TY - JOUR

T1 - Variation in nectar quality across 34 grassland plant species

AU - Venjakob, Christine

AU - Ruedenauer, F. A.

AU - Klein, Alexandra-Maria

AU - Leonhardt, Sara D.

N1 - The German Science Foundation (DFG) funded the Jena Experiment (DFG-FOR 1451/2) and SDL (LE 2750/1-1). We thank all members of the Jena Experiment community, who helped in maintaining the experiment throughout many years. Especially, we would like to thank our coordinator Anne Ebeling, our technical assistant Gerlinde Kratzsch and the gardeners, particularly Ute Köber and Silke Hengelhaupt, who also helped with flower bagging. Further thanks go to Stephanie Schröder who helped with nectar sampling. M. Heil and three anonymous reviewers provided useful input on an earlier version of the manuscript. Finally, we gratefully acknowledge Angela Gronert for performing analyses with HPLC and Richard Bolek for his useful advice. Publisher Copyright: © 2021 The Authors. Plant Biology published by John Wiley & Sons Ltd on behalf of German Society for Plant Sciences, Royal Botanical Society of the Netherlands.

PY - 2022/1/1

Y1 - 2022/1/1

N2 - Floral nectar is considered the most important floral reward for attracting pollinators. It contains large amounts of carbohydrates besides variable concentrations of amino acids and thus represents an important food source for many pollinators. Its nutrient content and composition can, however, strongly vary within and between plant species. The factors driving this variation in nectar quality are still largely unclear. We investigated factors underlying interspecific variation in macronutrient composition of floral nectar in 34 different grassland plant species. Specifically, we tested for correlations between the phylogenetic relatedness and morphology of plants and the carbohydrate (C) and total amino acid (AA) composition and C:AA ratios of nectar. We found that compositions of carbohydrates and (essential) amino acids as well as C:AA ratios in nectar varied significantly within and between plant species. They showed no clear phylogenetic signal. Moreover, variation in carbohydrate composition was related to family-specific structural characteristics and combinations of morphological traits. Plants with nectar-exposing flowers, bowl- or parabolic-shaped flowers, as often found in the Apiaceae and Asteraceae, had nectar with higher proportions of hexoses, indicating a selective pressure to decelerate evaporation by increasing nectar osmolality. Our study suggests that variation in nectar nutrient composition is, among others, affected by family-specific combinations of morphological traits. However, even within species, variation in nectar quality is high. As nectar quality can strongly affect visitation patterns of pollinators and thus pollination success, this intra- and interspecific variation requires more studies to fully elucidate the underlying causes and the consequences for pollinator behaviour.

AB - Floral nectar is considered the most important floral reward for attracting pollinators. It contains large amounts of carbohydrates besides variable concentrations of amino acids and thus represents an important food source for many pollinators. Its nutrient content and composition can, however, strongly vary within and between plant species. The factors driving this variation in nectar quality are still largely unclear. We investigated factors underlying interspecific variation in macronutrient composition of floral nectar in 34 different grassland plant species. Specifically, we tested for correlations between the phylogenetic relatedness and morphology of plants and the carbohydrate (C) and total amino acid (AA) composition and C:AA ratios of nectar. We found that compositions of carbohydrates and (essential) amino acids as well as C:AA ratios in nectar varied significantly within and between plant species. They showed no clear phylogenetic signal. Moreover, variation in carbohydrate composition was related to family-specific structural characteristics and combinations of morphological traits. Plants with nectar-exposing flowers, bowl- or parabolic-shaped flowers, as often found in the Apiaceae and Asteraceae, had nectar with higher proportions of hexoses, indicating a selective pressure to decelerate evaporation by increasing nectar osmolality. Our study suggests that variation in nectar nutrient composition is, among others, affected by family-specific combinations of morphological traits. However, even within species, variation in nectar quality is high. As nectar quality can strongly affect visitation patterns of pollinators and thus pollination success, this intra- and interspecific variation requires more studies to fully elucidate the underlying causes and the consequences for pollinator behaviour.

KW - Flower morphology

KW - flowering grassland plants

KW - Jena Experiment

KW - nectar macronutrients

KW - phylogeny

KW - Ecosystems Research

UR - http://www.scopus.com/inward/record.url?scp=85116457419&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/4a9eb6a7-06e5-3cbf-92d7-ab6d6f60b26c/

U2 - 10.1111/plb.13343

DO - 10.1111/plb.13343

M3 - Journal articles

C2 - 34618397

AN - SCOPUS:85116457419

VL - 24

SP - 134

EP - 144

JO - Plant Biology

JF - Plant Biology

SN - 1435-8603

IS - 1

ER -