Biology subjects

Leopold, D.

Publications and source records attributed to Leopold, D..

5 recordsLinked to original sources

bioRxiv2026

Airborne DNA reveals synchronized responses of tropical forest assemblages to precipitation

Tropical forests contain much of Earth's biodiversity, yet community-wide responses to seasonal climate transitions remain poorly resolved. We used weekly airborne environmental DNA sampling, supplemented by spatially intensive dry- and wet-season campaigns, to characterize fungi, plants, arthropods, and vertebrates across the dry-to-wet-season transition in a lowland tropical forest. All four assemblages shifted abruptly and nearly synchronously following rainfall late in the dry season, before the meteorological wet season began. These compositional transitions were largely independent of taxonomic richness and airborne DNA concentrations, indicating coordinated changes in detection patterns rather than simple seasonal gains in richness. Across all samples, we recovered more than 5,400 operational taxonomic units, including 2,148 fungi, 857 plants, 2,157 arthropods, and 239 vertebrates. We also recovered 949 full-length insect DNA barcodes, demonstrating compatibility with standard barcoding approaches and expanding opportunities for species discovery. Because the onset of the meteorological wet season showed no long-term trend at Barro Colorado Island, predicting future phenological and compositional shifts will require greater attention to dry-season rainfall variability and the cues that organisms track during this transition. Airborne environmental DNA offers a scalable, noninvasive framework for monitoring biodiversity and phenology across taxonomic groups.

ecology↗

bioRxiv2026

Targeted hybridization capture enables comprehensive detection of freshwater bioassessment invertebrates from environmental DNA

Freshwater bioassessment relies on assessing aquatic assemblages to infer ecological conditions, yet conventional surveys require extensive field sampling, specimen processing, and specialized taxonomic expertise. Existing environmental DNA (eDNA) methods have not yet provided a practical alternative to conventional macroinvertebrate assays in part because current approaches cannot feasibly recover broad taxonomic diversity at sufficient taxonomic resolution. Here, we evaluated targeted hybridization capture of mitochondrial cytochrome oxidase I (COI) target sequences as a unified molecular approach for cross-phylum freshwater bioassessment. Environmental DNA was collected at 18 sites along 63 km of Boulder Creek spanning nearly 1,500 m of elevation from forested headwaters to agricultural plains. COI targets were enriched using custom RNA bait panels designed to target regional freshwater arthropods, annelids, and molluscs. Hybridization capture increased recovery of COI sequences [~]1,760-fold relative to unenriched shotgun libraries, generating Folmer-region COI contigs that averaged [~]400 bp. Across the watershed, we recovered sequences for approximately 450 macroinvertebrate genera across 8 phyla. Detected macroinvertebrate richness averaged 56 genera per site and increased down Boulder Canyon before declining downstream of the city. Macroinvertebrate assemblage composition from hybridization capture paralleled patterns observed with past conventional bioassessment. These results demonstrate that targeted hybridization capture enables robust, cross-phylum detection of species used for freshwater bioassessment from environmental DNA.

ecology↗

bioRxiv2025

Surveying Tropical Faunal Diversity via Airborne DNA Analyses

Here, we assess the potential of airborne eDNA (airDNA) metabarcoding to characterize arthropod and vertebrate assemblages in a tropical forest. We deployed 28 high-flow air samplers across a 1.5 km2 area on Barro Colorado Island, Panama, over two consecutive 24- hour periods and sequenced captured DNA using general eukaryotic and vertebrate-specific metabarcoding primers. AirDNA sampling detected 1293 arthropod operational taxonomic units (OTUs) alongside 157 vertebrate OTUs representing birds, mammals, reptiles, amphibians, and fish. Arthropod richness was comparable to that quantified locally with light and Malaise trap surveys, while vertebrate richness exceeded that typically observed with conventional techniques. The level of field and lab effort employed in this study captured approximately 84% of the asymptotic richness for arthropods and 76% for vertebrates, implying that relatively little additional richness would have been quantified with additional effort within the same domain of sampling. Observed and asymptotic richness increased with the number of sites, the number of days a site was sampled, and the number of PCR replicates run per sample, highlighting the need to standardize effort among future applications of airDNA to compare richness across systems. These results demonstrate that airDNA metabarcoding can efficiently and non- invasively profile tropical terrestrial faunal biodiversity.

ecology↗

bioRxiv2024

Propagating cortical waves coordinate sensory encoding and memory retrieval in the human brain

Complex behavior entails a balance between taking in sensory information from the environment and utilizing previously learned internal information. Experiments in behaving mice have demonstrated that the brain continually alternates between outward and inward modes of cognition, switching its mode of operation every few seconds. Further, each state transition is marked by a stereotyped cascade of neuronal spiking that pervades most forebrain structures. Here we analyzed large fMRI datasets to demonstrate that a similar switching mechanism governs the operation of the human brain. We found that human brain activity was punctuated every several seconds by coherent, propagating waves emerging in the exteroceptive sensorimotor regions and terminating in the interoceptive default mode network. As in the mouse, the issuance of such events coincided with fluctuations in pupil size, indicating a tight relationship with arousal fluctuations, and this phenomenon occurred across behavioral states. Strikingly, concurrent measurement of human performance in a visual memory task indicated that each cycle of propagating fMRI waves sequentially promoted the encoding of semantic information and self-directed retrieval of memories. Together, these findings indicate that human cognitive performance is governed by autonomous switching between exteroceptive and interoceptive states. This apparently conserved feature of mammalian brain physiology bears directly on the integration of sensory and mnemonic information during everyday behavior.

neuroscience↗

bioRxiv2022

Self-generated brain-wide spiking cascades govern replay dynamics in the hippocampus

During states of behavioral quiescence, neurons in the hippocampus replay sequences of spiking activity experienced in earlier behavioral episodes. While such replay sequences are hypothesized to serve learning and memory by facilitating synaptic consolidation, their generative mechanisms remain poorly understood. Increasing evidence suggests that they might be generated internally, or at least strongly constrained by internal circuit dynamics. Recent work demonstrated that, across the forebrain, approximately 70% of neurons participate in a pattern of sequential spiking cascades during rest. Like hippocampal replay sequences, these brain-wide spiking cascades occur together with high-frequency hippocampal ripples and therefore may share a common generative mechanism. Here we systematically investigated the relationship between replay activity and sequential spiking cascades by analyzing a database of intracortical electrocortical recordings in mice. For neuronal subpopulations in the hippocampus and visual cortex, we assessed spiking sequences elicited during video viewing as well as potential replay events during subsequent periods of rest. We found that replay events were unique to hippocampal time-sensitive neurons and occurred together with spiking cascades throughout the forebrain. Furthermore, forward and time-reversed replay sequences were associated with different types of spiking cascades. Overall, these findings indicate that hippocampal replay events are generated and structured according to resting state circuit dynamics manifest across a large portion of the brain.

neuroscience↗