Animals produce a wide array of sounds with highly variable acoustic structures. It is possible to understand the causes and consequences of this variation across taxa with phylogenetic comparative analyses. Acoustic and evolutionary analyses are rapidly increasing in sophistication such that choosing appropriate acoustic and evolutionary approaches is increasingly difficult. However, the correct choice of analysis can have profound effects on output and evolutionary inferences. Here, we identify and address some of the challenges for this growing field by providing a roadmap for quantifying and comparing sound in a phylogenetic context for researchers with a broad range of scientific backgrounds. Sound, as a continuous, multidimensional trait can be particularly challenging to measure because it can be hard to identify variables that can be compared across taxa and it is also no small feat to process and analyse the resulting high‐dimensional acoustic data using approaches that are appropriate for subsequent evolutionary analysis. Additionally, terminological inconsistencies and the role of learning in the development of acoustic traits need to be considered. Phylogenetic comparative analyses also have their own sets of caveats to consider. We provide a set of recommendations for delimiting acoustic signals into discrete, comparable acoustic units. We also present a three‐stage workflow for extracting relevant acoustic data, including options for multivariate analyses and dimensionality reduction that is compatible with phylogenetic comparative analysis. We then summarize available phylogenetic comparative approaches and how they have been used in comparative bioacoustics, and address the limitations of comparative analyses with behavioural data. Lastly, we recommend how to apply these methods to acoustic data across a range of study systems. In this way, we provide an integrated framework to aid in quantitative analysis of cross‐taxa variation in animal sounds for comparative phylogenetic analysis. In addition, we advocate the standardization of acoustic terminology across disciplines and taxa, adoption of automated methods for acoustic feature extraction, and establishment of strong data archival practices for acoustic recordings and data analyses. Combining such practices with our proposed workflow will greatly advance the reproducibility, biological interpretation, and longevity of comparative bioacoustic studies.
Little is known about the marine ecology of anadromous Pacific Lamprey Entosphenus tridentatus and Western River Lamprey Lampetra ayresii. This information is needed to determine how marine life regulates adult abundances and identify management actions that may benefit declining populations. To address this deficit, we compiled historic data, collected lamprey from marine stock assessment surveys and commercial fisheries, and documented fish with Pacific Lamprey wounds. Pacific Lamprey were most commonly caught by midwater trawls targeting Pacific Hake Merluccius productus along the continental shelf break from northern California to northern Washington. Pacific Lamprey ranged in size from 115 mm total length (TL) and 2.9 g to 714 mm TL and 655g (n = 1,912), and were expected to represent multiple ocean ages. The vast majority (93%) of Pacific Lamprey were small (< 300 mm TL), likely in their first year in marine waters. Growth for small Pacific Lamprey was estimated as 0.37 mm/d and 0.13 g/d over the summer. Gut fullness for Pacific Lamprey was high (5.5% of body weight [BW]), but highly variable for larger individuals (range 0‐55% BW). Our results suggest there is a positive relationship between calendar day and lamprey length and condition factor in most years, while the effect of latitude varies by life stage. We documented Pacific Lamprey wounds on 240 individual fish, representing 16 species, of which 6 species are new lamprey hosts. We had comparably few records for Western River Lamprey (n = 72; mean length = 285.5 mm TL), which were primarily found in surface waters on the continental shelf from northern California to southern British Columbia. Our results have implications for both fisheries and conservation management, including development of best practices for lamprey caught by net fisheries, and using new marine information to inform conservation actions.
Grapevine red blotch virus (GRBV) is a DNA virus in the family Geminiviridae. This pathogen is the causal agent of grapevine red blotch disease, which affects cultivated grapevines and leads to negative effects on crop quality and yield. GRBV is present in commercial vineyards across North America, indicating spread may have been largely human mediated. That said, recent surveys have demonstrated that there appears to be secondary transmission, most likely by an insect vector. Here, vineyard insects and plants were surveyed to identify potential candidate vectors and non-crop plants that may act as reservoirs for this pathogen. Results reconfirm that GRBV is limited to Vitis spp., including both cultivated and wild grapevines. Eleven insect genera or species, field collected in vineyards, tested positive for GRBV using quantitative PCR. These insect taxa include unknown Aphididae, the Cicadellids Aceratagallia spp., Acinopterus angulatus, Caladonus coquilleti, Colladonus montanus reductus, Colladonus sp., Empoasca spp., Erythroneura elegantula, and Scaphytopius graneticus, along with the Membracid Spissistilus festinus and an unknown Delphacid. Of these organisms, S. festinus is already known to be capable of transmitting GRBV while Scaphytopius graneticus may merit closer evaluation as a candidate vector.
Trophic interactions are proximate drivers of ecosystem function, including predator-prey dynamics, and their spatio-temporal variability may reflect ecosystem shifts and changes in trophic transfer. We investigated biogeographic structuring of trophic interactions by analyzing multi-decadal time series of diet for Pacific hake Merluccius productus and Chinook salmon Oncorhynchus tshawytscha from a large marine ecosystem. We compared our predictions for spatio-temporal variability of hake and salmon trophoscapes (i.e. spatially explicit predictions of trophic relationships) to inform ecosystem dynamics and fishery bycatch patterns. We have 3 inter-related findings pertaining to the spatial coherence of the trophoscapes and the potential consequences to juvenile and sub-adult (i.e. after the first year at sea but prior to maturation) salmon when sharing foraging areas with Pacific hake. First, the spatial scale of Pacific hake diet represents coastwide variability, and the spatial variability of Chinook salmon diets differs across regions and demonstrates a broad diet. Second, the expectation for increased diet and spatial overlap of Pacific hake and Chinook salmon during low productivity periods (e.g. periods with low krill biomass, suboptimal upwelling) can inform fishery management challenges. In this regard, we explore the role of shared foraging habitats on increased predation, and consequentially reduced recruitment, by Pacific hake on juvenile salmon during sub-optimal upwelling conditions. Third, we show that above-average bycatch of sub-adult Chinook salmon was associated with later spring transition, potentially as a result of both Pacific hake and salmon sharing foraging areas and prey species on the shelf and shelf break.
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