Archives: Publications

Citation

McKenzie, B. A., A. E. Wilson, and S. Zohdy. 2019. Aedes albopictus is a competent vector of Zika virus: a meta-analysis. PLoS ONE 14(5):e0216794.

Abstract

Background

Much work has been done in recent years to determine the vector competence of Aedes albopictus (Skuse) for Zika virus (ZIKV). If competent, Ae. albopictus could become an important vector in the spread of ZIKV to areas which until now have been considered safe from the virus. Despite much speculation about Ae. albopictus’ competence for ZIKV, there have been, to date, no quantitative syntheses of Ae. albopictus’ competence, nor have the potentially confounding differences between studies been addressed.

Methodology/ principle findings

This study represents a quantitative meta-analysis of the literature surrounding this topic by examining infection rates (IR) and transmission rates (TR) among sample populations of Ae. albopictus at 7 and 14 days post infection (dpi) across 15 journal articles comprising 23 studies. Our analyses examined potentially confounding variables in the studies contained therein, including: geographic origin of viral strain or mosquito population tested, whether sympatry of the tested viral strain and mosquito population was important, and freshness of blood meal. Our results suggest 1) Ae albopictus is a competent vector for ZIKV and 2) that origin of Ae. albopictus population and origin of viral strain had significant effects on the competence of Ae. albopictus to transmit ZIKV.

Conclusions/ significance

These results indicate a need to further explore the effects of methodology on vector competence studies and to examine in more detail the geographic variation in the competence of Ae. albopictus for ZIKV as well as the underlying causes of said variation. The ability of Ae. albopictus to carry and transmit ZIKV also points to a need to create new vector control strategies in case of a ZIKV outbreak in an area where Ae. albopictus is prominent. Finally, this study represents a potential template for future meta-analyses in the field of vector competence, where this type of study has been under-utilized despite the abundance of relevant studies.

Keywords

Link to Publication

Citation

David, K. T., A. E. Wilson, and K. M. Halanych. 2019. Sequencing disparity in the genomic era. Molecular Biology and Evolution 36(8):1624-1627. 

Abstract

Advances in sequencing technology have resulted in the expectation that genomic studies will become more representative of organismal diversity. To test this expectation, we explored species representation of nonhuman eukaryotes in the Sequence Read Archive. Though species richness has been increasing steadily, species evenness is decreasing over time. Moreover, the top 1% most studied organisms increasingly represent a larger proportion of total experiments, demonstrating growing bias in favor of a small minority of species. To better understand molecular processes and patterns, genomic studies should reverse current trends by adopting more comparative approaches.

Keywords

Link to Publication

Citation

Barros, M. U. G., A. E. Wilson, J. I. R. Leitão, S. P. Pereira, R. P. Buley, E. G. Fernandez-Figueroa, and J. Capelo-Neto. 2019. Environmental factors associated with toxic cyanobacterial blooms across 20 drinking water reservoirs in a semi-arid region of Brazil. Harmful Algae 86:128-137.

Abstract

Cyanobacteria are known to produce a wide variety of bioactive, toxic secondary metabolites generally described as hepatotoxins, neurotoxins, cytotoxins, or dermatoxins. In Brazil, the regular monitoring of cyanobacterial toxins has intensified after the death of 65 patients in a hemodialysis clinic in Caruaru in the state of Pernambuco due to microcystin exposure. The primary objective of this study was to use multivariate statistics that incorporated environmental parameters (both biotic and abiotic) to forecast blooms of cyanobacteria and their toxic secondary metabolites in 20 drinking water reservoirs managed by the Water Treatment Company of Ceará (CAGECE) in the semi-arid region of Ceará, Brazil. Across four years (January 2013 to January 2017), 114 different phytoplankton taxa were identified, including 24 cyanobacterial taxa. In general, Ceará reservoirs were dominated by cyanobacteria due to eutrophication but also because of the dry and warm climate found throughout the region. Interestingly, specific cyanobacterial taxa were influenced by different biotic and abiotic factors. For example, nitrogen-to-phosphorus (N:P) and evaporation were positively related to saxitoxin-producing taxa, especially Raphidiopsis raciborskii, while temperature, electrical conductivity, total phosphorus, and transparency (measured as Secchi depth) were positively associated with microcystin-producing taxa, such as Microcystis aeruginosa. Climate forecasts predict higher evaporation and temperatures in the semi-arid Ceará region, which will likely magnify droughts and water scarcity as well as promote toxic cyanobacterial blooms in reservoirs in the future. Therefore, understanding the factors associated with algal blooms dominated by specific taxa is paramount for water resource management.

