The O'Brien Lab



Leveraging methods used in ecology to inform microplastics sampling and subsampling

This was a fun collaboration with @HanDefrond & @ChelseaRochman thinking about how best to subsample #microplastics, and using cool statistical metrics to estimate how well samples and subsamples represent particle material types in the environment. I'm excited to see it live!— Anna O'Brien (@anna_mobrien) October 17, 2022 See our results and recommendations out at Chemosphere

Harnessing duckweed-microbiome variation for biotransformation

New! We illustrate harnessing plant-microbiome variation for bioremediation. Microcosms w/ rural duckweed genotypes, diverse microbiomes & algae transformed more model contaminant benzotriazole @EPasseport @LeFevreLab @ME_Frederickson Eric Yu, Clara Pencer— Anna O'Brien (@anna_mobrien) August 29, 2022 See our results and recommendations out at Water Research

Hot off the presses results on methylation in duckweed

Check out my blog for the AGA to see hot off the presses preliminary results on DNA methylation in duckweeds of the Greater Toronto Area, and musings on how it might relate to the surprising salt tolerance of these tiny freshwater plants— Anna O'Brien (@anna_mobrien) February 2, 2022 Over at this American Genetics Association blog post, Anna discusses salt tolerance and methylation in duckweeds.

Insight out at eLife

@LaurichJason and I wrote about work led by @MarcoTodescoCnv on genetic causes and potential drivers of sunflower color variation in the UV range. It is a great read with some sweet figures, I recommend! Our thoughts: the science:— Anna O'Brien (@anna_mobrien) January 21, 2022 Jason Laurich and Anna discussed the surprising results on drivers of hidden UV color variation in sunflowers uncovered by Todesco et. al in eLife.


Microbes have pervasive effects on plant phenology

In a new review, we find microbes living with plants frequently alter plant lifecyle timing, from germination to fruit! Effects vary across microbes, plant stages, & the evolutionary consequences are underexplored. @Botanichole @mrebolleda @maggieRwagner— Anna O'Brien (@anna_mobrien) October 18, 2021 In Microbial effects on plant phenology and fitness we catalogued how microbes affect the timing of plant life history from g...

Contaminants from human activities are ecological stressors

Global change goes beyond temperature as synthetic contaminants increasingly permeate our world, yet ecology and evolution research tends to focus on changing climate alone. An alarming amount of plastic enters the environment as trash, where it fragments into smaller and smaller particles. These particles persist, and have under-explored effects on organisms and their interactions, such as plants and their associated microbes. Some of my recent work ...

Whose trait is it anyways?

We keep finding ways beneficial microbes affect traits of the organisms on which they live. I, @ChandraJack1, @symbiomics & @ME_Frederickson ask the obvious follow-up: how do traits evolve when selection acts on variation in both host and microbe genomes? Our manuscript is out now at ProcB One key insight is that counter-intuitiively, conflict can increase mutualism. When hosts and microbes have fitness peaks at different trait values, this evolutionary conflict can actually cause ho...


Anna quoted in the Christian Science Monitor

Tire wear particles are abundant and ubiquitous, but what are the consequences? and what can we do about it? I am happy to have been a part of this insightful piece in @csmonitor by Lindsey McGinnis @BylineLindsey featuring some truly innovative work by @Tyre_Collective, in addition to a small bit on my favorite tiny plant (duckweed, obviously)  

Paper in Science!

Work led by Rebecca T Batstone shows that microbes evolve to benefit local hosts. One neat aspect of our work is that benefits occurred because loci increasing microbe fitness on local hosts also increased the fitness of local hosts – e.g. microbes were neither “altruistic” nor “cheaters.” Indeed alleles underlying mutual benefits more commonly contributed to evolved microbial differences for host and microbe growth than expected by chance. See article: Experimental evolution makes micro...

Co-authored blog in Drops of Change

A blog post led by U of Toronto grad student Lauren Lawson and co-authored by Anna and other U of T students considers freshwater pollution including road salt and plastics. The post considers both impacts of pollution and ways to move forward - blog here.

Anna's first duckweed papers recently published

Co-occurring winter stressors reduce duckweed survival and growth, as well as benefits from microbiomes, at AJB: Resilience to multiple stressors in an aquatic plant and its microbiome The image above shows one experimental replicate of duckweed responses to salt (NaCl) & benzotriazole (BZT) stressors, with (+) & without (-) their microbiome, for three separate genotypes of duckweed (named MT, KSR, and BH). & Duckweed host a much simpler microbiome, yet ...


Anna's favorite thesis chapter is online

Teosinte phenotypes that differ from low elevation, warm sites (later flowering, larger root mass) to high elevation, cold sites (early flowering, small roots) are shifted by root microbes. More interesting yet, microbes shift the genetic variation and covariation between traits, potentially altering plant responses to selection pressures, e.g. climate change. A favorite thesis chapter is online at Evolution! Microbes may alter plant adaptation to cli...

Duckweed-microbiome interactions shift under stress

Anna’s 2019 Evolution talk on how stress may disrupt locally adapted duckweed-microbe interactions.

News and Views at Molecular Ecology

Hubbard et al 2019 find that root microbes drive a substantial amount of plant defense in Boechera stricta, and that plant and root-microbe pathways to defense are different. I opine here on what separate pathways mean for evolution of plant defense, and what alternate knock-on effects of microbe- and plant- driven defense on insects could mean for tri-trophic interactions.


COCO is out!

Despite decades of research commonly identifying that stressful (cold, infertile) conditions shift interaction outcomes more mutually positive, or at least less antagonistic, the evolutionary implications remain largely overlooked. In Evolutionary Responses to Conditionality in Species Interactions across Environmental Gradients, we predicted the evolutionary consequences of interaction outcomes structured by abiotic gradients using theory and simulations. We posited that as interaction...