Biology subjects

Wright, M. T. G.

Publications and source records attributed to Wright, M. T. G..

4 recordsLinked to original sources

bioRxiv2022

Multi-marker DNA metabarcoding detects suites of environmental gradients from an urban harbour

There is increasing need for biodiversity monitoring, especially in places where potential anthropogenic disturbance may significantly impact ecosystem health. We employed a combination of traditional morphological and bulk macroinvertebrate metabarcoding analyses to benthic samples collected from Toronto Harbour (Ontario, Canada) to compare taxonomic and functional diversity of macroinvertebrates and their responses to environmental gradients. At the species rank, sites assessed using COI metabarcoding showed more variation than sites assessed using morphological methods. Depending on the assessment method, we detected gradients in magnesium (morphological taxa), ammonia (morphological taxa, COI sequence variants), pH (18S sequence variants) as well as gradients in contaminants such as metals (COI & 18S sequence variants) and organochlorines (COI sequence variants). Observed responses to contaminants such as aromatic hydrocarbons and metals align with known patchy distributions in harbour sediments. We determined that the morphological approach may limit the detection of macroinvertebrate responses to lake environmental conditions due to the effort needed to obtain fine level taxonomic assignments necessary to investigate responses. DNA metabarcoding, however, need not be limited to macroinvertebrates, can be automated, and taxonomic assignments are associated with a certain level of accuracy from sequence variants to named taxonomic groups. The capacity to detect change using a scalable approach such as metabarcoding is critical for addressing challenges associated with biodiversity monitoring and ecological investigations.

genomics↗

bioRxiv2020

Deconstructing biodiversity-ecosystem function relationships: Filtering of macroinvertebrate traits in a large river floodplain

The Biodiversity-Ecosystem Function hypothesis postulates that higher biodiversity is correlated with ecosystem function by providing a high number of filled niches through species response types and resource use patterns. Through their high spatio-temporal habitat diversity, floodplains are highly productive ecosystems, supporting communities that are naturally resilient and highly diverse. We examined linkages among floodplain wetland habitats, invertebrate communities and their associated traits, and ecosystem function across 60 sites within the floodplain wetlands of the lower Wolastoq | Saint John River, New Brunswick, using structural equation modelling and Threshold Indicator Taxa ANalysis (TITAN2). We identified key environmental filters of invertebrate communities, namely linking increased niche differentiation through historical change, flood pulse dynamics, and macrophyte bed complexity with increased taxa and functional diversity. Examination of traits linked to ecosystem functions revealed that healthy wetlands with higher primary productivity were associated with greater functional evenness and richness, while habitat patches with increased decomposition rates had low functional richness, reflecting highly disturbed habitat. Our results highlight key differences between wetland and riverine ecosystems, relating to how critical functions support healthy wetland habitats by providing increased resilience to disturbance, here associated with differing levels of conservation protection.

ecology↗

bioRxiv2020

Propylene glycol-based antifreeze as an effective preservative for DNA metabarcoding of benthic arthropods

Maintaining the integrity of DNA in bulk environmental samples from source to laboratory is crucial for capturing the true range of taxa present within an ecosystem. Preservation consideration of DNA is particularly important if samples are being collected in remote areas and by non-specialist citizen scientists in nationwide programs. Traditionally, absolute ethanol is used as the preferred preservative for environmental samples collected for downstream DNA metabarcoding analyses. However, transport, shipping and DNA extraction of samples preserved in ethanol is a lengthy procedure due to safety restrictions and the requirement of full ethanol evaporation prior to extraction. We examined the efficacy of an easily accessible, non-toxic propylene glycol-based antifreeze as an alternative to absolute ethanol for preserving macroinvertebrate DNA from bulk-benthos DNA samples. We tested the differences in both cytochrome oxidase I (COI) exact sequence variants (ESVs) and COI taxonomic orders detected in both ethanol and antifreeze samples using two processing methods (no evaporation of preservative versus full evaporation). In addition, we assessed the detection of families and genera within the Arthropoda phylum for preservative type, site and processing method. Our results suggest that antifreeze is a suitable alternative to ethanol, a greater global ESV richness reported for antifreeze samples. Additionally, a higher proportion of arthropod reads in ESVs were detected in antifreeze (average 69%) compared with ethanol (average 53%). Finally, antifreeze samples produced similar results for the different processing methods, whereas ethanol samples failed to produce similar results without prior evaporation. Although ethanol is currently widely used for DNA preservation, our results demonstrate that by using antifreeze, it is possible to achieve similar taxonomic coverage and community assemblages of bulk-benthos DNA samples for macroinvertebrates, with the added simplicity and shorter laboratory processing time achieved using an easily available, unregulated preservative.

genomics↗

bioRxiv2019

Metabarcoding a Metacommunity: detecting change in a wetland wilderness

The complexity and natural variability of ecosystems present a challenge for reliable detection of change due to anthropogenic influences. This issue is exacerbated by necessary trade-offs that reduce the quality and resolution of survey data for assessments at large-scales. The Peace-Athabasca Delta (PAD) is a large inland wetland complex in northern Alberta, Canada. Despite its geographic isolation, the PAD is threatened by encroachment of oil sands mining in the Athabasca watershed, and hydroelectric dams in the Peace watershed. Methods capable of reliably detecting changes in ecosystem health are needed to evaluate and manage risks. Between 2011 and 2016, aquatic macroinvertebrates were sampled across a gradient of wetland flood frequency, applying both microscope-based morphological identification, and DNA metabarcoding. Using multi-species occupancy models, we demonstrate that DNA metabarcoding detected a much broader range of taxa and more taxa per sample compared to traditional morphological identification, and was essential to identifying significant responses to flood and thermal regimes. We show that family-level occupancy masks high variation among genera, and for the first time, quantify the bias of barcoding primers on the probability of detection in a natural community. Interestingly, patterns of community assembly were near random, suggesting a strong role of stochasticity in the dynamics of the metacommunity. This variability seriously compromises effective monitoring at local scales, but also reflects resilience to hydrological and thermal variability. Nevertheless, simulations showed the greater efficiency of metabarcoding, particularly at a finer taxonomic resolution, provided the statistical power needed to detect change at the landscape scale.

ecology↗