Dealing with stochastic environmental variation in space and time: bet hedging by generalist, specialist, and diversified strategies

Crowley, Philip H.; Ehlman, Sean M.; Korn, Evelyn; Sih, Andrew

doi:10.1007/s12080-015-0272-x

Cited by 26 publications

(38 citation statements)

References 27 publications

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“…In the years of the high population, the densities increased everywhere. This interesting observation supports the bet‐hedging strategy in space and time (Crowley, Ehlman, Korn, & Sih, ), where high and low number of vendace off‐spring is allocated widely to the potential habitats around the lakes. In boreal oligotrophic large lakes with fragmented morphology and broken shoreline, weather and other environmental conditions in spring during hatching vary spatially from year to year.…”

Section: Discussionsupporting

confidence: 79%

Dispersion of vendace eggs and larvae around potential nursery areas reveals their reproductive strategy

et al. 2019

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Depending on their reproductive strategy, different fish species aim to aggregate or disperse eggs and larvae in their reproductive habitat. Many pelagic species disperse their eggs widely around the potential nursery areas. Larval dispersion or aggregation affects population sub‐structuring, which has important implications in fisheries management and conservation of the natural spatial diversity in populations. The dispersion of larval vendace (Coregonus albula) was quantified in two oligotrophic Finnish lakes, and effects of density and environmental variables on the inter‐annual variation in the larval distribution were examined by analysing spatial abundance data from the lakes from 1999 to 2017. A 3‐D hydrodynamic egg distribution model was used to simulate the larval transport after hatching. Vendace larvae dispersed lake‐wide to both littoral and pelagic zones but, in some littoral hot spots, more larvae aggregated year after year. However, in years of high larval number, the densities increased not only in the hot spots, but generally at all sampling plots. An overall increase in abundance was observed at all sampling sites. The simulations of the egg distribution model supported the hypothesis that the dispersion of the eggs occurs by spawners, i.e. by spawning at several different spawning sites, which are located all around the lake. The dispersion of vendace eggs and larvae can be seen as a bet‐hedging strategy in space and time since in boreal oligotrophic large lakes with fragmented morphology, weather and other environmental factors in spring during hatching varies from year to year spatially in unpredictable manner. Lake‐wide larval dispersion suggests that the subpopulations of adjacent lake deeps may swap considerable amounts of individuals during early life and may not be closed units. Conservation of particular habitats seems unnecessary for Finnish vendace populations where large potential spawning areas in lakes are available.

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Section: Discussionsupporting

confidence: 79%

Dispersion of vendace eggs and larvae around potential nursery areas reveals their reproductive strategy

et al. 2019

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“…These identify the “grain” of the environmental variation as a strong determinant of whether bet‐hedging strategies will evolve (Crowley et al. ; Starrfelt and Kokko ). If individuals in a population experience very different environments (i.e., the environment is “fine‐grained” or “locally variable”), the fitness correlations between individuals of the same genotype will be low and the scope for DBH is reduced.…”

Section: Discussionmentioning

confidence: 99%

“…Despite this, neither Starrfelt and Kokko () nor later authors exploring similar models (e.g., Crowley et al. ) explain how such a combination of DBH and CBH would work. These papers examine models with two discrete environments, and a suggested conservative bet‐hedger (acting as a generalist coping moderately well with both environments) is never able to outperform a diversified bet‐hedger (producing specialists to each environment in the proportions that they occur).…”

mentioning

confidence: 94%

“…However, there is nothing stopping a strategy from combining the two types, and Starrfelt and Kokko (2012) argue that DBH, reducing only among-individual fitness variance, and CBH, reducing only each individual's fitness variance, are actually two ends of a continuum with strategic combination of DBH and CBH possible in between. Despite this, neither Starrfelt and Kokko (2012) nor later authors exploring similar models (e.g., Crowley et al 2016) explain how such a combination of DBH and CBH would work. These papers examine models with two discrete environments, and a suggested conservative bet-hedger (acting as a generalist coping moderately well with both environments) is never able to outperform a diversified bet-hedger (producing specialists to each environment in the proportions that they occur).…”

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confidence: 95%

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Short‐term insurance versus long‐term bet‐hedging strategies as adaptations to variable environments

et al. 2018

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Understanding how organisms adapt to environmental variation is a key challenge of biology. Central to this are bet‐hedging strategies that maximize geometric mean fitness across generations, either by being conservative or diversifying phenotypes. Theoretical models have identified environmental variation across generations with multiplicative fitness effects as driving the evolution of bet‐hedging. However, behavioral ecology has revealed adaptive responses to additive fitness effects of environmental variation within lifetimes, either through insurance or risk‐sensitive strategies. Here, we explore whether the effects of adaptive insurance interact with the evolution of bet‐hedging by varying the position and skew of both arithmetic and geometric mean fitness functions. We find that insurance causes the optimal phenotype to shift from the peak to down the less steeply decreasing side of the fitness function, and that conservative bet‐hedging produces an additional shift on top of this, which decreases as adaptive phenotypic variation from diversifying bet‐hedging increases. When diversifying bet‐hedging is not an option, environmental canalization to reduce phenotypic variation is almost always favored, except where the tails of the fitness function are steeply convex and produce a novel risk‐sensitive increase in phenotypic variance akin to diversifying bet‐hedging. Importantly, using skewed fitness functions, we provide the first model that explicitly addresses how conservative and diversifying bet‐hedging strategies might coexist.

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“…Both strategies are apparently suboptimal under the averaged environmental conditions but increase the long‐term population growth rate (Simons ). Despite an existing large body of theoretical literature on the topic (Starrfelt and Kokko , Schreiber , Crowley et al ) since the early development of bet‐hedging theory by Cohen (), empirical evidence of bet hedging is still rare (Simons , García‐Roger et al ).…”

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confidence: 99%

Experimental evolution of bet hedging in rotifer diapause traits as a response to environmental unpredictability

Tarazona

García‐Roger

Carmona

2017

Oikos

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The adaptive response of organisms to unpredictable environments is increasingly recognized as a central topic in fundamental and applied evolutionary ecology. Selection due to environmental unpredictability can act on multiple traits of an organism's life cycle to reduce the impact of high environmental variance. The aim of this research was to study how unpredictability selects for diapause traits: 1) the timing of sex (a proxy of the timing of diapausing egg production), and 2) the diapausing egg hatching fraction (a proxy of diapause duration). We used an experimental evolution approach with the facultative sexual rotifer Brachionus plicatilis. Laboratory populations experiencing two contrasting regimes of environmental fluctuation (predictable versus unpredictable) evolved divergently over a short time span (< 77 days). The populations under the unpredictable regime showed an earlier initiation of sexual reproduction and a lower hatching fraction of diapausing eggs than populations under the predictable regime. These findings demonstrate empirically the existence of bet‐hedging strategies in B. plicatilis regarding both traits, consistent with theoretical predictions of bet‐hedging evolution under conditions of unpredictable environmental variance. Given that scenarios of increased environmental variability are expected to occur in the near future, a comprehensive understanding of the role of bet‐hedging strategies is necessary for predicting population responses to environmental change.

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Dealing with stochastic environmental variation in space and time: bet hedging by generalist, specialist, and diversified strategies

Cited by 26 publications

References 27 publications

Dispersion of vendace eggs and larvae around potential nursery areas reveals their reproductive strategy

Dispersion of vendace eggs and larvae around potential nursery areas reveals their reproductive strategy

Short‐term insurance versus long‐term bet‐hedging strategies as adaptations to variable environments

Experimental evolution of bet hedging in rotifer diapause traits as a response to environmental unpredictability

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