Latitudinal variation in soil biota: testing the biotic interaction hypothesis with an invasive plant and a native congener

Minyan He,Jianqing Ding,Xinmin Lu,Evan Siemann

doi:10.1038/s41396-018-0219-5

Abstract

Soil biota community structure can change with latitude, but the effects of changes on native plants, invasive plants, and their herbivores remain unclear. Here, we examined latitudinal variation in the soil biota community associated with the invasive plant Alternanthera philoxeroides and its native congener A. sessilis, and the effects of soil biota community variation on these plants and the beetle Agasicles hygrophila. We characterized the soil bacterial and fungal communities and root-knot nematodes of plant rhizospheres collected from 22 °N to 36.6 °N in China. Soil biota community structure changed with latitude as a function of climate and soil properties. Root-knot nematode abundance and potential soil fungal pathogen diversity (classified with FUNGuild) decreased with latitude, apparently due to higher soil pH and lower temperatures. A greenhouse experiment and lab bioassay showed native plant mass, seed production, and mass of beetles fed native foliage increased with soil collection latitude. However, there were no latitudinal patterns for the invasive plant. These results suggest that invasive and native plants and, consequently, their herbivores have different responses to latitudinal changes in soil-borne enemies, potentially creating spatial variation in enemy release or biotic resistance. This highlights the importance of linking above- and below-ground multitrophic interactions to explore the role of soil biota in non-native plant invasions with a biogeographic approach.

Highlights

IntroductionThe Latitudinal Biotic Interaction Hypothesis posits that biotic interactions are more intense at low than at high latitudes because a more benign climate and higher species diversity at low latitudes lead to stronger interactions [5, 6]
Biotic interactions can influence species distribution, community structure, and non-native species invasions [1, 2].These authors contributed : Xinmin Lu, Minyan He.Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Understanding how biotic interactions respond to environmental changes is critical for the current and future conservation of biodiversity [3]
Soil pH increased by 16.5% along the latitudinal gradient (F1, 29 = 12.96, P = 0.0012, f2 = 0.463) but the rate of increase did not differ between soil types (Supplementary Table S2 and Supplementary Fig. S2)

Summary

Introduction

The Latitudinal Biotic Interaction Hypothesis posits that biotic interactions are more intense at low than at high latitudes because a more benign climate and higher species diversity at low latitudes lead to stronger interactions [5, 6] This theory has been tested extensively on antagonistic and mutualistic interactions between native species, with many studies showing higher levels of herbivory, predation, or parasitism at low than at high latitudes [5, 7]; other studies have found no such pattern [8, 9]. Most of these studies have emphasized above-ground interactions, largely overlooking plant–soil biota interactions and the indirect, plant-mediated impacts of soil biota on above-ground herbivores [5, 8, 9]

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Results

Conclusion