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

Clauss, Maria J.; Venable, D. Lawrence

doi:10.1086/303314

Cited by 277 publications

(291 citation statements)

References 39 publications

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“…This work joins a limited number of empirical studies demonstrating mixed strategy usage. These studies have focused mostly on dormancy emergence traits, such as seed germination timing in desert annuals [26] and diapause break in killifish [12]. Our study suggests that mixed strategies may also be common in dispersal traits, such as previously shown in an amphicarpic annual plant [27] and now in the pea aphid wing polyphenism.…”

Section: Discussionsupporting

confidence: 64%

A case for a joint strategy of diversified bet hedging and plasticity in the pea aphid wing polyphenism

Grantham¹,

Antonio²,

O'Neil³

et al. 2016

Biol. Lett.

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Phenotypic plasticity and diversified bet hedging are strategies for coping with variable environments. Plasticity is favoured when an organism can predict future conditions using environmental cues, while bet hedging is favoured when predictive cues are not available. Theoretical analyses suggest that many organisms should use a mixture of both strategies, because environments often present both scenarios. Here, we examine if the pea aphid wing polyphenism, a well-known case of plasticity, is potentially a mixture of plasticity and bet hedging. In this polyphenism, asexual females produce more winged offspring in crowded conditions, and wingless offspring in uncrowded conditions. We find that pea aphids use plasticity to respond to crowding and we find considerable genetic variation for this response. We further show that individual aphids produce both winged and wingless offspring, consistent with the variability expected in a bet hedging trait. We conclude that the pea aphid wing polyphenism system is probably a mixture of plasticity and bet hedging. Our study adds to a limited list of empirical studies examining mixed strategy usage, and suggests that mixed strategies may be common in dispersal traits.

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Section: Discussionsupporting

confidence: 64%

A case for a joint strategy of diversified bet hedging and plasticity in the pea aphid wing polyphenism

Grantham¹,

Antonio²,

O'Neil³

et al. 2016

Biol. Lett.

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“…precipitation). Consistent with theory, annual plant populations from drier habitats have been found to exhibit higher seed dormancy [63] and a stronger response to precipitation as a trigger of germination [64], compared with conspecifics from wetter, less variable habitats. In addition, they exhibit a faster life cycle [65] and larger reproductive effort when resources are abundant [30].…”

Section: Precipitation Global Environmental Change and Desert Plantsupporting

confidence: 63%

A demographic approach to study effects of climate change in desert plants

Salguero‐Gómez

Siewert

Casper

et al. 2012

Phil. Trans. R. Soc. B

110

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Desert species respond strongly to infrequent, intense pulses of precipitation. Consequently, indigenous flora has developed a rich repertoire of life-history strategies to deal with fluctuations in resource availability. Examinations of how future climate change will affect the biota often forecast negative impacts, but these-usually correlative-approaches overlook precipitation variation because they are based on averages. Here, we provide an overview of how variable precipitation affects perennial and annual desert plants, and then implement an innovative, mechanistic approach to examine the effects of precipitation on populations of two desert plant species. This approach couples robust climatic projections, including variable precipitation, with stochastic, stage-structured models constructed from long-term demographic datasets of the short-lived Cryptantha flava in the Colorado Plateau Desert (USA) and the annual Carrichtera annua in the Negev Desert (Israel). Our results highlight these populations' potential to buffer future stochastic precipitation. Population growth rates in both species increased under future conditions: wetter, longer growing seasons for Cryptantha and drier years for Carrichtera. We determined that such changes are primarily due to survival and size changes for Cryptantha and the role of seed bank for Carrichtera. Our work suggests that desert plants, and thus the resources they provide, might be more resilient to climate change than previously thought.

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“…Philippi (1993), in a pioneering test, found that seeds not germinating during the first year germinate in subsequent years under the same conditions. Clauss & Venable (2000) showed that the rank order of dormancy fractions among populations closely matches the order predicted by differences in historical rainfall, but that adaptive plasticity was the primary influence on germination fraction. Evans and colleagues (2007) showed convincingly that fluctuating selection favours dormancy over non-dormancy under variably arid conditions.…”

Section: Discussionmentioning

confidence: 65%

Fluctuating natural selection accounts for the evolution of diversification bet hedging

2009

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

Cited by 277 publications

References 39 publications

A case for a joint strategy of diversified bet hedging and plasticity in the pea aphid wing polyphenism

A case for a joint strategy of diversified bet hedging and plasticity in the pea aphid wing polyphenism

A demographic approach to study effects of climate change in desert plants

Fluctuating natural selection accounts for the evolution of diversification bet hedging

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