Biology subjects

Petry, W. K.

Publications and source records attributed to Petry, W. K..

4 recordsLinked to original sources

bioRxiv2026

Demographic trade-offs decouple pollination services from plant population growth

Most plants require animal pollination to reproduce, prompting concern that pollinator declines immediately threaten plant populations. This concern is warranted if pollinator-mediated seed losses cause declines in plant population growth rates ({lambda}). However, demographic trade-offs might reduce the risk of population decline if seed loss improves performance elsewhere in the life cycle. We conducted a multi-year pollination manipulation on four species and measured how demographic vital rates and {lambda} responded. Seed responses did not predict net changes in {lambda}. Reduced pollination decreased seed production, but only caused a net decrease in {lambda} in one species; in the others, improved survival buffered {lambda}. Increased pollination boosted seed production, but at a cost to survival that caused a net reduction in {lambda} in three species. Our results highlight the importance of demographic trade-offs for understanding the impacts of pollinator declines on plant biodiversity and, more broadly, the population-level impacts of changing mutualisms.

ecology↗

bioRxiv2026

Changing pollination rates affect plant life history strategies

An organisms life history strategy is an attempt to optimize fitness, given environmental constraints and inherent demographic tradeoffs. As such, life history helps to shape an organisms ecological and evolutionary responses to environmental change. However, life history can also be shaped by the environment, as the organisms demographic rates respond--directly or through tradeoffs--to the new conditions. This feedback between life history and environment remains poorly understood, limiting our ability to predict the outcomes of environmental change. Here, we studied the effects of environmental change - specifically altered pollination services - on four perennial plant species. We conducted a field-based demography experiment that subjected naturally occurring populations of Delphinium nuttallianum, Hydrophyllum fendleri, Potentilla pulcherrima and Erigeron speciosus to three pollination treatments: ambient (control), reduced, or increased pollination. We estimated population growth rate ({lambda}) and 11 metrics describing life history strategy and demographic resilience from an Integral Projection Model we constructed for each species and parameterized with 4-5 years of census data. Although most life history metrics responded idiosyncratically to pollination treatment, we found consistent effects of pollination on generation time, longevity and, in three of four species, recovery time. Specifically, reduced pollination led to increased longevity, generation time, and recovery time, and increased pollination led to the opposite. These changes in life history resemble shifts along the slow-fast continuum; reduced pollination led to slower lives and increased pollination led to faster lives. This is consequential because generation time and longevity influence short- and long-term population dynamics - for example, by affecting demographic stochasticity and sensitivity to environmental stochasticity, or rates of adaptation to novel conditions. Notably, these changes occurred largely independent from changes in population growth. Altogether, our results highlight changes in life history as an important but underappreciated consequence of environmental change.

ecology↗

bioRxiv2025

Spring ephemeral Erythronium umbilicatum may not be vulnerable to phenological mismatch with overstory trees

PremiseThe defining life history strategy of spring ephemeral wildflowers is their avoidance of shading by trees during the brief, high-light period before canopy leaf-out. Studies suggest that spring ephemerals will experience increased light competition because canopy leaf-out is more sensitive to warming than is the phenology of spring ephemerals. However, it remains unclear how longer durations of shade will alter the population dynamics of spring ephemerals and whether all populations are at risk. MethodsWe experimentally shaded Erythronium umbilicatum for one to six additional weeks prior to canopy leaf-out to test for immediate and lagged effects of early shading on the timing of senescence and the probability of survival and flowering. To predict the potential for earlier shading, we combined long-term time series of spring air temperature, remotely-sensed tree leaf-out, and E. umbilicatum flowering phenology in North Carolina, USA. Key resultsEarly shading did not alter E. umbilicatum until the following year, when more-shaded plants senesced later. We found no change in year-to-year survival, and a reduction in the probability of flowering only when plants experienced extremely early shading. Moreover, E. umbilicatum phenology was more sensitive than tree leaf-out to warming temperatures. Under climate warming, we project that E. umbilicatum is unlikely to experience shortened periods of high light. ConclusionsOur findings show that a plant species defining life history strategy does not necessarily predict their sensitivity to phenological mismatches. This complicates, but also underscores the importance of identifying the most vulnerable species and directing our research efforts accordingly.

ecology↗

bioRxiv2021

Rcompadre and Rage - two R packages to facilitate the use of the COMPADRE and COMADRE databases and calculation of life history traits from matrix population models

O_LIMatrix population models (MPMs) are an important tool for biologists seeking to understand the causes and consequences of variation in vital rates (e.g., survival, reproduction) across life cycles. Empirical MPMs describe the age- or stage-structured demography of organisms and usually represent the life history of a population during a particular time frame at a specific geographic location. C_LIO_LIThe COMPADRE Plant Matrix Database and COMADRE Animal Matrix Database are the most extensive resources for MPM data, collectively containing >12,000 individual projection matrices for >1,100 species globally. Although these databases represent an unparalleled resource for researchers, land managers, and educators, the current computational tools available to answer questions with MPMs impose significant barriers to potential COM(P)ADRE database users by requiring advanced knowledge to handle diverse data structures and program custom analysis functions. C_LIO_LITo close this knowledge gap, we present two interrelated R packages designed to (i) facilitate the use of these databases by providing functions to acquire, quality control, and manage both the MPM data contained in COMPADRE and COMADRE, and a users own MPM data (Rcompadre), and (ii) present a range of functions to calculate life history traits from MPMs in support of ecological and evolutionary analyses (Rage). We provide examples to illustrate the use of both. C_LIO_LIRcompadre and Rage will facilitate demographic analyses using MPM data and contribute to the improved replicability of studies using these data. We hope that this new functionality will allow researchers, land managers, and educators to unlock the potential behind the thousands of MPMs and ancillary metadata stored in the COMPADRE and COMADRE matrix databases, and in their own MPM data. C_LI

ecology↗