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The structure of legume – rhizobium interaction networks and their response to tree invasions

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ABSTRACT

We provide data on how legume-rhizobia interaction webs react to invasions by exotic legumes. This is the first study of its kind and found that general hypotheses derived from above-ground mutualistic webs may not hold for below-ground counterparts. Specifically, we found that legume-rhizobia interactions at the community level are highly specialised resulting in strongly modular webs, which are not nested, and that invasive legumes do not infiltrate existing native webs but rather form unique and novel modules in webs.

No MeSH data available.


Photographs illustrating semi invaded (a) and univaded (b) sites in close proximity to each other (c) at Helderberg region that were sampled for rhizobia and legumes in this study, showing the presence (white arrow) of acacias that were absent from the nearby univaded site (Photos by JJ Le Roux).
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plw038-F1: Photographs illustrating semi invaded (a) and univaded (b) sites in close proximity to each other (c) at Helderberg region that were sampled for rhizobia and legumes in this study, showing the presence (white arrow) of acacias that were absent from the nearby univaded site (Photos by JJ Le Roux).

Mentions: Our study area, in the Helderberg area of South Africa’s Western Cape Province, represented a gradient of invasion (uninvaded site [never invaded by Australian acacias], semi-invaded site [invasion periphery, 1–10 acacias/m2] and heavily invaded site [invasion core, >10 acacias/m2]; Fig. 1). Heavily invaded sites not only had higher tree densities but also had older trees compared with the semi-invaded area. All sites fell within a 600 m transect. All native legumes were sampled and herbarium samples submitted to the Compton Herbarium (Cape Town, South Africa) for expert identification. Root nodules were also sampled from all native and invasive legume species present at all three sites. At each site ten root nodules from at least five individuals per species were collected, dehydrated and kept on silica gel until needed for bacterial isolations [see Supporting Information].Figure 1.


The structure of legume – rhizobium interaction networks and their response to tree invasions
Photographs illustrating semi invaded (a) and univaded (b) sites in close proximity to each other (c) at Helderberg region that were sampled for rhizobia and legumes in this study, showing the presence (white arrow) of acacias that were absent from the nearby univaded site (Photos by JJ Le Roux).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940501&req=5

plw038-F1: Photographs illustrating semi invaded (a) and univaded (b) sites in close proximity to each other (c) at Helderberg region that were sampled for rhizobia and legumes in this study, showing the presence (white arrow) of acacias that were absent from the nearby univaded site (Photos by JJ Le Roux).
Mentions: Our study area, in the Helderberg area of South Africa’s Western Cape Province, represented a gradient of invasion (uninvaded site [never invaded by Australian acacias], semi-invaded site [invasion periphery, 1–10 acacias/m2] and heavily invaded site [invasion core, >10 acacias/m2]; Fig. 1). Heavily invaded sites not only had higher tree densities but also had older trees compared with the semi-invaded area. All sites fell within a 600 m transect. All native legumes were sampled and herbarium samples submitted to the Compton Herbarium (Cape Town, South Africa) for expert identification. Root nodules were also sampled from all native and invasive legume species present at all three sites. At each site ten root nodules from at least five individuals per species were collected, dehydrated and kept on silica gel until needed for bacterial isolations [see Supporting Information].Figure 1.

View Article: PubMed Central - PubMed

ABSTRACT

We provide data on how legume-rhizobia interaction webs react to invasions by exotic legumes. This is the first study of its kind and found that general hypotheses derived from above-ground mutualistic webs may not hold for below-ground counterparts. Specifically, we found that legume-rhizobia interactions at the community level are highly specialised resulting in strongly modular webs, which are not nested, and that invasive legumes do not infiltrate existing native webs but rather form unique and novel modules in webs.

No MeSH data available.