Oconee Rivers Audubon Society’s “Binoculars for Young Black Birders” Fundraiser Success

During the week of June 1st, EcoReach participated in the inaugural #BlackBirdersWeek on social media, which Kaylee Arnold co-organized. This movement was started by @BlackAFinSTEM on Twitter in response to the video of a white woman who called the police on birdwatcher (or “birder”) Christian Cooper after he requested that she follow regulations and leash her dog in Central Park. As America continues to grapple with systemic racism and violence following the deaths of Ahmaud Arbery, Breonna Taylor, George Floyd, Tony McDade, Nina Pop, and so many others, it has also been highlighted that Black people face unique challenges and discrimination in the field of Ecology or when out in nature, even while doing something as simple as bird watching or going outside for a jog.

Inspired by these events, EcoReach and other OSE members teamed up with Lilly Branch Audubon Society to support the Oconee Rivers Audubon Society’s “Binoculars for Young Black Birders,” a binoculars drive to support young, Black birders in Athens-Clarke County. In just under a few weeks, we raised nearly $20,000 from GoFundMe donations and direct donations to Oconee Rivers Audubon Society (ORAS). With this money, EcoReach is currently working with Clarke County School District (CCSD) to provide individual binoculars and local bird guides to every K-12 Black student in CCSD that would like a pair as well as provide additional binoculars and guides to each CCSD science teacher to use in their classrooms. Lack of access to equipment, such as binoculars, results in substantial inequitable access to outdoor activities and outdoor education. By providing students with their own binoculars and field guides, we can help remove one of the many barriers Black students may face in regards to participating in outdoor activities that so many of us enjoy and take for granted. 

See the campaign here.

Ignoring temperature variation leads to underestimation of the temperature sensitivity of plant litter decomposition

Figure provided by Nate Tomaczyk

The majority of terrestrial net primary production decomposes, fueling detrital food webs and converting dead plant carbon to atmospheric CO 2. There is considerable interest in determining the sensitivity of this process to climate warming. A common approach has been to use spatial gradients in temperature (i.e., latitude or elevation) to estimate temperature sensitivity. However, these studies typically relate decomposition rates to average temperatures at each site along such gradients, ignoring within‐site temperature variation. To evaluate the potential effects of temperature variation on estimates of temperature sensitivity, we simulated plant litter decomposition using both randomly generated and real time series of temperature. This simulation approach illustrated how temperature variation leads to higher decomposition rates at a given mean temperature than is predicted from simulations in which temperature is held constant. Increases in decomposition rate were most evident at cooler sites, where temporal variation in temperature tends to be greater than at warmer sites. This unbalanced effect of temperature variation shifted the slope of the relationships between average temperature and decomposition rate, resulting in lower estimated temperature sensitivities than were used to simulate decomposition. For example, estimates of activation energy (a) were as much as 0.15 eV lower than the true a when decomposition was simulated with the true a set to the canonical respiration value of 0.65 eV . We found that the estimated a was lower than the true a for surface, soil, and air temperatures, but not for stream temperatures, for which there was only a weak relationship between temperature variation and mean temperature. Our results suggest that commonly used methods may underestimate the temperature dependence of litter decomposition, particularly in terrestrial environments. We encourage publication of temperature data that include variation estimates and suggest an alternative method for calculating temperature sensitivity that accounts for variation in temperature.

Tomczyk NJ, Rosemond AD, Bumpers PM, Cummins CS, Wenger SJ, Benstead JP. Ignoring temperature variation leads to underestimation of the temperature sensitivity of plant litter decomposition. Ecosphere. 2020 Feb;11(2):e03050. doi: 10.1002/ecs2.3050.

Emily Bertucci receives Dr. Rebecca Reyburn Sharitz and Carl Byrne Hatfield Fellowship

Picture: Emily Bertucci

Emily Bertucci is the inaugural recipient of the new Dr. Rebecca Reyburn Sharitz and Carl Byrne Hatfield Fellowship. Emily, advised by Dr. Ben Parrott, is researching the proximate mechanisms that produce variation in biological aging – specifically, epigenetic changes that occur with age and how normal age-related changes are impacted by exposures to stressful environments.  This year, she is investigating how exposures to stress during sensitive life stages alters the epigenome and produces variation in aging and life history traits at the individual and population levels.


Incorporating spatial synchrony in the status assessment of a threatened species with multivariate analysis

A painting of the study organism, the Amber Darter (Percina antesella). Artist: Carol Yang.

