ABSTRACT The Bolinao-Anda Reef Complex (BARC) in northwestern Philippines is one of the most heavily impacted reef systems in the Philippines, experiencing recurring marine heat waves and declining water quality due to coastal development and mariculture. As ocean warming and declining water quality continue, stress-tolerant coral species are expected to become increasingly dominant. Understanding how these corals respond to elevated temperatures in the early stages is critical for predicting future reef trajectories. In this study, we examined survival and development of embryos, settlement and survival of larvae, and survival of recruits of the stress-tolerant corals Favites abdita and Favites colemani collected from BARC under control (28°C) and elevated (33-35°C) temperatures. In both species, elevated temperature did not significantly affect embryo survival and development, larval survival and settlement, or recruit survival. Results show that early stages of Favites development can tolerate temperatures ranging from 28 to 35°C. These findings support the classification of Favites spp. as stress-tolerant corals capable of persisting in BARC despite repeated thermal anomalies. While early life stages exhibited short-term thermal tolerance, further research is needed to determine whether thermally exposed recruits experience long-term physiological or ecological trade-offs.
Laboratory evolution has been a powerful approach to address questions about evolvability. It has been debated whether the molecular chaperone, heat shock protein 90 (Hsp90), buffers or potentiates the effects of variation, and, consequently, constrains or accelerates evolution. In this study, we experimentally evolved yeast strains carrying mutant alleles of Hsp90-encoding genes under mild clotrimazole selection. We found that knockout of HSC82, which encodes a constitutively expressed Hsp90 chaperone, led to slower evolution of clotrimazole resistance in the short term. However, all strains generally evolved resistance within seven transfers, regardless of Hsp90 status. Through whole-genome sequencing, we identified genetic changes associated with clotrimazole resistance, including prevalent mitochondrial genome loss, as well as chromosomal duplications and point mutations. HSC82 knockout populations specifically showed convergent chromosomal duplications of chrVIII and chrXV. Taken together, our results demonstrate that disruption of Hsp90 in yeast may not alter the overall outcome of evolution but may shape its evolutionary trajectories at both the phenotypic and genotypic levels.
The application of the lampricide TFM (3-trifluoromethyl-4-nitrophenol) to streams infested with larval sea lamprey constitutes the backbone of the Sea Lamprey Control Program in the Laurentian Great Lakes, but native species have greatly varying sensitivities to TFM. Earlier work by D'Souza and colleagues revealed that the whole-animal oxygen consumption of larval sea lamprey responded in a dose-dependent manner to increasing TFM concentrations. We set out to determine 1) if TFM exposure leads to stepwise increases in whole-animal oxygen consumption in non-target fishes, and 2) if exposure to lethal TFM concentrations leads to increases in oxygen consumption comparable to the animals’ Maximum Metabolic Rate (MMR). Using intermittent-flow respirometry, we tested three non-target fish species with known varying TFM sensitivity: young-of-the-year lake sturgeon (sensitive), juvenile rainbow trout (intermediate), and juvenile smallmouth bass (resistant). We confirmed that all three species exhibit increases in oxygen consumption during exposure to increasing concentrations of TFM, but found that the relationship between MMR and oxygen consumption prior to death during lethal TFM exposure is complex and species-dependent. While this complex relationship broadens the need for species-specific testing, it opens up interesting possibilities both for (1) in-situ testing, e.g., through the deployment of river-side field respirometry systems to monitor real-time responses of both target and non-target species to TFM treatments, and (2) ex-situ testing, e.g., through the establishment of less-lethal assays to determine TFM sensitivity under various species × temperature × water chemistry combinations.
Monitoring heart rate (fH) accurately is fundamental for fish eco-physiological studies. However, these measurements rely heavily on expensive experimental tools. Here, we aimed to validate BITalino, an inexpensive, open-hardware biosignal acquisition system for measuring fH that could help to democratize research in fish physiology. BITalino is a modular electrophysiological system with a dedicated electrocardiogram (ECG) module that records ECG signals through electrodes connected to the module via lead wires and attached directly to the subject. We compared BITalino with a widely used research-grade physiological recording system (BIOPAC) by measuring fH in fish using both devices simultaneously. Heart-rate measurements did not differ significantly between devices, and there was no significant Device×Time interaction, indicating that both systems tracked temporal variation similarly. The intra-class correlation coefficient (ICC) showed that 85.9% of the variance was due to biological differences between fish, with less than 5% from device-related variance. These results confirm that BITalino can be effectively used for fH monitoring in fish physiology studies. Beyond its low cost, its portability, modular design, open-hardware architecture and compatibility with third-party analysis software make it easily adaptable for different experimental applications, and may facilitate its use in resource-limited research settings.
ABSTRACT Ecological syntheses (meta-analyses) usually ask ‘what is the average effect?’ But many questions also depend on whether outcomes become more or less variable and whether effects are predictable across contexts. We show how one dataset can support a workflow that synthesises both mean effects and within-group variability while also separating heterogeneity among study-level effects from residual heterogeneity among effect sizes within studies. Using an organic versus conventional crop-yield dataset, we analyse mean effects with the log response ratio (lnRR; Model 1) and within-group variability with the log variability ratio (lnVR) and log coefficient of variation ratio (lnCVR; Model 2), all calculated from the same summary statistics (means, s.d.s. and sample sizes). We then use multilevel location–scale meta-regression to test whether fertiliser type shifts expected lnRR and lnVR/lnCVR effects (Models 3 and 4) and whether residual and study-level heterogeneity differ between contexts. These heterogeneity components respectively inform consistency among represented comparisons and transferability to a new study. Analysing mean effects, within-group variability and context-dependent heterogeneity together can provide a more informative description of ecological responses than focusing on average effects alone.