Keywords

Link to Publication

Citation

Chislock, M. F., O. Sarnelle, L. M. Jernigan, V. R. Anderson, A. Abebe, and A. E. Wilson. 2019. Consumer adaptation mediates top-down regulation across a productivity gradient. Oecologia 190:195-205.

Abstract

Humans have artificially enhanced the productivity of terrestrial and aquatic ecosystems on a global scale by increasing nutrient loading. While the consequences of eutrophication are well known (e.g., harmful algal blooms and toxic cyanobacteria), most studies tend to examine short-term responses relative to the time scales of heritable adaptive change. Thus, the potential role of adaptation by organisms in stabilizing the response of ecological systems to such perturbations is largely unknown. We tested the hypothesis that adaptation by a generalist consumer (Daphnia pulicaria) to toxic prey (cyanobacteria) mediates the response of plankton communities to nutrient enrichment. Overall, the strength of Daphnia’s top–down effect on primary producer biomass increased with productivity. However, these effects were contingent on prey traits (e.g., rare vs. common toxic cyanobacteria) and consumer genotype (i.e., tolerant vs sensitive to toxic cyanobacteria). Tolerant Daphnia strongly suppressed toxic cyanobacteria in nutrient-rich ponds, but sensitive Daphnia did not. In contrast, both tolerant and sensitive Daphnia genotypes had comparable effects on producer biomass when toxic cyanobacteria were absent. Our results demonstrate that organismal adaptation is critical for understanding and predicting ecosystem-level consequences of anthropogenic environmental perturbations.

Keywords

Link to Publication

Citation

Buley, R. P., Z. Yang, M. F. Gladfelter, and A. E. Wilson. 2019. Controlling blue-green algal blooms in aquaculture ponds using hydrogen peroxide. Fish Farming News 2019(1):3-5.

Abstract

Excessive blue-green algae (i.e., cyanobacteria) can harm aquatic organisms, including farmed fish. Although algal populations may be beneficial as they acquire excess nutrients, including potentially toxic forms such as nitrite and ammonia, and produce oxygen through photosynthesis, large algal blooms may lead to anoxia as decaying cells are decomposed by bacteria. In addition, some select strains of blue-green algae may produce chemicals that harm fish health (e.g., microcystins, nodularins) or cause fish filets to taste muddy (i.e., geosmin, 2- methylisoborneol). Both situations can cause significant economic losses to fish farmers around the world.

As our understanding of nuisance algal blooms continues to grow, so too do the means to combat these events. Developed methods can often be placed into the groupings of chemical, biological, and physical controls. Of these, chemical controls have been used to great effect; however, there is concern that some approved algaecides may persist in the environment for extended periods of time and, in certain situations, are too broad-spectrum in their toxicity to be practical. Consequently, alternative chemicals are actively being researched. And, although many algaecides exist, hydrogen peroxide (H2O2) has proved quite effective at reducing blue-green algae (Kay et al. 1982), and is currently an approved FDA

aquaculture drug (FDA 2007). This contribution assesses the utility of H2O2 as an algaecide, its application rate, and other factors which may impede its effectiveness.

Keywords

Dowload Publication (PDF)

Citation

Heine, K. B., A. Abebe, A. E. Wilson, and W. R. Hood. 2019. Copepod respiration increases by 7% per degree °C increase in temperature: a meta-analysis. Limnology and Oceanography Letters (4)3:53-61.

