones. Here we provide experimental evidence for this game theoretic explanation in the context of the well-studied yeast GAL network. In an environment containing the two sugars glucose and galactose, the yeast GAL network displays stochastic bimodal activation. We show that genetic mutants playing the "pure" strategies of GAL-ON or GAL-OFF can each invade the opposite strategy when rare, indicating a hawk-dove game between the two. Consistent with the Nash equilibrium of an evolutionary game, the stable mix of pure strategists does not necessarily maximize the growth of the overall population. We also find that the wild type GAL network can invade populations of both pure strategists while remaining uninvasible by either. Taken together, our results provide experimental evidence that evolutionary hawk-dove games between identical cells can explain the phenotypic heterogeneity found in clonal microbial populations.

Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser
Keyword(s):  
Predation Risk ◽  
Reproductive Cycle ◽  
Perceived Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Size Variation ◽  
Egg Laying ◽  
Offspring Size ◽  
Natural Predation ◽  
Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

scholarly journals Individual reversible plasticity as a genotype‐level bet‐hedging strategy

2021 ◽  
Author(s):  
Thomas R. Haaland ◽  
Jonathan Wright ◽  
Irja I. Ratikainen
Keyword(s):  
Bet Hedging ◽  
Hedging Strategy

scholarly journals Seasonality and competition select for variable germination behavior in perennials

2022 ◽  
Author(s):  
Hanna ten Brink ◽  
Thomas Ray Haaland ◽  
Oystein Hjorthol Opedal
Keyword(s):  
Simulation Models ◽  
Population Variation ◽  
Priority Effects ◽  
Bet Hedging ◽  
Environmental Predictability ◽  
Hedging Strategies ◽  
Unpredictable Environments ◽  
Evolutionary Simulation ◽  
Negative Frequency Dependent Selection ◽  
Germination Timing

The common occurrence of within-population variation in germination behavior and associated traits such as seed size has long fascinated evolutionary ecologists. In annuals, unpredictable environments are known to select for bet-hedging strategies causing variation in dormancy duration and germination strategies. Variation in germination timing and associated traits is also commonly observed in perennials, and often tracks gradients of environmental predictability. Although bet-hedging is thought to occur less frequently in long-lived organisms, these observations suggest a role of bet-hedging strategies in perennials occupying unpredictable environments. We use complementary numerical and evolutionary simulation models of within- and among-individual variation in germination behavior in seasonal environments to show how bet-hedging interacts with density dependence, life-history traits, and priority effects due to competitive differences among germination strategies. We reveal substantial scope for bet-hedging to produce variation in germination behavior in long-lived plants, when "false starts" to the growing season results in either competitive advantages or increased mortality risk for alternative germination strategies. Additionally, we find that two distinct germination strategies can evolve and coexist through negative frequency-dependent selection. These models extend insights from bet-hedging theory to perennials and explore how competitive communities may be affected by ongoing changes in climate and seasonality patterns.

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