SFS Annual Meeting

6/03/2024  |   10:30 - 10:45   |  Freedom Ballroom E

NONLINEAR THINKING IN ECOLOGY AND EVOLUTION: THE CASE FOR STOICHIOMETRIC CONTROL POINTS Nonlinear dynamics govern many ecological processes, and understanding thresholds is important to measuring and forecasting effects of climate change and management of natural resources. However, it remains challenging to identify how and if such thresholds scale across biological levels of organization. Ecological stoichiometry, the study of the balance of multiple elements and energy in ecological systems, provides a framework for such an endeavor. In this study, we combine ecological stoichiometry with the concept of “control points” to reveal and study the ways in which nonlinear dynamics operate in evolutionary and ecological processes across organism, population, community, and ecosystem scales. We define these thresholds as “stoichiometric control points” (hereafter SCP): the elemental ratio at which an organism, population, clade, community, or ecosystem exhibits a nonlinear change in an ecological or evolutionary state or process. Here, we examine and show how SCPs can be described across different scales of biological and evolutionary organization. We included a mix of simulation modeling, literature analysis, and empirical examples from diverse systems and ecological scales including: cyanotoxin production in eutrophic lakes, alder-salmon dynamics, and the Cambrian Explosion. Collectively, we demonstrate that SCPs are widespread and consequential across levels of biological organization. Thus, formalization of the SCP concept holds promise for advancing our understanding of nonlinear dynamics through the lens of ecological stoichiometry. We provide recommendations for innovative approaches to encourage further applications of SCPs to ecological theory.

Benjamin Tumolo (Primary Presenter/Author), University of Wyoming, bbtumolo@gmail.com;

Carly Olson (Co-Presenter/Co-Author), University of Nebraska-Lincoln, colson41@unl.edu;

Erin Larson (Co-Presenter/Co-Author), University of Alaska-Anchorage, ern.larson@gmail.com;

Halvor Halvorson (Co-Presenter/Co-Author), University of Central Arkansas, hhalvorson@uca.edu;

Cathrine Wagner (Co-Presenter/Co-Author), University Of Wyoming, btumolo@uwyo.edu;

Felicia Osburn (Co-Presenter/Co-Author), Baylor University, felicia_osburn1@baylor.edu;

Eric Moody (Co-Presenter/Co-Author), Middlebury College, erickmoody@gmail.com;

Linnea Rock (Co-Presenter/Co-Author), University Of Wyoming, lrock1@uwyo.edu;

Uchechukwu Ogbenna (Co-Presenter/Co-Author), University of Nebraska-Lincoln, uogbenna2@huskers.unl.edu;

Eli Wess (Co-Presenter/Co-Author), University of Central Arkansas, ewess@cub.uca.edu;

Briante Najev (Co-Presenter/Co-Author), University of Iowa, briantenajev@uiowa.edu ;

Anthony Pignatelli (Co-Presenter/Co-Author), University of South Carolina, PIGNATEA@email.sc.edu;

Jessica Corman (Co-Presenter/Co-Author), University of Nebraska-Lincoln, jcorman3@unl.edu;

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6/03/2024  |   10:45 - 11:00   |  Freedom Ballroom E

To live is to eat and excrete: How Trinidadian guppies mediate nutrient recycling Consumers can act as sources or sinks of limiting nutrients and thus play an essential role in ecosystem nutrient dynamics. They vary in how they eat, assimilate, and excrete nutrients, leading to differences in their body stoichiometry. Local environmental conditions can influence consumer stoichiometry, and at the same time, stoichiometry can affect environmental nutrient levels. Trinidadian guppies (Poecilia reticulata) raised in high versus low-predation sites have been shown to influence their local ecosystem dynamics through divergent levels of nutrient excretion. Despite these observations, whether this difference in their stoichiometry has a genetic basis and thus has long-term consequences for eco-evolutionary dynamics remains unexplored. To determine the role of genetic and environmental factors on stoichiometric traits, I reared third-generation (F3) common-garden Trinidadian guppies from high and low-predation populations under high versus low-quality diets. Specifically, I reared both groups under diets with varying elemental compositions and measured tissue stoichiometry and excretion rates upon maturity. Results show that high-predation F3 guppies have higher ammonium excretion rates than low-predation F3 guppies. This nicely aligns with findings in the wild, suggesting that excretion rates have a genetic basis and can rapidly evolve. These results have important implications for the eco-evolutionary dynamics of consumer-driven recycling.

