Simulated herbivory does not constrain phenotypic plasticity to shade through ontogeny in a relict tree

Abstract

Ecological limits to phenotypic plasticity (PP), induced by simultaneous biotic and abiotic factors, can prevent organisms from exhibiting optimal plasticity, and in turn lead to decreased fitness. Herbivory is an important biotic stressor and may limit plant functional responses to challenging environmental conditions such as shading. In this study we investigated whether plant functional responses and PP to shade are constrained by herbivory, and whether such constraints are due to direct effects based on resource limitation by considering ontogeny. We used as a model system the relict tree Prunus lusitanica and implemented an indoor experiment to quantify the response of saplings of different ages to shade and herbivory. We measured five functional traits and quantitatively calculated PP. Results showed that herbivory did not constrain functional responses or PP to shade except for shoot:root ratio (SR), which, despite showing a high PP in damaged saplings, decreased under shade instead of increasing. Damaged saplings of older age did not exhibit reduced constraints on functional responses to shade and generally presented a lower PP than damaged saplings of younger age. Our findings suggest that herbivory-mediated constraints on plant plasticity to shade may not be as widespread as previously thought. Nonetheless, the negative effect of herbivory on SR plastic expression to shade could be detrimental for plant fitness. Finally, our results suggest a secondary role of direct effects (resource-based) on P. lusitanica plasticity limitation. Further studies should quantify plant resources in order to gain a better understanding of this seldom-explored subject.

Improvement in light utilization and shoot growth in Hymenaea stigonocarpa under high CO 2 concentration attenuates simulated leaf herbivory effects

“…Simulated herbivory has been intensely utilized to determine likely herbivory effects on plant growth, biomass partitioning, reproduction and morphology (Camargo et al 2015;Pardo et al 2016;Yamawo et al 2018). Besides, simulated herbivory contributes to obtaining physiological responses of plants after damage and the resultant effects of biotic and abiotic interactions (Tscharntke et al 2001;Scott et al 2019).The increase of F0 in the leaves of plants grown in ambient [CO 2 ] and subjected to simulated herbivory at the basal or apical portion of the stem is possibly related to the existence of damage at the PSII reaction center or to the reduction of energy transfer capacity of excitation from the light collecting system to the reaction center (Baker & Rosenqvist 2004).…”

Efeitos da herbivoria e condições ambientais sobre a instabilidade no desenvolvimento e resposta vegetativa em Tithonia diversifolia (Asteraceae)

“…A ausência de alteração em defesas antiherbivoria na condição de competição edáfica juntamente com a herbivoria possivelmente ocorreu pelas variáveis analisadas aqui neste trabalho (clorofila e esclerofilia) não serem tipos de defesas antiherbivoria presente nessa espécie (Hanley et al 2007;Ambrósio et al 2008). Por fim, a ausência do aumento dos impactos negativos da associação da herbivoria com sombreamento e da herbivoria com competição edáfica em T. diversifolia, pode indicar que essa espécie possui tolerância a associação de mais de um fator negativo por esses não terem sido tão intensos ao ponto impactá-la severamente (Wise & Abrahamson 2007;Pardo et al 2016).…”