Spatial synchrony—correlated abundance fluctuations among distinct populations—is associated with increased extinction risk but is not a component of widely-used extinction risk assessments (e.g., IUCN Red List, U.S. Fish and Wildlife Service’s Species Status Assessment). Alongside traditional viability metrics (i.e., the number of populations, their spatial extent, the status of each population), consideration of spatial synchrony in these assessments may provide additional insight into extinction risk as well as the relative importance of intrinsic and extrinsic factors on population dynamics. We demonstrate a method for estimating abundance trends in populations of the endangered freshwater fish, the amber darter (Percina antesella), while simultaneously assessing empirical support for existence of spatial synchrony among its two populations in the Conasauga and Etowah rivers in Georgia, U.S.A. Our analysis was performed using multivariate autoregressive state-space (MARSS) models with annual sampling data from 1996 to 2018 at 16 sites distributed between the two rivers. Our results indicate that amber darter populations have declined substantially, with 9% annual losses in both the Conasauga and Etowah rivers, suggesting rangewide imperilment. Furthermore, model selection indicated little support for models with fully independent dynamics between rivers, which may compound overall extinction risk. This analysis demonstrates the utility of tools such as MARSS models for assessing spatial synchrony and long-term population trajectories of imperiled species, resulting in improved vulnerability assessments that do not assume independence among separate populations.

Stowe, E.S., Wenger, S.J., Freeman, M.C. and Freeman, B.J., 2020. Incorporating spatial synchrony in the status assessment of a threatened species with multivariate analysis. Biological Conservation248, p.108612. doi: 10.1016/j.biocon.2020.108612

Spatial and temporal variation in nest temperatures forecasts sex ratio skews in a crocodilian with environmental sex determination

Picture: Samantha Bock

Check out this news article, “Why baby alligators in some spots could be 98% female by century’s end” in Nature covering the research!

Species displaying temperature-dependent sex determination (TSD) are especially vulnerable to the effects of a rapidly changing global climate due to their profound sensitivity to thermal cues during development. Predicting the consequences of climate change for these species, including skewed offspring sex ratios, depends on understanding how climatic factors interface with features of maternal nesting behaviour to shape the developmental environment. Here, we measure thermal profiles in 86 nests at two geographically distinct sites in the northern and southern regions of the American alligator’s (Alligator mississippiensis) geographical range, and examine the influence of both climatic factors and maternally driven nest characteristics on nest temperature variation. Changes in daily maximum air temperatures drive annual trends in nest temperatures, while variation in individual nest temperatures is also related to local habitat factors and microclimate characteristics. Without any compensatory nesting behaviours, nest temperatures are projected to increase by 1.6–3.7°C by the year 2100, and these changes are predicted to have dramatic consequences for offspring sex ratios. Exact sex ratio outcomes vary widely depending on site and emission scenario as a function of the unique temperature-by-sex reaction norm exhibited by all crocodilians. By revealing the ecological drivers of nest temperature variation in the American alligator, this study provides important insights into the potential consequences of climate change for crocodilian species, many of which are already threatened by extinction.

Bock SL, Lowers RH, Rainwater TR, Stolen E, Drake JM, Wilkinson PM, Weiss S, Back B, Guillette Jr L, Parrott BB. Spatial and temporal variation in nest temperatures forecasts sex ratio skews in a crocodilian with environmental sex determination. Proceedings of the Royal Society B. 2020 May 13;287(1926): 20200210.

A comparison of diversity estimators applied to a database of host–parasite associations

Figure provided by Claire Teitelbaum

Understanding the drivers of biodiversity is important for forecasting changes in the distribution of life on earth. However, most studies of biodiversity are limited by uneven sampling effort, with some regions or taxa better sampled than others. Numerous methods have been developed to account for differences in sampling effort, but most methods were developed for systematic surveys in which all study units are sampled using the same design and assemblages are sampled randomly. Databases compiled from multiple sources, such as from the literature, often violate these assumptions because they are composed of studies that vary widely in their goals and methods. Here, we compared the performance of several popular methods for estimating parasite diversity based on a large and widely used parasite database, the Global Mammal Parasite Database (GMPD). We created artificial datasets of host–parasite interactions based on the structure of the GMPD, then used these datasets to evaluate which methods best control for differential sampling effort. We evaluated the precision and bias of seven methods, including species accumulation and nonparametric diversity estimators, compared to analyzing the raw data without controlling for sampling variation. We find that nonparametric estimators, and particularly the Chao2 and second‐order jackknife estimators, perform better than other methods. However, these estimators still perform poorly relative to systematic sampling, and effect sizes should be interpreted with caution because they tend to be lower than actual effect sizes. Overall, these estimators are more effective in comparative studies than for producing true estimates of diversity. We make recommendations for future sampling strategies and statistical methods that would improve estimates of global parasite diversity.

