Biology subjects

Grether, G.

Publications and source records attributed to Grether, G..

3 recordsLinked to original sources

bioRxiv2026

Predation by migratory birds shapes seasonally fluctuating selection on a sexually selected signal

Sexually selected traits often impose fitness costs on their bearers. Yet, the relative costs and benefits of conspicuous traits can vary through space and time, driving variation in selection acting on those traits. For insects, an important but overlooked source of such variation is seasonal shifts in the local abundance of migratory insectivorous birds. Smoky rubyspot damselflies (Hetaerina titia) exhibit a marked seasonal polyphenism in wing pigmentation throughout much of North America, with individuals emerging in the summer exhibiting conspicuous dark wings. Here, we test the hypothesis that this variation is an adaptive response to seasonal and geographical variation in predation risk. First, we find evidence for strong constraints acting on wing phenotypes outside of the summer season, consistent with a seasonal shift in the relative costs and benefits of pigmentation. Second, using a continentally distributed predation experiment, we find that predation risk covaries with spatiotemporal variation in wing pigmentation and is linked to shifts in the local abundance of migratory birds. Overall, our analyses establish an eco-evolutionary link between tropical and temperate regions, underscoring the importance of considering both the evolutionary and ecological consequences of spatiotemporal variation in biotic interactions as species assemblages shift in response to global change.

evolutionary biology↗

bioRxiv2025

VDisk: Microfluidic Cartridge for Multimodal High-Yield, High-Purity Isolation of Extracellular Vesicles from up to 1 mL of Plasma

Blood-derived extracellular vesicles (EVs) hold strong diagnostic potential, yet conventional isolation methods such as ultracentrifugation and size-exclusion chromatography (SEC) involve manual handling steps and show substantial run-to-run variability, hindering clinical translation. This study presents the Vesicle Disk (VDisk), a centrifugal microfluidics-based EV purification platform that combines cation-exchange chromatography, sequential filtration, and multimodal chromatography for automated, label-free EV isolation from up to 1 mL of plasma. VDisk configurations differing in filter membrane and plasma volume (0.1-1.0 mL) are benchmarked against SEC for yield, purity, reproducibility and robustness. VDisk matches SEC in EV yield and exceeds it in EV/contaminant ratios at reduced input volumes, while achieving greater reproducibility (intra-donor CV < 5% for CD9 and CD81, versus up to 16% for SEC) and maintaining consistent yield and contaminant removal under both fasting and postprandial sampling conditions. The platform is application-tunable: processing up to 1 mL of plasma maximizes EV yield and concentration, whereas processing 0.5 mL achieves approximately 2-3-fold higher EV/total protein ratios than SEC. These findings establish the VDisk as an automated, robust and adaptable alternative to existing EV isolation methods for both research and clinical translation.

bioengineering↗

bioRxiv2024

Spatiotemporal dynamics of non-ecological speciation in rubyspot damselflies (Hetaerina spp.)

Non-ecological speciation is a common mode of speciation which occurs when allopatric lineages diverge in the absence of pronounced ecological differences. Yet, relative to other speciation mechanisms, non-ecological speciation remains understudied. Numerous damselfly clades are characterized as non-adaptive radiations (the result of several rounds of non-ecological speciation), but there are few damselfly lineages for which we have a detailed understanding of the spatiotemporal dynamics of divergence. Recent phylogeographic analyses demonstrate that American rubyspot damselflies (Hetaerina americana sensu lato) actually comprise at least two cryptic lineages that coexist sympatrically across most of Mexico. To broaden our understanding of the dynamics of diversification to other rubyspot lineages, we investigated the phylogeographic history of smoky rubyspot damselflies (Hetaerina titia) using genomic data collected across Central and North America. Unexpectedly, we found evidence of reproductive isolation between the highly genetically differentiated Pacific and Atlantic lineages of H. titia in a narrow secondary contact zone on the Isthmus of Tehuantepec, Mexico. We then fit models of historical demography to both H. americana sensu lato and H. titia to place these comparisons in a temporal context. Our findings indicate that Pacific and Atlantic lineages of H. titia split more recently than the broadly sympatric lineages within H. americana sensu lato, supporting key assumptions of the non-ecological speciation model and demonstrating that these two pairs of sister lineages are at different stages of the speciation cycle.

evolutionary biology↗