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Publications by EEOB faculty June 1 - June 30

June 25, 2018

Publications by EEOB faculty June 1 - June 30

eeob 2016
The role of gut microbiota in the regulation of standard metabolic rate in female Periplaneta americana
Paul A. Ayayee, Andrew Ondrejech, George Keeney and Agusti Munoz-Garcia. 2018. PeerJ 6:e4717; DOI 10.7717/peerj.4717

Abstract

Insect gut microbiota contribute significantly to host nutritional ecology. Disrupting insect gut microbial assemblages impacts nutrient provisioning functions, and can potentially affect host standard metabolic rate (SMR), a measure of host energy balance. In this study, we evaluated the effect of disrupting gut microbial assemblages on the SMR of female Periplaneta americana cockroaches fed dog food (DF, high protein/carbohydrate (p/c) ratio), and cellulose-amended dog food (CADF, 30% dog food, 70% cellulose, low p/c ratio) diets, supplemented with none, low, or high antibiotic doses. Bacterial loads decreased significantly between diet types (P = 0.04) and across antibiotic doses (P = 0.04). There was a significant diet type x antibiotic dose interaction on SMR of females on both diets (P = 0.05) by the end of the seven-day experimental period. In CADF-fed females, SMR decreased linearly with decreasing bacterial load. However, SMR of DF-fed females on the low dose was significantly higher than those in the control and high dose groups. This is interpreted as a diet-dependent response by low dose DF-fed females to the loss of nutritional services provided by gut bacteria. Severe reductions in bacterial load at high doses reduced SMR of females on both diet types. This study provides insights into the potential role of gut bacteria as modulators of host energy expenditure under varying dietary conditions.

Mycosporine-like amino acids (MAAs)—producing Microcystis in Lake Erie: Development of a qPCR assay and insight into its ecology

Chenlin Hu, Stuart A. Ludsin, Jay F. Martin, Elke Dittmann, Jiyoung Lee. 2018. Harmful Algae 77:1-10. https://doi.org/10.1016/j.hal.2018.05.010

Abstract

Mycosporine-like amino acids (MAAs) are UV-absorbing metabolites found in cyanobacteria. While their protective role from UV in Microcystis has been studied in a laboratory setting, a full understanding of the ecology of MAA-producing versus non-MAA-producing Microcystis in natural environments is lacking. This study presents a new tool for quantifying MAA-producing Microcystis and applies it to obtain insight into the dynamics of MAA-producing and non-MAA-producing Microcystis in Lake Erie. This study first developed a sensitive, specific TaqMan real-time PCR assay that targets MAA synthetase gene C (mysC) of Microcystis (quantitative range: 1.7 × 101 to 1.7 × 107 copies/assay). Using this assay, Microcystis was quantified with a MAA-producing genotype (mysC+) in water samples (n = 96) collected during March-November 2013 from 21 Lake Erie sites (undetectable − 8.4 × 106 copies/ml). The mysC+ genotype comprised 0.3–37.8% of the Microcystis population in Lake Erie during the study period. The proportion of the mysC+ genotype during high solar UV irradiation periods (mean = 18.8%) was significantly higher than that during lower UV periods (mean = 9.7%). Among the MAAs, shinorine (major) and porphyra (minor) were detected with HPLC-PDA-MS/MS from the Microcystis isolates and water samples. However, no significant difference in the MAA concentrations existed between higher and lower solar UV periods when the MAA concentrations were normalized with Microcystis mysC abundance. Collectively, this study’s findings suggest that the MAA-producing Microcystis are present in Lake Erie, and they may be ecologically advantageous under high UV conditions, but not to the point that they exclusively predominate over the non-MAA-producers.

Ontogeny of Megalolaelaps colossus sp. nov. (Acari: Megalolaelapidae), an enigmatic symbiont of dung beetles (Coleoptera: Scarabaeidae) in Colombia

Orlando Cómbita-Heredia, Edwin Javier Quintero-Gutiérrez & Hans Klompen. 2018. Systematic and Applied Acarology 23(6):1102-1124. https://doi.org/10.11158/saa.23.6.7

Abstract

Post-embryonic development of Megalolaelaps colossus sp. nov., is described and illustrated. This unusually large species of mite is closely associated with the dung beetle Oxysternon conspicillatum (Weber) (Coleoptera: Scarabaeidae) in Colombia. All instars of the mite occur on the beetle, except for the larva. This is the first description of all instars for a species in this genus. 

Testing for the presence of cryptic diversity in tail-dropper slugs (Prophysaon) using molecular data

Megan L Smith,  Megan Ruffley, Andrew M Rankin, Anahí Espíndola  David C Tank  Jack Sullivan Bryan C Carstens. 2018. Biological Journal of the Linnean Society, 124 (3): 518–532. https://doi.org/10.1093/biolinnean/bly067

Abstract

The Pacific Northwest of North America contains two disjunct temperate rainforests, one in the Coastal and Cascades Ranges and another in the Northern Rocky Mountains. These rainforests harbour > 200 disjunct and endemic taxa, with coastal and inland populations separated by the Columbia Basin. For several taxa, molecular data have revealed cryptic diversity structured across the Columbia Basin. Here, we use information from previously studied taxa and a machine-learning framework to predict that tail-dropper slugs in the genus Prophysaon (Prophysaon andersoni, Prophysaon coeruleum, Prophysaon dubium and the Prophysaon vanattae/Prophysaon humile complex) should lack cryptic diversity. This prediction is supported by results from species distribution models (SDMs), which suggest that all taxa lacked suitable habitat in the inland rainforests during the Last Glacial Maximum. We collected COI data and tested these predictions using approximate Bayesian computation and found that models of recent dispersal between inland and coastal populations received strong support. Finally, we used posterior predictive simulations to show that the best model was a reasonable fit to the data for all taxa. Our study highlights the utility of predictive modelling in a comparative phylogeographical framework and illustrates how posterior assessments of model fit can improve confidence in model-based phylogeographical analysis.
 

Evidence that Myotis lucifugus ‘subspecies’ are five non-sister species, despite gene flow

Ariadna E. Morales, Bryan C. Carstens. 2018. Systematic Biology. view paper here.

Abstract

While genetic exchange between non-sister species was traditionally considered to be rare in mammals, analyses of molecular data in multiple systems suggest that it may be common. Interspecific gene flow, if present, is problematic for phylogenetic inference, particularly for analyses near the species level. Here, we explore how to detect and account for gene flow during phylogeny estimation using data from a clade of North American Myotis bats where previous results have led researchers to suspect that gene flow among lineages is present. Initial estimates of phylogenetic networks and species trees indicate that subspecies described within M. lucifugus are paraphyletic. In order to explore the extent to which gene flow is likely to interfere with phylogeny estimation, we use posterior predictive simulation and a novel ABC approach based on gene tree distances. The former indicates that the species tree model is a poor fit to the data, and the latter provides evidence that a species tree with gene flow is a better fit. Taken together, we present evidence that the currently recognized M. lucifugus subspecies are paraphyletic, exchange alleles with other Myotis species in regions of secondary contact, and should be considered independent evolutionary lineages despite their morphological similarity.