An official website of the United States government
Abstract Actuarial senescence (called ‘senescence’ hereafter) often shows broad variation at the intraspecific level. Phenotypic plasticity likely plays a central role in among‐individual heterogeneity in senescence rate (i.e. the rate of increase in mortality with age), although our knowledge on this subject is still very fragmentary. Polyphenism—the unique sub‐type of phenotypic plasticity where several discrete phenotypes are produced by the same genotype—may provide excellent study systems to investigate if and how plasticity affects the rate of senescence in nature.In this study, we investigated whether facultative paedomorphosis influences the rate of senescence in a salamander,Ambystoma mavortium nebulosum. Facultative paedomorphosis, a unique form of polyphenism found in dozens of urodele species worldwide, leads to the production of two discrete, environmentally induced phenotypes: metamorphic and paedomorphic individuals. We leveraged an extensive set of capture–recapture data (8948 individuals, 24 years of monitoring) that were analysed using multistate capture–recapture models and Bayesian age‐dependent survival models.Multistate models revealed that paedomorphosis was the most common developmental pathway used by salamanders in our study system. Bayesian age‐dependent survival models then showed that paedomorphs have accelerated senescence in both sexes and shorter adult lifespan (in females only) compared to metamorphs. In paedomorphs, senescence rate and adult lifespan also varied among ponds and individuals. Females with good body condition and high lifetime reproductive success had slower senescence and longer lifespan. Late‐breeding females also lived longer but showed a senescence rate similar to that of early‐breeding females. Moreover, males with good condition had longer lifespan than males with poor body condition, although they had similar senescence rates. In addition, late‐breeding males lived longer but, unexpectedly, had higher senescence than early‐breeding males.Overall, our work provides one of the few empirical cases suggesting that environmentally cued polyphenism could affect the senescence of a vertebrate in nature, thus providing insights on the ecological and evolutionary consequences of developmental plasticity on ageing.
more »
« less
Vegetative phase change causes age‐dependent changes in phenotypic plasticity
Summary Phenotypic plasticity allows organisms to optimize traits for their environment. As organisms age, they experience diverse environments that benefit from varying degrees of phenotypic plasticity. Developmental transitions can control these age‐dependent changes in plasticity, and as such, the timing of these transitions can determine when plasticity changes in an organism.Here, we investigate how the transition from juvenile‐to adult‐vegetative development known as vegetative phase change (VPC) contributes to age‐dependent changes in phenotypic plasticity and how the timing of this transition responds to environment using both natural accessions and mutant lines in the model plantArabidopsis thaliana.We found that the adult phase of vegetative development has greater plasticity in leaf morphology than the juvenile phase and confirmed that this difference in plasticity is caused by VPC using mutant lines. Furthermore, we found that the timing of VPC, and therefore the time when increased plasticity is acquired, varies significantly across genotypes and environments.The consistent age‐dependent changes in plasticity caused by VPC suggest that VPC may be adaptive. This genetic and environmental variation in the timing of VPC indicates the potential for population‐level adaptive evolution of VPC.
