Biology subjects

Puzey, J.

Publications and source records attributed to Puzey, J..

5 recordsLinked to original sources

bioRxiv2026

Plant microbiomes have a greater effect than plant size on flowering and growth in Asclepias syriaca

Plants strike a balance between growth and defense. The calculus of how to defend against herbivores, and maximize growth and reproduction, can differ between annuals and perennials. Annuals have a live fast, reproduce young strategy; while perennials may maximize fecundity over years. Milkweed, a herbaceous perennial, is a mix of these two strategies. On one hand, a single individual ramet is functionally a herbaceous annual and vulnerable to herbivory. On the other hand, below ground connections allow ramets to share resources and persist for multiple years, perhaps lowering the cost of localized herbivory. Here, we study the impact of herbivory on the leaf and soil microbiome on milkweed growth and flowering in naturally occurring populations. After controlling for plant size and plant genotype, we asked how the microbiome composition was related to flowering time and growth. We find that the leaf microbiome is a strong predictor of plant growth rate, but not flowering. Conversely, we find that the soil microbiome and plant size predict flowering probability. We found no evidence that herbivory altered the leaf or soil microbiome composition. Together these results provide evidence that plant microbiomes also influence growth and fecundity in natural populations of milkweed. These results also provide evidence that the leaf microbiome in milkweed is stable in the face of herbivory. This study expands our knowledge of the contribution of microbiomes to plant demography in a clonal perennial plant.

ecology↗

bioRxiv2025

The reproductive microbiome inhibits pollen germination in milkweed

We know very little about the reproductive microbiomes of plants. Microbes may play important roles in shaping pollination, fertilization, and seed production - processes which are important evolutionarily, ecologically, and agriculturally. Through a series of field and laboratory experiments, we show that the stigmatic microbiome in milkweeds influences the success of pollination. Isolation of individual bacterial and fungal taxa from stigmatic secretions allowed us to experimentally test their effects on pollen germination. These experiments demonstrate that individual taxa impact pollen differently, with many microbial taxa being neutral, but some being deleterious. Through isolation of microbes from the legs of pollinator insects we found that pollinators are a likely source for pollen-harmful bacterial taxa. Next, by utilizing a natural hybrid zone, we demonstrate species-specific responses to the stigmatic microbiome that be driving asymmetric patterns of gene-flow between species - with Asclepias exaltata being a better pollen host than A. syriaca. This study demonstrates that the reproductive microbiome is an underappreciated player in sexual reproduction of plants. Significance StatementThe results presented here demonstrate an important but previously unappreciated role of stigmatic microbes in plant sexual reproduction. This study demonstrates that the microbial taxa living in stigmatic secretions in milkweed impact pollen germination. We found that filtering out the microbes from stigmatic secretions of milkweed flowers dramatically increases pollen germination. Through isolating microbial taxa from both stigmatic secretions, and pollinator legs, we found that individual microbial taxa impact pollen differently, with many taxa being neutral, but some being deleterious. Finally, by utilizing a naturally occurring milkweed hybrid zone we demonstrated that microbial taxa in stigmatic secretions may be acting as asymmetric prezygotic barrier.

plant biology↗

bioRxiv2025

A high degree of clonal reproduction and aggregated structure of milkweed clones does not affect ramet sexual reproduction

1. Clonal plants have unique population structures where genetic individuals can occupy many locations at once, but the effect of ramet spatial arrangement on demography is poorly understood. 2. We analyzed the spatial, genetic, and demographic characteristics of 798 ramets from four populations of Asclepias syriaca, a highly clonal plant, in northern Virginia. 3. Asclepias syriaca clones varied in size and spatial aggregation: ramets of the same genotype were more likely to be spatially clustered but when clones were small, we observed more spatial dispersion, potentially to avoid competition with self. Despite low genetic variation over all (Genotypes/Number of Individuals = 0.1), ramet sexual reproduction was not related to local genetic variation. Synthesis High rates of clonality in A. syriaca spatially structures demographic and competitive dynamics without impeding sexual reproduction, highlighting how reproductive allocation shapes the population ecology of plants.

ecology↗

bioRxiv2020

Population genetics of transposable element load: a mechanistic account of observed overdispersion

In an empirical analysis of transposable element (TE) abundance within natural populations of Mimulus guttatus and Drosophila melanogaster, we found a surprisingly high variance of TE count (e.g., variance-to-mean ratio on the order of 10 to 300). To obtain insight regarding those evolutionary genetic mechanisms that are may underlie the overdispersed population distributions of TE abundance, we developed a mathematical model of TE population genetics that includes the dynamics of element proliferation and purifying selection on TE load. The modeling approach begins with a master equation for a birth-death process and extends the predictions of the classical theory of TE dynamics in several ways. In particular, moment-based analyses of time-dependent and equilibrium population distributions of TE load reveal that overdispersion is likely to arise via copy-and-paste proliferation dynamics, especially when the elementary processes of proliferation and excision are first-order and approximately balanced. Parameter studies and analytic work confirm this result and further suggest that overdispersed population distributions of TE abundance are unlikely to be a consequence of purifying selection on total element load.

genomics↗

bioRxiv2018

Monarch butterfly and milkweed declines substantially predate the use of genetically modified crops

Monarch butterfly (Danaus plexippus) decline over the past 25 years has received considerable public and scientific attention, in large part because its decline, and that of its milkweed (Asclepias spp.) host plant, have been linked to genetically modified (GM) crops and the associated herbicide use. Therefore, the monarch has emerged as a poster child for the anti-GM movement. Here we use museum and herbaria specimens to extend our knowledge of the dynamics of both monarchs and milkweeds in the United States to more than a century, from 1900-2016. We show that monarch population trends closely follow those of their milkweed hosts; that both monarchs and milkweeds increased during the early 20th century, and that recent declines are actually part of a much longer term decline in both monarchs and milkweed beginning around 1950. Herbicide resistant crops, therefore, are clearly not the only culprit, and likely not even the primary culprit, as these declines began decades before GM crops were introduced.

ecology↗