Luis Abdala-Roberts1, Sergio Rasmann2, Jorge C Berny-Mier Y Terán3, Felisa Covelo4, Gaétan Glauser5, Xoaquín Moreira6. 1. Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Apartado Postal 4-116, Itzimná. 97000. Mérida, Yucatán, México. 2. Institute of Biology, Laboratory of Functional Ecology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland. 3. Department of Plant Sciences, University of California-Davis, One Shields Avenue, Davis, California, USA 95616. 4. Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Carretera de Utrera km. 1 41013 Sevilla, Spain. 5. Neuchâtel Platform of Analytical Chemistry, University of Neuchâtel, Rue Emile Argand 11, 2000 Neuchâtel, Switzerland. 6. Misión Biológica de Galicia (MBG-CSIC), Apdo. 28 36080 Pontevedra, Galicia, Spain xmoreira1@gmail.com.
Abstract
PREMISE OF THE STUDY: It is generally thought that herbivore pressure is higher at lower elevations where climate is warmer and less seasonal, and that this has led to higher levels of plant defense investment at low elevations. However, the generality of this expectation has been called into question by recent studies. METHODS: We tested for altitudinal gradients in insect leaf damage, plant defenses (phenolic compounds), and nutritional traits (phosphorus and nitrogen) in leaves of the long-lived tree Quercus robur, and further investigated the abiotic factors associated with such gradients. We sampled 20 populations of Q. robur distributed along an altitudinal gradient spanning 35-869 m above sea level, which covered most of the altitudinal range of this species and varied substantially in abiotic conditions, plant traits, and herbivory. KEY RESULTS: Univariate regressions showed that leaf herbivory, phenolics, and phosphorus increased toward higher elevations, whereas leaf nitrogen did not vary with altitude. Multiple regression analyses indicated that temperature was the single most important factor associated with herbivory and appears to be strongly associated with altitudinal variation in damage. Leaf phenolics were also correlated with herbivory, but in a manner that suggests these chemical defenses do not underlie altitudinal variation in damage. In addition, we found that variation in leaf traits (phenolics and nutrients) was in turn associated with both climatic and soil variables. CONCLUSIONS: Overall, these findings suggest that altitudinal gradients in herbivory and defenses in Q. robur are uncoupled and that elevational variation in herbivory and plant traits responds mainly to abiotic factors.
PREMISE OF THE STUDY: It is generally thought that herbivore pressure is higher at lower elevations where climate is warmer and less seasonal, and that this has led to higher levels of plant defense investment at low elevations. However, the generality of this expectation has been called into question by recent studies. METHODS: We tested for altitudinal gradients in insect leaf damage, plant defenses (phenolic compounds), and nutritional traits (phosphorus and nitrogen) in leaves of the long-lived tree Quercus robur, and further investigated the abiotic factors associated with such gradients. We sampled 20 populations of Q. robur distributed along an altitudinal gradient spanning 35-869 m above sea level, which covered most of the altitudinal range of this species and varied substantially in abiotic conditions, plant traits, and herbivory. KEY RESULTS: Univariate regressions showed that leaf herbivory, phenolics, and phosphorus increased toward higher elevations, whereas leaf nitrogen did not vary with altitude. Multiple regression analyses indicated that temperature was the single most important factor associated with herbivory and appears to be strongly associated with altitudinal variation in damage. Leaf phenolics were also correlated with herbivory, but in a manner that suggests these chemical defenses do not underlie altitudinal variation in damage. In addition, we found that variation in leaf traits (phenolics and nutrients) was in turn associated with both climatic and soil variables. CONCLUSIONS: Overall, these findings suggest that altitudinal gradients in herbivory and defenses in Q. robur are uncoupled and that elevational variation in herbivory and plant traits responds mainly to abiotic factors.
Authors: Xoaquín Moreira; Luis Abdala-Roberts; Hans Henrik Bruun; Felisa Covelo; Pieter De Frenne; Andrea Galmán; Álvaro Gaytán; Raimo Jaatinen; Pertti Pulkkinen; Jan P J G Ten Hoopen; Bart G H Timmermans; Ayco J M Tack; Bastien Castagneyrol Journal: Ann Bot Date: 2020-05-13 Impact factor: 4.357
Authors: Jarmo K Holopainen; Virpi Virjamo; Rajendra P Ghimire; James D Blande; Riitta Julkunen-Tiitto; Minna Kivimäenpää Journal: Front Plant Sci Date: 2018-10-02 Impact factor: 5.753