Amina Mohamed (Primary Presenter/Author), Cornell University, am2565@cornell.edu;

Nimisha Gautam (Co-Presenter/Co-Author), Cornell University, ng394@cornell.edu;

Jeferson Ribeiro Amaral (Co-Presenter/Co-Author), Cornell University, jr982@cornell.edu;

Tyler D Gerencser (Co-Presenter/Co-Author), Cornell University, tdg45@cornell.edu;

Swanne P Gordon (Co-Presenter/Co-Author), Cornell University, swannegordon@cornell.edu;

Andrés López-Sepulcre (Co-Presenter/Co-Author), Cornell University, lopezsepulcre@gmail.com;

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6/03/2024  |   11:00 - 11:15   |  Freedom Ballroom E

Linking Host-Virus Dynamics to Ecosystem Level Processes: Viral Infection of Sulfolobus islandicus (S17 and S42) Viruses are recognized as major ecological and biogeochemical drivers in aquatic systems. They depress autotrophic production and cycle autotrophic nitrogen/phosphorus back into dissolved pools through the formation of the host+virus system. We devised and validated a conceptual framework that establishes a connection between the growth patterns and elemental composition of both the host and virus, elucidating their interplay and its impact on infective outcomes with potential implications at the ecosystem level. Two strains of Sulfolobus islandicus (S17 and S42) were uninfected or infected with Sulfolobus spindle-shaped virus SSV8 with a starting MOI of 0.5. Host and virus growth were measured across early lag, early exponential, late exponential, carrying capacity, and death phases. Particulate and dissolved phases were separated and analyzed for carbon, nitrogen, and phosphorus or dissolved organic and inorganic nitrogen and phosphorus, respectively. We hypothesize hosts more elementally like their respective virus will be more susceptible to viral infection leading to an overall higher viral titer and greater depression in host growth. We also investigated the influence of host elemental composition and infection status throughout growth stages, exploring the implications for both the abiotic and biotic environment. Our results suggest that, hosts more elementally like their virus, increase viral proliferation and strain and/or infection status create elementally distinct signatures in the particulate and dissolved pools potentially having consequences for fluxes within the detrital or dissolved nutrient pools. Expanding our proposed framework to additional host+virus systems may allow for effective estimations of virulence and link this to ecosystem level processes.

Samuel Dias (Primary Presenter/Author), University of Arkansas, sadias@uark.edu;

Yeasin Ahmed (Co-Presenter/Co-Author), University of Arkansas, yahmed@uark.edu;

Clay Prater (Co-Presenter/Co-Author), University of Arkansas, prater.clay@gmail.com;

Ruben Ceballos (Co-Presenter/Co-Author), University of California, Merced, rceballos@ucmerced.edu ;

Michelle Evans-White (Co-Presenter/Co-Author), University of Arkansas, mevanswh@uark.edu;

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6/03/2024  |   11:15 - 11:30   |  Freedom Ballroom E

PLOIDY LEVEL, BUT NOT DEGREE OF PHOSPHORUS LIMITATION, ALTERED GROWTH RATE OF A FRESHWATER SNAIL What drives and maintains the large variation of ploidy levels and genome size within the eukaryotic kingdom is a long-standing question in biology. At the organismal level, polyploidization is caused by one or more whole-genome duplications and can result in individuals having three or more complete chromosome sets. Organisms with relatively large genomes, including polyploids, require more phosphorus (P) to grow and reproduce. Consequently, we predicted that life-history traits of higher-ploidy level individuals will be more severely affected by P limitation than lower-ploidy individuals. We manipulated diets of diploid, triploid, and tetraploid Potamopyrgus antipodarum, a freshwater snail, with “moderately P limiting” and “severely P limiting” algae and measured the individual growth rate of multiple individuals. We found that growth rates were highest in triploids and tetraploids ((p < 0.001). Diploids grew at one third the rate of triploids (p < 0.001) and tetraploids (p = 0.006). Diet treatments had no effect on growth rate (p = 0.223). We found no evidence that the effect of diet treatment differed by ploidy level (p = 0.984). From these results we infer that ploidy level has the strongest effect on growth rate in P. antipodarum. Other research investigating differences in growth rate across ploidy levels in P. antipodarum found similar results to ours. In contrast to similar studies, we found no evidence that P limitation affects growth rate, perhaps because neither of our diets provided sufficient P for growth, suggesting that P limitation, regardless of the magnitude, has similar effects on growth rate.

