Selective Pressure along a Latitudinal Gradient Affects Subindividual Variation in Plants

Mar Sobral,José Guitián,Pablo Guitián,Asier R Larrinaga,Gabriele Sorci

doi:10.1371/journal.pone.0074356

Abstract

Individual plants produce repeated structures such as leaves, flowers or fruits, which, although belonging to the same genotype, are not phenotypically identical. Such subindividual variation reflects the potential of individual genotypes to vary with micro-environmental conditions. Furthermore, variation in organ traits imposes costs to foraging animals such as time, energy and increased predation risk. Therefore, animals that interact with plants may respond to this variation and affect plant fitness. Thus, phenotypic variation within an individual plant could be, in part, an adaptive trait. Here we investigated this idea and we found that subindividual variation of fruit size of Crataegus monogyna, in different populations throughout the latitudinal gradient in Europe, was explained at some extent by the selective pressures exerted by seed-dispersing birds. These findings support the hypothesis that within-individual variation in plants is an adaptive trait selected by interacting animals which may have important implications for plant evolution.

Highlights

Meaningful variation in nature ranges from the level of individuals up to the scale of biomes
To study the effect that selective pressures exerted by seeddispersing birds may have on the variation of fruit size in hawthorn, we examined the differences in within-individual variation among populations, across the latitudinal range of distribution in Europe, and we determined the factors affecting them, teasing apart the effect of selective pressures exerted by the seed-dispersing birds from other factors
The results of this research, despite admittedly correlative, show that differences in the subindividual variation of fruit size among different hawthorn populations throughout its latitudinal range of distribution were partly explained by the selective pressures exerted by seed-dispersing birds at each population

Summary

Introduction

Meaningful variation in nature ranges from the level of individuals up to the scale of biomes. Natural selection acts on phenotypes and a single individual (genotype) can produce a set of different phenotypes depending on the environmental conditions, a process known as phenotypic plasticity Modular organisms, such as plants, produce a multiplicity of repeated structures like leaves, flowers and fruits which are phenotypically different and can be considered ‘‘re-runs’’ of the same genotype under different internal and external microenvironmental conditions [1]. Subindividual variation, the phenotypic variation among repeated organs within the same individual, is caused by a complex web of factors including ontogenetic contingency, organlevel reaction norms and developmental instability. One component of variation within individuals that may have a genetic basis and could be affected by natural selection is organ-level reaction norms, which cause organlevel phenotypic plasticity [1]. We explore here the potential evolutionary implications of subindividual variation in plant phenotypic traits

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Conclusion