Abstract

Exponential increase in respiration rate with increasing temperature in poikilotherms is well documented, how-ever, the rate of change varies greatly across copepod taxa. Studies often report magnitude of change, but the rate of change in respiration across multiple temperatures is equivocal. We used 32 studies spanning 78 yrs of research and 50 copepod species (three orders) to quantify percent change in respiration rates per one-unit change in temperature. We found that copepod respiration rates increased by approximately 7% perC increase in water temperature across the orders Calanoida, Cyclopoida, and Harpacticoida. Neither food availability norscaling respiration to copepod dry weight affected the rate of change of respiration rates. Studies using Winkler titration to measure oxygen consumption produced significantly larger percent changes in respiration, whereas newer methods such as fiber optics produced smaller effects. These results have far reaching implications for understanding how copepod respiration responds to increasing water temperatures

Keywords

Link to Publication

Citation

Chalkowski, K., A. E. Wilson, C. A. Lepczyk, and S. Zohdy. 2019. Who let the cats out? a global meta-analysis on risk of parasitic infection in indoor versus outdoor domestic cats (Felis catus). Biology Letters 15:20180840. (see the complete Altmetric list; New York Times article; Newsweek article; MSN article)

Abstract

Parasitic infection risks in domestic animals may increase as a result of outdoor activities, often leading to transmission events to and from owners, other domestic animals and wildlife. Furthermore, outdoor access has not been quantified in domestic animals as a risk factor with respect to latitude or parasite transmission pathway. Cats are an ideal model to test parasitic infection risk in outdoor animals because there have been many studies analysing this risk factor in this species; and there is a useful dichotomy in cat ownership between indoor-only cats and those with outdoor access. Thus, we used meta-analysis to determine whether outdoor access is a significant risk factor for parasitic infection in domestic pet cats across 19 different pathogens including many relevant to human, domestic animal and wildlife health, such as Toxoplasma gondii and Toxocara cati. Cats with outdoor access were 2.77 times more likely to be infected with parasites than indoor-only cats. Furthermore, absolute latitude trended towards significance such that each degree increase in absolute latitude increased infection likelihood by 4%. Thus, restricting outdoor access can reduce the risk of parasitic infection in cats and reduce the risk of zoonotic parasite transmission, spillover to sympatric wildlife and negative impacts on feline health.

Keywords

Link to Publication

Citation

Bird, G., C. Kaczvinsky, A. E. Wilson, and N. B. Hardy. 2019. When do herbivorous insects compete? A phylogenetic meta-analysis. Ecology Letters 22:875-883.  (2019 College of Agriculture Outstanding Publication Award)

Abstract

When herbivorous insects interact, they can increase or decrease each other’s fitness. As it stands, we know little of what causes this variation. Classic competition theory predicts that competition will increase with niche overlap and population density. And classic hypotheses of herbivorous insect diversification predict that diet specialists will be superior competitors to generalists. Here, we test these predictions using phylogenetic meta‐analysis. We estimate the effects of diet breadth, population density and proxies of niche overlap: phylogenetic relatedness, physical proximity and feeding‐guild membership. As predicted, we find that competition between herbivorous insects increases with population density as well as phylogenetic and physical proximity. Contrary to predictions, competition tends to be stronger between than within feeding guilds and affects specialists as much as generalists. This is the first statistical evidence that niche overlap increases competition between herbivorous insects. However, niche overlap is not everything; complex feeding guild effects indicate important indirect interactions.

Keywords

Link to Publication

Citation

Chislock, M. F., R. B. Kaul, K. A. Durham, O. Sarnelle, and A. E. Wilson. 2019. Eutrophication mediates rapid clonal evolution in Daphnia pulicaria. Freshwater Biology 64:1275-1283.