more »
« less
- PAR ID:
- 10487681
- Publisher / Repository:
- New Phytologist
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 240
- Issue:
- 2
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- 613 to 625
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Polyphenisms occur when phenotypic plasticity produces morphologically distinct phenotypes from the same genotype. Plasticity is maintained through fitness trade‐offs which are conferred to different phenotypes under specific environmental contexts. Predicting the impacts of contemporary climate change on phenotypic plasticity is critical for climate‐sensitive animals like amphibians, but elucidating the selective pressures maintaining polyphenisms requires a framework to control for all mechanistic drivers of plasticity.Using a 32‐year dataset documenting the larval and adult histories of 717 Arizona tiger salamanders (Ambystoma mavortium nebulosum), we determined how annual variation in climate and density dependence explained the maintenance of two distinct morphs (terrestrial metamorph vs. aquatic paedomorph) in a high‐elevation polyphenism. The effects of climate and conspecific density on morph development were evaluated with piecewise structural equation models (SEM) to tease apart the direct and indirect pathways by which these two mechanisms affect phenotypic plasticity.Climate had a direct effect on morph outcome whereby longer growing seasons favoured metamorphic outcomes. Also, climate had indirect effects on morph outcome as mediated through density‐dependent effects, such as long overwintering coldspells corresponding to high cannibal densities and light snowpacks corresponding to high larval densities, both of which promoted paedomorphic outcomes.Both climate and density dependence serve as important proxies for growth and resource limitation, which are important underlying drivers of the phenotypic plasticity in animal polyphenisms. Our findings motivate new studies to determine how contemporary climate change will alter the selective pressures maintaining phenotypic plasticity and polyphenisms.more » « less
-
Abstract Plant functional strategies change considerably as plants develop, driven by intraindividual variability in anatomical, morphological, physiological and architectural traits.Developmental trait variation arises through the complex interplay among genetically regulated phase change (i.e. ontogeny), increases in plant age and size, and phenotypic plasticity to changing environmental conditions. Although spatial drivers of intraspecific trait variation have received extensive research attention, developmentally driven intraspecific trait variation is largely overlooked, despite widespread occurrence.Ontogenetic trait variation is genetically regulated, leads to dramatic changes in plant phenotypes and evolves in response to predictable changes in environmental conditions as plants develop.Evidence has accumulated to support a general shift from fast to slow relative growth rates and from shade to sun leaves as plants develop from the highly competitive but shady juvenile niche to the stressful adult niche in the systems studied to date.Nonetheless, there are major gaps in our knowledge due to examination of only a few environmental factors selecting for the evolution of ontogenetic trajectories, variability in how ontogeny is assigned, biogeographic sampling biases on trees in temperate biomes, dependencies on a few broadly sampled leaf morphological traits and a lack of longitudinal studies that track ontogeny within individuals. Filling these gaps will enhance our understanding of plant functional ecology and provide a framework for predicting the effects of global change threats that target specific ontogenetic stages. Read the freePlain Language Summaryfor this article on the Journal blog.more » « less
-
null (Ed.)Vegetative leaves in Arabidopsis are classified as either juvenile leaves or adult leaves based on their specific traits, such as leaf shape and the presence of abaxial trichomes. The timing of the juvenile-to-adult phase transition during vegetative development, called the vegetative phase change, is a critical decision for plants, as this transition is associated with crop yield, stress responses, and immune responses. Juvenile leaves are characterized by high levels of miR156/157, and adult leaves are characterized by high levels of miR156/157 targets, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. The discovery of this miR156/157-SPL module provided a critical tool for elucidating the complex regulation of the juvenile-to-adult phase transition in plants. In this review, we discuss how the traits of juvenile leaves and adult leaves are determined by the miR156/157-SPL module and how different factors, including embryonic regulators, sugar, meristem regulators, hormones, and epigenetic proteins are involved in controlling the juvenile-to-adult phase transition, focusing on recent insights into vegetative phase change. We also highlight outstanding questions in the field that need further investigation. Understanding how vegetative phase change is regulated would provide a basis for manipulating agricultural traits under various conditions.more » « less
-
Correct timing of developmental phase transitions is critical for the survival and fitness of plants. Developmental phase transitions in plants are partially promoted by controlling relevant genes into active or repressive status. Polycomb Repressive Complex1 (PRC1) and PRC2, originally identified in Drosophila, are essential in initiating and/or maintaining genes in repressive status to mediate developmental phase transitions. Our review summarizes mechanisms in which the embryo-to-seedling transition, the juvenile-to-adult transition, and vegetative-to-reproductive transition in plants are mediated by PRC1 and PRC2, and suggests that PRC1 could act either before or after PRC2, or that they could function independently of each other. Details of the exact components of PRC1 and PRC2 in each developmental phase transitions and how they are recruited or removed will need to be addressed in the future.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/nph.19174