Briante Lewis Najev (Primary Presenter/Author), University of Iowa, briante-najev@uiowa.edu;

Amy Krist (Co-Presenter/Co-Author), University of Wyoming, krist@uwyo.edu;

Maurine Neiman (Co-Presenter/Co-Author), University of Iowa, maurine-neiman@uiowa.edu;

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6/03/2024  |   11:30 - 11:45   |  Freedom Ballroom E

SEASONAL CHANGES IN PHYTOPLANKTON COMMUNITY STRUCTURE AND STOICHIOMETRY OF URBAN PONDS IN CENTRAL ARKANSAS In Arkansas, USA, ponds cover over 63,000 hectares yet have been largely overlooked in comparison to other aquatic systems. This knowledge gap is particularly noticeable concerning urban ponds. Given the increasing occurrences of harmful algal blooms in freshwater systems due to eutrophication and rising temperatures, understanding the nutrient dynamics and phytoplankton communities in urban ponds is crucial for safeguarding aquatic life and public health. Our study focused on investigating how urbanization affects seasonal nutrient dynamics and phytoplankton communities in 25 ponds, which ranged from 0-99% total developed land cover in the watershed. From May 2022 - April 2023, we sampled seasonally for total and dissolved nitrogen (N) and phosphorus (P), particulate carbon and N, and phytoplankton enumeration. Water quality parameters such as temperature (C), pH, and dissolved oxygen (% and mg L-1) were recorded during sampling. Our preliminary results indicate that ~75% of ponds experienced an increase in total N:total P between Summer and Fall which overall was driven by an increase in TN and a decrease in TP in most ponds. Furthermore, we observed a positive correlation between cyanobacteria biovolume (as a % of total biovolume) and increasing total developed land cover. While significant seasonal differences in dissolved inorganic N (DIN): soluble reactive P (SRP) were identified, no significant relationship was found between DIN:SRP and total developed land cover. This shift in nutrient ratios is anticipated to influence the seasonal variation in phytoplankton communities, responding not only to changing nutrient availability but also to environmental factors such as temperature.

Felicia Osburn (Primary Presenter/Author), University of Central Arkansas, fosburn@uca.edu;

Aidan Patton (Co-Presenter/Co-Author), University of Central Arkansas, apatton5@cub.uca.edu;

William Armstrong (Co-Presenter/Co-Author), University of Central Arkansas, warmstrong@cub.uca.edu;

Nicole Wagner (Co-Presenter/Co-Author), Oakland University, nicolewagner@oakland.edu;

Halvor Halvorson (Co-Presenter/Co-Author), University of Central Arkansas, hhalvorson@uca.edu;

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6/03/2024  |   11:45 - 12:00   |  Freedom Ballroom E

ASSESSING ALGAL RESPONSE METRICS IN FOREST STREAMS: HOW MUCH, WHEN, AND IN WHAT WAY DO BENTHIC ALGAE RESPOND TO NITROGEN AND PHOSPHORUS ENRICHMENT? The 2018-19 National Rivers and Streams Assessment identified nitrogen (N) and phosphorus (P) pollution as the leading stressor to U.S. stream and river integrity. Although nutrient pollution predictably affects algal biomass in larger, open-canopy streams subject to high light, small forest streams collectively drain large areas of land and are also vulnerable to enrichment. We tested effects of long-term (2-year) experimental N and P additions on algal biomass (chlorophyll a and ash-free dry mass [AFDM]) and stoichiometry (algal nutrient:carbon ratios) in five headwater forest streams. Streams were enriched to achieve N:P molar ratios ranging from 2:1 to 128:1 (concentrations elevated to 90-11 ug/L P and 80-650 ug/L N, respectively). Average monthly responses were compared to one year of pretreatment data and separated into high- and low-light months. The greatest response to enrichment was in chlorophyll a, which was positively related to N and increased on average ~9.3× across both years and up to ~20.3× during open-canopy periods. AFDM increased only slightly. Mean algal P:carbon (P:C) ratios increased 2.1× and N:C ratios 1.4× over the two years of enrichment. Algal P:C, which increased with streamwater P, was the only response metric that varied along the streamwater N:P gradient. Our results highlight that even heavily shaded streams can show relatively large responses to low-level N and P enrichment and effects are greatest during high-light months. Variables differed in response to N and P gradients, with chlorophyll a responding to N and algal P content responding to streamwater N:P.

Amy D. Rosemond (Primary Presenter/Author), University of Georgia, rosemond@uga.edu;

Phillip Bumpers (Co-Presenter/Co-Author), University of Georgia, bumpersp@gmail.com;

John Kominoski (Co-Presenter/Co-Author), Florida International University, jkominos@fiu.edu;

Jonathan P. Benstead (Co-Presenter/Co-Author), The University of Alabama, jbenstead@ua.edu;

Vlad Gulis (Co-Presenter/Co-Author), Coastal Carolina University, vgulis@coastal.edu;

John C. Maerz (Co-Presenter/Co-Author), University of Georgia, jcmaerz@uga.edu;

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