“Transgenerational and within-generation plasticity in response to climate change: insights from a manipulative field experiment across an elevational gradient”

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Susana M. Wadgymar, Rachel M. Mactavish, and Jill T. Anderson (Dec 2018)

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Transgenerational and within-generation plasticity interact and vary clinally in populations across elevation gradients

A view of Mt. Crested Butte from our low elevation garden (elevation: 2710 m) after snow removal but before snowmelt (April 2016). PVC poles mark out the locations of the plots.
(Credit: Susana M. Wadgymar)

Environmental conditions strongly influence an individual’s phenotype and fitness. Temporal and spatial variation in the landscape can favor the evolution of phenotypic plasticity, such that one individual can produce different phenotypes depending on the environment it encounters. However, we know very little about the extent to which the environment a parent experiences affects the phenotypes of the offspring, and whether phenotypic plasticity across generations interacts with plasticity that arises within generations. Given the importance of environmental variation in the evolution of plasticity, populations distributed across gradients may have evolved different strategies for responding to changes in the environment. Studies of transgenerational and within-generation plasticity can reveal potential mechanisms through which populations or species could mitigate the effects of rapid climate change.

Here, Wadgymar, MacTavish, and Anderson examine transgenerational and within-generation plasticity in life history traits in response to climate change in sixteen populations of the perennial forb, Boechera stricta (Drummond’s rockcress, in the Brassicaceae) distributed across an elevational gradient in the Rocky Mountains of Colorado. In the field, the researchers manipulated snowpack and the timing of snowmelt in a two-generation reciprocal transplant experiment conducted in three common gardens established near the lower, intermediate, and higher range boundaries of Boechera’s distribution in this region. In the greenhouse, they exposed plants to conditions simulating high and low elevation sites.

Susana Wadgymar planting seeds into a grid in a high elevation experimental garden.
(Credit: Jill T. Anderson)

In the field, the scientists discovered that transgenerational plasticity in seed mass, seed dormancy, and seedling emergence varied clinally across an elevational gradient and differed between snow-removal and control treatments. The arid and warm conditions typical of low-elevation sites and the researchers’ snow-removal treatment caused plants to produce smaller and more dormant seeds in comparison to the less-arid, cooler conditions typical of high-elevation sites and the control treatment. Small seeds had a greater probability of being non-viable, and low-elevation genotypes produce smaller seeds than high-elevation genotypes. Altogether, these results suggest that climate change may have disproportionately negative consequences for low-elevation populations, and that these effects are mediated, in part, by transgenerational plasticity. The results demonstrate that the effects of climate change on transgenerational plasticity are complex and context-dependent. The researchers propose that future studies should incorporate the influence of parental effects in studies of climate change, adaptation, and species persistence.


A seed grid with several older Boechera stricta seedlings that have developed 4 true leaves while retaining their cotyledons.
(Credit: Jill T. Anderson)

Abstract

Parental environmental effects, or transgenerational plasticity, can influence an individual’s phenotype or fitness, yet remain underexplored in the context of global change. Using the perennial self-pollinating plant Boechera stricta, we explored the effects of climate change on transgenerational and within-generation plasticity in dormancy, germination, growth, and survival. We first conducted a snow removal experiment in the field, in which we transplanted 16 families of known origin into three common gardens at different elevations and exposed half of the siblings to contemporary snow dynamics and half to early snow removal. We planted the offspring of these individuals in a factorial manipulation of temperature and water level in the growth chamber, and reciprocally transplanted them across all parental environments in the field. The growth chamber experiment revealed that the effects of transgenerational plasticity persist in traits expressed after establishment, even when accounting for parental effects on seed mass. The field experiment showed that transgenerational and within-generation plasticity can interact and that plasticity varies clinally in populations distributed across elevations. These findings demonstrate that transgenerational plasticity can influence fitness-related traits and should be incorporated in studies of biological responses to climate change.

Plasticidad transgeneracional e intrageneracional en respuesta a los cambios climáticos: Resultados de un experimento de campo manipulativo a través de un gradiente de elevación

Los efectos ambientales parentales, o la plasticidad transgeneracional, pueden influir en el fenotipo y la adecuación (fitness) de un individuo, pero permanecen poco estudiados en el contexto de los cambios climáticos. Utilizando la planta perenne y de autofecundación, Boechera stricta, exploramos los efectos del cambio climático sobre la plasticidad transgeneracional e intrageneracional en la dormancia, la germinación, el crecimiento y la supervivencia. Primero realizamos un experimento de remoción de la nieve en el campo, en el que trasplantamos 16 familias de origen conocido en tres jardines comunes a diferentes elevaciones. Expusimos la mitad de los individuos a las dinámicas contemporáneas de nieve y la otra mitad a la eliminación temprana de la nieve. Plantamos a los descendientes de estos individuos siguiendo una manipulación factorial de temperatura y nivel de agua en el laboratorio, y los trasplantamos recíprocamente a través de todos los ambientes paternales en el campo. El experimento controlado en el laboratorio reveló que los efectos de la plasticidad transgeneracional persisten en rasgos expresados después del establecimiento, incluso cuando se contabilizan los efectos paternos en el peso de la semilla. El experimento de campo mostró que la plasticidad transgeneracional e intrageneracional pueden interactuar y que la plasticidad varía de forma clinal en las poblaciones distribuidas a través de las elevaciones. Estos hallazgos demuestran que la plasticidad transgeneracional puede influir en los rasgos relacionados con la adecuación y debe ser incorporada en estudios de respuestas biológicas al cambio climático.