Daniel Ari Shaykevich

All Publications

• Chronic recording of brain activity in awake toads. bioRxiv : the preprint server for biology Shaykevich, D. A., Woods, G. A., O'Connell, L. A., Hong, G. 2024

  Abstract

  Background: Amphibians represent an important evolutionary transition from aquatic to terrestrial environments and they display a large variety of complex behaviors despite a relatively simple brain. However, their brain activity is not as well characterized as that of many other vertebrates, partially due to physiological traits that have made electrophysiology recordings difficult to perform in awake and moving animals.New method: We implanted flexible mesh electronics in the cane toad (Rhinella marina) and performed extracellular recordings in the telencephalon of anesthetized toads and partially restrained, awake toads over multiple days.Results: We recorded brain activity over five consecutive days in awake toads and over a 15 week period in a toad that was anesthetized during recordings. We were able to perform spike sorting and identified single- and multi-unit activity in all toads.Comparison with existing methods: To our knowledge, this is the first report of a modern method to perform electrophysiology in non-paralyzed toads over multiple days, though there are historical references to short term recordings in the past.Conclusions: Implementing flexible mesh electronics in amphibian species will allow for advanced studies of the neural basis of amphibian behaviors.

  View details for DOI 10.1101/2024.10.16.618567

  View details for PubMedID 39463987

• Neural and sensory basis of homing behavior in the invasive cane toad, Rhinella marina. bioRxiv : the preprint server for biology Shaykevich, D. A., Pareja-Mejía, D., Golde, C., Pašukonis, A., O'Connell, L. A. 2024

  Abstract

  The behavioral, sensory, and neural bases of vertebrate navigation are primarily described in mammals and birds. However, we know much less about navigational abilities and mechanisms of vertebrates that move on smaller scales, such as amphibians. To address this knowledge gap, we conducted an extensive field study on navigation in the cane toad, Rhinella marina. First, we performed a translocation experiment to describe how invasive toads in Hawai'i navigate home following displacements of up to one kilometer. Next, we tested the effect of olfactory and magnetosensory manipulations on homing, as these senses are most commonly associated with amphibian navigation. We found that neither ablation alone prevents homing, suggesting that toad navigation is multimodal. Finally, we tested the hypothesis that the medial pallium, the amphibian homolog to the hippocampus, is involved in homing. By comparing neural activity across homing and non-homing toads, we found evidence supporting the involvement of the medial pallium, lateral pallium, and septum in navigation, suggesting a conservation of neural structures supporting navigation across vertebrates. Our study lays the foundation to understand the behavioral, sensory, and neural bases of navigation in amphibians and to further characterize the evolution of behavior and neural structures in vertebrates.

  View details for DOI 10.1101/2024.06.25.600658

  View details for PubMedID 38979178

  View details for PubMedCentralID PMC11230440

• Tissue-specific in vivo transformation of plasmid DNA in Neotropical tadpoles using electroporation. PloS one Delia, J., Gaines-Richardson, M., Ludington, S. C., Akbari, N., Vasek, C., Shaykevich, D., O'Connell, L. A. 2023; 18 (8): e0289361

  Abstract

  Electroporation is an increasingly common technique used for exogenous gene expression in live animals, but protocols are largely limited to traditional laboratory organisms. The goal of this protocol is to test in vivo electroporation techniques in a diverse array of tadpole species. We explore electroporation efficiency in tissue-specific cells of five species from across three families of tropical frogs: poison frogs (Dendrobatidae), cryptic forest/poison frogs (Aromobatidae), and glassfrogs (Centrolenidae). These species are well known for their diverse social behaviors and intriguing physiologies that coordinate chemical defenses, aposematism, and/or tissue transparency. Specifically, we examine the effects of electrical pulse and injection parameters on species- and tissue-specific transfection of plasmid DNA in tadpoles. After electroporation of a plasmid encoding green fluorescent protein (GFP), we found strong GFP fluorescence within brain and muscle cells that increased with the amount of DNA injected and electrical pulse number. We discuss species-related challenges, troubleshooting, and outline ideas for improvement. Extending in vivo electroporation to non-model amphibian species could provide new opportunities for exploring topics in genetics, behavior, and organismal biology.

