Role of plant relatedness in plant-soil feedback dynamics

What this paper is about

Plants change the soil they grow in, and the changed soil then affects what grows there next. This study grew common milkweed in soil conditioned by several related Asclepias species, across a range of relatedness.

It tests whether closer relatives leave behind soil that is worse for each other, which is one explanation for why related plants do not grow together.

Summarised here from the abstract below. Not the authors’ words.

Abstract

Plants affect associated biotic and abiotic edaphic factors, with reciprocal feedbacks from soil characteristics affecting plants. These two-way interactions between plants and soils are collectively known as plant-soil feedbacks (PSFs). The role of phylogenetic relatedness and evolutionary histories have recently emerged as a potential driver of PSFs, although the strength and direction of feedbacks among sympatric congeners are not well-understood. We examined plant-soil feedback responses of Asclepias syriaca, a common clonal milkweed species, with several sympatric congeners across a gradient of increasing phylogenetic distances (A. tuberosa, A. viridis, A. sullivantii, and A. verticillata, respectively). Plant-soil feedbacks were measured through productivity and colonization by arbuscular mycorrhizal (AM) fungi. Asclepias syriaca produced less biomass in soils conditioned by the most phylogenetically distant species (A. verticillata), relative to conspecific-conditioned soils. Similarly, arbuscular mycorrhizal (AM) fungal colonization of A. syriaca roots was reduced when grown in soils conditioned by A. verticillata, compared with colonization in plants grown in soil conditioned by any of the other three Asclepias species, indicating mycorrhizal associations are a potential mechanism of observed positive PSFs. This display of differences between the most phylogenetically distant, but not close or intermediate, paring(s) suggests a potential phylogenetic threshold, although other exogenous factors cannot be ruled out. Overall, these results highlight the potential role of phylogenetic distance in influencing positive PSFs through mutualists. The role of phylogenetic relatedness and evolutionary histories have recently emerged as a potential driver of plant-soil feedbacks (PSFs), although the strength and direction of feedbacks among sympatric congeners are not well-understood. Congeneric, sympatric milkweeds typically generated positive PSFs in terms of productivity and AM fungal colonization, suggesting the low likelihood of coexistence among tested pairs, with a strength of feedback increasing as the phylogenetic distance increases.

Abstract reproduced from the published paper, which is licensed CC BY. Copyright remains with the authors.

Key terms

phylogenetic relatednessCongenerMutualistsArbuscular Mycorrhizal (Am) FungiAsclepiasPlant–Soil Feedback (Psf)

Milkweeds in this paper

Butterfly Weed Asclepias tuberosa
Common Milkweed Asclepias syriaca
Whorled Milkweed Asclepias verticillata
Prairie Milkweed Asclepias sullivantii
Green Antelopehorn Asclepias viridis

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APA

Milkweed USA. (2026). Role of plant relatedness in plant-soil feedback dynamics of sympatric Asclepias species (listing). Retrieved DATE, from https://milkweedusa.com/research/role-of-plant-relatedness-in-plant-soil-feedback-dynamics-2023/

MLA

"Role of plant relatedness in plant-soil feedback dynamics of sympatric Asclepias species (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/role-of-plant-relatedness-in-plant-soil-feedback-dynamics-2023/. Accessed DATE.

Chicago

Milkweed USA. "Role of plant relatedness in plant-soil feedback dynamics of sympatric Asclepias species (listing)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/research/role-of-plant-relatedness-in-plant-soil-feedback-dynamics-2023/.

BibTeX

@misc{milkweedusa_researchroleofplantrelatedne,
  title  = {Role of plant relatedness in plant-soil feedback dynamics of sympatric Asclepias species (listing)},
  author = {{Milkweed USA}},
  year   = {2026},
  url    = {https://milkweedusa.com/research/role-of-plant-relatedness-in-plant-soil-feedback-dynamics-2023/},
  note   = {Accessed DATE}
}