LIFE-HISTORY RESPONSES TO VARIABLE ENVIRONMENTS: STARVATION AND REPRODUCTION IN PLANKTONIC ROTIFERS

Ecology ◽  
1997 ◽  
Vol 78 (2) ◽  
pp. 434-441 ◽  
Author(s):  
Kevin L. Kirk
1990 ◽  
Vol 28 (1-4) ◽  
pp. 77-85 ◽  
Author(s):  
Michael J. Armstrong ◽  
Peter A. Shelton

2021 ◽  
Author(s):  
Flor T. Rhebergen ◽  
Isabel M. Smallegange

The timing of maturation, a critical fitness determinant, is influenced by developmental and energetic constraints, particularly when growth is poor in adverse conditions. Such constraints can be altered through developmental plasticity. Thus, in theory, plasticity in energetically costly sexually selected morphologies can promote life history flexibility in variable environments. We experimentally tested this hypothesis in bulb mites (Rhizoglyphus robini) that polyphenically develop as armed fighters with enlarged legs or as scramblers without modified legs. We found that (i) mites enter metamorphosis earlier if they develop as scramblers, (ii) mites accelerate the onset of metamorphosis when they sense resource limitation, and (iii) scrambler expression increases under increased competition for food, enabling males to mature early and escape juvenile mortality. We propose that life history plasticity can evolve through polyphenic release from sexually selected constraints, making the evolutionary dynamics of secondary sexual traits and life history traits, typically studied separately, interdependent.


2018 ◽  
Author(s):  
Cristina Acasuso-Rivero ◽  
Courtney J. Murren ◽  
Carl D. Schlichting ◽  
Ulrich K. Steiner

ABSTRACTOrganisms are faced with variable environments and one of the most common solutions to cope with such variability is phenotypic plasticity, a modification of the phenotype to the environment. These modifications influence ecological and evolutionary processes and are assumed to be adaptive. The assumption of adaptive plasticity allows to derive the prediction that the closer to fitness a trait is, the less plastic it would be. To test this hypothesis, we conducted a meta-analysis of 213 studies and measured the plasticity of each reported trait as coefficient of variation (CV). Traits were categorised according to their relationship to fitness into life-history traits (LHt) including reproduction and survival related-traits, and non-life-history traits (N-LHt) including traits related to development, metabolism and physiology, morphology and behaviour. Our results showed, unexpectedly, that although traits differed in their amounts of plasticity, trait plasticity did not correlate with its proximity to fitness. These findings were independent of taxonomic groups or environmental types assessed and raise questions about the ubiquity of adaptive plasticity. We caution about generalising the assumption that all plasticity is adaptive with respect to evolutionary and ecological population processes. More studies are needed that test the adaptive nature of plasticity, and additional theoretical explorations on adaptive and non-adaptive plasticity are encouraged.


2019 ◽  
Vol 286 (1904) ◽  
pp. 20190653 ◽  
Author(s):  
Cristina Acasuso-Rivero ◽  
Courtney J. Murren ◽  
Carl D. Schlichting ◽  
Ulrich K. Steiner

Organisms are faced with variable environments and one of the most common solutions to cope with such variability is phenotypic plasticity, a modification of the phenotype to the environment. These modifications are commonly modelled in evolutionary theories as adaptive, influencing ecological and evolutionary processes. If plasticity is adaptive, we would predict that the closer to fitness a trait is, the less plastic it would be. To test this hypothesis, we conducted a meta-analysis of 213 studies and measured the plasticity of each reported trait as a coefficient of variation. Traits were categorized as closer to fitness—life-history traits including reproduction and survival related traits, and farther from fitness—non-life-history traits including traits related to development, metabolism and physiology, morphology and behaviour. Our results showed, unexpectedly, that although traits differed in their amounts of plasticity, trait plasticity was not related to its proximity to fitness. These findings were independent of taxonomic groups or environmental types assessed. We caution against general expectations that plasticity is adaptive, as assumed by many models of its evolution. More studies are needed that test the adaptive nature of plasticity, and additional theoretical explorations on adaptive and non-adaptive plasticity are encouraged.


2021 ◽  
Author(s):  
Christie Le Coeur ◽  
Nigel Gilles Yoccoz ◽  
Roberto Salguero-Gomez ◽  
Yngvild Vindenes

Demographic buffering and lability have both been identified as important adaptive strategies to optimise long-term fitness in variable environments. These strategies are not mutually exclusive, however we lack efficient methods to measure their relative importance. Here, we define a new index to measure the total lability for a given life history, and use stochastic simulations to disentangle relative fitness effects of buffering and lability. The simulations use 81 animal matrix population models, and different scenarios to explore how the strategies vary across life histories. The highest potential for adaptive demographic lability was found for short- to intermediately long-lived species, while demographic buffering was the main response in slow-living species. This study suggests that faster-living species are more responsive to environmental variability, both for positive or negative effects. Our methods and results provide a more comprehensive view of adaptations to variability, of high relevance to predict species responses to climate change.


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