  View details for DOI 10.1371/journal.pone.0289361

  View details for PubMedID 37590232

• Home security cameras as a tool for behavior observations and science equity. bioRxiv : the preprint server for biology Goolsby, B. C., Fischer, M., Pareja-Mejia, D., Lewis, A. R., Raboisson, G., Oa Connell, L. A. 2023

  Abstract

  Reliably capturing transient animal behavior in the field and laboratory remains a logistical and financial challenge, especially for small ectotherms. Here, we present a camera system that is affordable, accessible, and suitable to monitor small, cold-blooded animals historically overlooked by commercial camera traps, such as small amphibians. The system is weather-resistant, can operate offline or online, and allows collection of time-sensitive behavioral data in laboratory and field conditions with continuous data storage for up to four weeks. The lightweight camera can also utilize phone notifications over Wi-Fi so that observers can be alerted when animals enter a space of interest, enabling sample collection at proper time periods. We present our findings, both technological and scientific, in an effort to elevate tools that enable researchers to maximize use of their research budgets. We discuss the relative affordability of our system for researchers in South America, which is home to the largest population of ectotherm diversity.

  View details for DOI 10.1101/2023.04.17.537238

  View details for PubMedID 37131676

• Contrasting parental roles shape sex differences in poison frog space use but not navigational performance. eLife Pasukonis, A., Serrano-Rojas, S. J., Fischer, M., Loretto, M., Shaykevich, D. A., Rojas, B., Ringler, M., Roland, A. B., Marcillo-Lara, A., Ringler, E., Rodriguez, C., Coloma, L. A., O'Connell, L. A. 2022; 11

  Abstract

  Sex differences in vertebrate spatial abilities are typically interpreted under the adaptive specialization hypothesis, which posits that male reproductive success is linked to larger home ranges and better navigational skills. The androgen spillover hypothesis counters that enhanced male spatial performance may be a byproduct of higher androgen levels. Animal groups that include species where females are expected to outperform males based on life-history traits are key for disentangling these hypotheses. We investigated the association between sex differences in reproductive strategies, spatial behavior, and androgen levels in three species of poison frogs. We tracked individuals in natural environments to show that contrasting parental sex roles shape sex differences in space use, where the sex performing parental duties shows wider-ranging movements. We then translocated frogs from their home areas to test their navigational performance and found that the caring sex outperformed the non-caring sex only in one out of three species. In addition, males across species displayed more explorative behavior than females and androgen levels correlated with explorative behavior and homing accuracy. Overall, we reveal that poison frog reproductive strategies shape movement patterns but not necessarily navigational performance. Together this work suggests that prevailing adaptive hypotheses provide an incomplete explanation of sex differences in spatial abilities.

  View details for DOI 10.7554/eLife.80483

  View details for PubMedID 36377473

• Long distance homing in the cane toad (Rhinella marina) in its native range. The Journal of experimental biology Shaykevich, D. A., Pasukonis, A., O'Connell, L. A. 1800

  Abstract

  Many animals exhibit complex navigation over different scales and environments. Navigation studies in amphibians have largely focused on species with life histories that require accurate spatial movements, such as territorial poison frogs and migratory pond-breeding amphibians that show fidelity to mating sites. However, other amphibian species have remained relatively understudied, leaving open the possibility that well-developed navigational abilities are widespread. Here, we measured short-term space use in non-territorial, non-migratory cane toads (Rhinella marina) in their native range in French Guiana. After establishing site fidelity, we tested their ability to return home following translocations of 500 and 1000 meters. Toads were able to travel in straight trajectories back to home areas, suggesting navigational abilities similar to those observed in amphibians with more complex spatial behavior. These observations break with the current paradigm of amphibian navigation and suggest that navigational abilities may be widely shared among amphibians.

  View details for DOI 10.1242/jeb.243048

  View details for PubMedID 34940881