Also highlighted on UGA’s Center for the Ecology of Infectious Disease website.

Teitelbaum, C.S., Amoroso, C.R., Huang, S., Davies, T.J., Rushmore, J., Drake, J.M., Stephens, P.R., Byers, J.E., Majewska, A.A. and Nunn, C.L. (2020), A comparison of diversity estimators applied to a database of host–parasite associations. Ecography. doi:10.1111/ecog.05143

Graduate Student Symposium 2020 :Jan 31 – Feb 1

The annual Graduate Student Symposium (GSS) will take place January 31 – February 1, 2020. This symposium is organized by OSE graduate students to showcase research happening within the department. It includes an undergraduate poster session, rapid talks, and full-length talks.

Each year features a keynote presentation by an Odum alumni. This year’s keynote speaker is Dr. Rebeca de Jesús Crespo, Phd, ’15, currently an Assistant Professor at Louisiana State University.

Please look at the program for the full schedule of events.

Photos from GSS 2019:


City sicker? A meta‐analysis of wildlife health and urbanization

Photo Credit: Maureen Murray

Urban development can alter resource availability, land use, and community composition, which, in turn, influences wildlife health. Generalizable relationships between wildlife health and urbanization have yet to be quantified and could vary across different measures of health and among species. We present a phylogenetic meta‐analysis of 516 comparisons of the toxicant loads, parasitism, body condition, or stress of urban and non‐urban wildlife populations reported in 106 studies spanning 81 species in 30 countries. We found a small but significant negative relationship between urbanization and wildlife health, driven by considerably higher toxicant loads and greater parasite abundance, greater parasite diversity, and/or greater likelihood of infection by parasites transmitted through close contact. Invertebrates and amphibians were particularly affected, with urban populations having higher toxicant loads and greater physiological stress than their non‐urban counterparts. We also found strong geographic and taxonomic bias in research effort, highlighting future research needs. Our results suggest that some types of health risks are more pronounced for wildlife in urban areas, which could have important implications for conservation.

Murray, M. H., C. A. Sánchez, D. J. Becker, K. A. Byers, K. E. Worsley‐Tonks, and M. E. Craft. 2019. City sicker? A meta-analysis of wildlife health and urbanization. Frontiers in Ecology and the Environment. https://doi.org/10.1002/fee.2126
Read about this article in The Conversation.

Microclimate and larval habitat density predict adult Aedes Albopictus abundance in urban areas

The Asian tiger mosquito, , transmits several arboviruses of public health importance, including chikungunya and dengue. Since its introduction to the United States in 1985, the species has invaded more than 40 states, including temperate areas not previously at risk of -transmitted arboviruses. Mathematical models incorporate climatic variables in predictions of site-specific abundances to identify human populations at risk of disease. However, these models rely on coarse resolutions of environmental data that may not accurately represent the climatic profile experienced by mosquitoes in the field, particularly in climatically heterogeneous urban areas. In this study, we pair field surveys of larval and adult mosquitoes with site-specific microclimate data across a range of land use types to investigate the relationships between microclimate, density of larval habitat, and adult mosquito abundance and determine whether these relationships change across an urban gradient. We find no evidence for a difference in larval habitat density or adult abundance between rural, suburban, and urban land classes. Adult abundance increases with increasing larval habitat density, which itself is dependent on microclimate. Adult abundance is strongly explained by microclimate variables, demonstrating that theoretically derived, laboratory-parameterized relationships in ectotherm physiology apply to the field. Our results support the continued use of temperature-dependent models to predict abundance in urban areas.

Full text: https://doi.org/10.4269/ajtmh.19-0220

Evans, M. V., C. W. Hintz, L. Jones, J. Shiau, N. Solano, J. M. Drake, and C. C. Murdock. 2019. Microclimate and larval habitat density redict adult Aedes albopictus abundance in urban areas. The American Journal of Tropical Medicine and Hygiene.