Abstract

  1. Laboratory studies have revealed that Daphnia species can evolve to tolerate toxic cyanobacteria in the diet. Specifically, Daphnia from eutrophic lakes where cyanobacteria are common tend to have higher growth rates and survival when fed toxic cyanobacteria than populations from oligotrophic environments with low abundance of cyanobacteria.
  2. We conducted an in‐lake mesocosm (i.e. limnocorral) experiment during the autumn of 2009 to assess the effects of nutrient enrichment on clonal evolution in Daphnia pulicaria. As nutrient enrichment often favours grazing‐resistant cyanobacteria, we hypothesised that fertilisation would influence the genotypic composition of D. pulicaria that vary in tolerance to cyanobacteria. Mesocosms were fertilised to manipulate phytoplankton and cyanobacterial abundance and concentrations of a cyanobacterial toxin (microcystin). Thus, half of the mesocosms were high‐nutrient and half were low‐nutrient. We then stocked half of the mesocosms with a mixture of six genetically‐distinct D. pulicaria genotypes (three genotypes from oligotrophic lakes and three from eutrophic lakes) leaving half of the mesocosms Daphnia‐free to assess grazing effects, using a fully factorial design.
  3. When compared to the low nutrient treatment, high nutrient mesocosms had nearly five‐fold higher chlorophyll a concentrations, eight‐fold higher cyanobacterial dry biomass, and three‐fold higher microcystin levels at the start of the experiment. In contrast, low nutrient mesocosms had phytoplankton concentrations typical of mesotrophic lakes.
  4. Fertilisation strongly affected Daphnia genetic diversity in the mesocosms. Final Daphnia genotype diversity in the mesocosms with low‐cyanobacteria (richness = 5.83, Shannon–Weiner index = 1.55, evenness = 0.88) was similar to the initial stocked diversity (richness = 5.50, Shannon–Weiner index = 1.48, evenness = 0.87). In contrast, final diversity in fertilised mesocosms with high cyanobacteria was greatly reduced (richness = 2, Shannon–Weiner index = 0.17), with one Daphnia genotype that originated from the most‐eutrophic lake being highly dominant (evenness = 0.25). Thus, eutrophication mediated strong clonal selection of a cyanobacteria‐tolerant Daphnia genotype over just 10 weeks.
  5. By the end of the experiment, Daphnia significantly reduced phytoplankton biomass in the high‐nutrient, but not in the low‐nutrient treatment. This difference in effect size was largely driven by the five‐fold higher initial phytoplankton biomass in the high‐nutrient treatment. Thus, the ability of Daphnia to reduce phytoplankton biomass in eutrophic lakes may be driven more so by the abundance of planktivorous fishes, as opposed to the prevalence of cyanobacteria and their associated toxins.

Keywords

Link to Publication

Citation

Wadsworth, P., A. E. Wilson, and W. C. Walton. 2019. A meta-analysis of growth rate in diploid and triploid oysters. Aquaculture 499:9-16.

Abstract

Around 34 years ago, the first reports on the performance of triploid oysters were published. Since then, triploid oysters have offered many benefits to the oyster industry, such as faster growth, improved meat quality, partial sterility, and increased survival due to disease resistance. However, the extent of a triploid growth advantage, in particular, can vary across studies, measurement parameters, environmental conditions and husbandry practices. To quantitatively compare diploid and triploid oyster growth rates, a meta-analysis was performed with 29 published studies using triploid oysters produced by chemical induction or by crossing diploid and tetraploid oysters (i.e., “mated triploids”). The difference in growth rate between ploidy was evaluated using natural log transformed response ratios (ln[3n/2n]) in a random-effects model weighted by sample size. The positive response ratios in 126 of the 148 independent experiments showed a significant growth advantage of the triploid over the diploid. On average, mated triploids grew 20% faster than diploids in shell height and 49% faster in whole wet weight. While chemically induced triploids had marginally less growth advantage than mated triploids, growing on average 8% faster than diploids in shell height and 31% faster in whole wet weight. Response ratios for experiments using mated triploids and measuring whole wet weight was significantly affected by species and length of study, while response ratios for experiments using chemically induced triploids and measuring whole wet weight was significantly affected by initial size at deployment. Conversely, response ratios for experiments using mated triploids or chemically induced triploids and measuring shell height were not affected by any tested moderator. The lack of a triploid growth advantage in 15% of the experiments (22/148) could have been influenced by a variety of factors including intraspecific variation, differences in sampling, husbandry practices, and environmental conditions.

Keywords

Link to Publication