Biology subjects

Marek, P. E.

Publications and source records attributed to Marek, P. E..

3 recordsLinked to original sources

bioRxiv2026

Integrative taxonomy of the North American pink flat-backed millipedes (Polydesmidae: Pseudopolydesmus Attems, 1898)

Millipedes of the genus Pseudopolydesmus Attems, 1898 are common millipedes in North America. They are the largest, in terms of body size, and most geographically wide-ranging of the family Polydesmidae, and are ubiquitous in eastern and central North American forests. Eight species have been named based on the morphology of the genitalia, but these have not been investigated genetically. Here, we take an integrated taxonomic approach, using five genes to infer a molecular phylogeny of Pseudopolydesmus species, and analyze a dataset of 15 morphological characters in an effort to delimit species in the genus. 1,148 Pseudopolydesmus specimens were newly collected for this study, and all known species were sampled. These specimens were used for analysis, and were combined with museum specimens and literature records into a database of 3,462 unique specimen records. This database was used to produce distribution maps for each species in the genus. The maximum likelihood phylogeny found support for the eight species in the genus, supporting previous morphological species hypotheses. However, previous morphology-based hypotheses regarding evolutionary relationships between the species were not supported by the analysis. The morphological analysis, performed with a modified PCA, did not delimit species clusters as well as the genitalic and genetic differences did, due to comparatively uniform somatic morphology in the genus. However, our results show that genitalic morphology, combined with genetic analysis, provide congruent species delimitation hypotheses for Pseudopolydesmus, and these lines of evidence may prove useful in delimiting species and generic boundaries in other Polydesmidae worldwide.

evolutionary biology↗

bioRxiv2021

3D-imaging inspired improvements to hearing model in parasitoid fly Ormia ochracea

This manuscript was compiled on October 5, 2021 Although most binaural organisms localize sound sources using neurological structures to amplify the sounds they hear, some animals use mechanically coupled hearing organs instead. One of these animals, the parasitoid fly Ormia ochracea, has astoundingly accurate sound localization abilities and can locate objects in the azimuthal plane with a precision of 2{degrees}, equal to that of humans. This is accomplished despite an intertympanal distance of only 0.5 mm, which is less than 1/100th of the wavelength of the sound emitted by the crickets that it parasitizes. In 1995, Miles et al. developed a model of hearing mechanics in O. ochracea, which works well for incoming sound angles of less than {+/-}30{degrees}, but suffers from reduced accuracy (up to 60% error) at higher angles. Even with this limitation, it has served as the basis for multiple bio-inspired microphone designs for decades. Here, we present critical improvements to the classic O. ochracea hearing model based on information from 3D reconstructions of O. ochraceas tympana. The 3D images reveal that the tympanal organ has curved lateral faces in addition to the flat front-facing prosternal membranes represented in the Miles model. To mimic these faces, we incorporated spatially-varying spring and damper coefficients that respond asymmetrically to incident sound waves, making a new quasi-two-dimensional (q2D) model. The q2D model has high accuracy (average errors of less than 10%) for the entire range of incoming sound angles. This improved biomechanical hearing model can inform the development of new technologies and may help to play a key role in developing improved hearing aids. Significance StatementThe ability to identify the location of sound sources is critical to organismal survival and for technologies that minimize unwanted background noise, such as directional microphones for hearing aids. Because of its exceptional auditory system, the parasitoid fly Ormia ochracea has served as an important model for binaural hearing and a source of bioinspiration for building tiny directional microphones with outsized sound localization abilities. Here, we performed 3D imaging of the flys tympanal organs and used the morphological information to improve the current model for hearing in O. ochracea. This model greatly expands the range of biological accuracy from {+/-}30{degrees} to all incoming sound angles, providing a new avenue for studies of binaural hearing and further inspiration for fly-inspired technologies.

biophysics↗

bioRxiv2019

Diversity and function of fungi associated with the fungivorous millipede, Brachycybe lecontii

Fungivorous millipedes (subterclass Colobognatha) likely represent some of the earliest known mycophagous terrestrial arthropods, yet their fungal partners remain elusive. Here we describe relationships between fungi and the fungivorous millipede, Brachycybe lecontii. Their fungal community is surprisingly diverse with 176 genera, 39 orders, and four phyla and includes several undescribed species. Of particular interest are twelve genera conserved across wood substrates and millipede clades that comprise the core fungal community of B. lecontii. Wood decay fungi, long speculated to serve as the primary food source for Brachycybe species, were absent from this core assemblage and proved lethal to millipedes in pathogenicity assays while entomopathogenic Hypocreales were more common in the core but had little effect on millipede health. This study represents the first survey of fungal communities associated with any colobognath millipede, and these results offer a glimpse into the complexity of millipede fungal communities.

microbiology↗