Biology subjects

Gruber, D. F.

Publications and source records attributed to Gruber, D. F..

4 recordsLinked to original sources

bioRxiv2026

Orca vowels and consonants: convergent spectral structures across cetacean and human speech

The vocal communication system of orcas (Orcinus orca) has so far been analyzed primarily in terms of the fundamental frequency (F0) modulations, i.e. the frequency of their phonic lips vibration. The calls have been divided into clicks, pulsed calls, whistles and types thereof. By analyzing 61 hours of on-orca acoustic recordings and controlling for the effect of high-frequency components (HFC) and F0, we report structured formant patterns in orca vocalizations including diphthongal trajectories. Broadband spectrogram analysis reveals previously unreported formant patterns that appear independent of F0 and HFC and are hypothesized to result from air sac resonances. This study builds on the recent report of formant structure in vowel- and diphthong-like calls in another cetacean, sperm whales (Physeter macrocephalus). Using linguistic techniques, we further demonstrate that some calls are reminiscent of human consonant-vowel sequences, featuring bursts or abrupt decreases in amplitude. We also show that individual sparsely distributed clicks gradually transition into high frequency tonal calls, which aligns with analysis of sperm whale codas as vocalic pulses. The paper makes methodological contributions to the cetacean communication research by analyzing orca vocalizations with both narrowband and broadband spectrograms. The reported patterns are hypothesized to be actively controlled by whales and may carry communicative information. The spectral patterns shown in this study provide an added dimension to the orca communication system that merits further analysis and demonstrates convergent evolutions of similar phonological features in cetaceans (orca and sperm whale) and human communication systems.

animal behavior and cognition↗

bioRxiv2024

Velamins: the first green-light emitting class of wild-type Ca2+-regulated photoproteins isolated from the ctenophore Velamen parallelum

Ca2+-regulated photoproteins (CaPhs) consist of single-chain globular proteins to which coelenterazine, a widely distributed marine luminogenic substrate (the luciferin), binds along with molecular oxygen, producing a stable peroxide. Upon Ca2+ addition, CaPhs undergo conformational changes leading to the cyclization of the peroxide and the formation of a high-energy intermediate. Subsequently, its decomposition yields coelenteramide in an excited state and results in the emission of a flash of light. To date, all CaPhs reported produce blue light ({lambda}max 465-495 nm). Here, we report the cloning and functional characterization of a novel class of wild-type CaPhs capable of emitting green light: velamins, isolated from the bioluminescent ctenophore Velamen parallelum. Ten unique photoprotein-like sequences were recovered and grouped in three main clusters. Representative sequences were cloned, expressed, purified, and regenerated into the active His-tagged -, {beta}-, and {gamma}-velamins. Upon injection of a calcium-containing buffer into the velamin, a flash of green light ({lambda}max 500-508 nm) was observed across pH values ranging from 7 to 9. Whilst -velamin isoforms exhibited the highest light emission activity, {beta}- and {gamma}-velamins were found to be more thermostable at higher temperatures. Velamins are the only known wild-type Ca2+-regulated photoproteins that exhibit the longest wavelength in light emission, making them a promising model for studying spectral modulation. As a result, velamins hold potential for enhancing the sensitivity of signal detection in analytical systems, particularly when dealing with complex biological matrices.

biochemistry↗

bioRxiv2020

Molecular evolution of luciferase diversified bioluminescent signals in sea fireflies (Crustacea:Ostracoda:Cypridinidae)

Understanding the genetic causes of evolutionary diversification is challenging because differences across species are complex, often involving many genes. However, cases where single or few genetic loci affect a feature that varies dramatically across a radiation of species would provide tractable opportunities to understand the genetics of diversification. Here, we show the diversification of bioluminescent signals in cypridinid ostracods ("sea fireflies") to be strongly influenced by a single gene, cypridinid-luciferase. We find different evolutionary processes, including selection, drift, and constraint, each acted on c-luciferase at different times during evolutionary history and impacted different phenotypes, diversifying behavioral signals across species. In particular, some amino acid sites in c-luciferase evolved under episodic diversifying selection, and are associated significantly with phenotypic changes in both enzyme kinetics and color, which impact signals directly. We also find that multiple other amino acid positions in c-luciferase evolved neutrally or under purifying selection and may have impacted the variation of color of bioluminescent signals across genera. This work provides a rare glimpse into the genetic basis of diversification across many species, showing how multiple evolutionary processes may act at different times during a radiation of species to diversify phenotypes. These results indicate not only selection but also drift and constraint may be important evolutionary drivers of species diversification. Significance statementA hallmark of life is its astounding diversity. While we are beginning to understand the drivers of biodiversity, uncovering the genetic basis remains challenging. As such, how different molecular evolutionary processes act to diversify phenotypes is a major question in biology. Here we show a single gene to be important in a riotous diversity of fantastical behaviors - the bioluminescent signals of sea fireflies - allowing us to demonstrate multiple evolutionary forces including selection, drift, and constraint contributed to diversification. Our work highlights that not only selection but also neutral processes and constraint have each worked at different times to shape phenotypic diversity.

evolutionary biology↗

bioRxiv2018

Molecular phylogeny of Odontosyllis (Annelida, Syllidae): A recent and rapid radiation of marine bioluminescent worms.

Marine worms of the genus Odontosyllis (Syllidae, Annelida) are well known for their spectacular bioluminescent courtship rituals. During the reproductive period, the benthic marine worms leave the ocean floor and swim to the surface to spawn, using bioluminescent light for mate attraction. The behavioral aspects of the courtship ritual have been extensively investigated, but little is known about the origin and evolution of light production in Odontosyllis, which might in fact be a key factor shaping the natural history of the group, as bioluminescent courtship might promote speciation. To investigate the speciation patterns and evolutionary history of Odontosyllis and to trace the origin of bioluminescence within the group, we inferred phylogenies using both gene concatenation and multispecies coalescent species-tree approaches with a multilocus molecular dataset (18S rRNA, 16S rRNA and COI). We also used this dataset to estimate divergence times and diversification rates in a relaxed molecular clock Bayesian framework. Our results suggest that Odontosyllis has undergone a recent rapid radiation, possibly triggered by the origin of bioluminescent courtship, which might have increased speciation rates and lineage divergence through sexual selection. Additionally, our analyses reveal that the genus Odontosyllis as currently delineated is a paraphyletic group that needs to be reorganized to reflect evolutionary relationships.

evolutionary biology↗