Biology subjects

Gray, D. A.

Publications and source records attributed to Gray, D. A..

5 recordsLinked to original sources

bioRxiv2026

A shared circuit architecture for multiscale signal recognition in crickets

Communication signals often contain behaviorally relevant structure on multiple temporal scales. Short-timescale features are commonly thought to be recognized first and then integrated into longer-timescale representations. Whether a shared circuit can instead recognize multiple timescales remains unclear. Cricket calling songs provide a tractable test because millisecond-scale pulses are grouped into chirps lasting hundreds of milliseconds. We combined female phonotaxis with a mechanistic model of the identified pulse-recognition network to ask whether this circuitry can also generate chirp selectivity. In Gryllus bimaculatus, the model, originally parameterized from pulse-scale electrophysiology and behavior, recovered the main boundaries of chirp preference without fitting to chirp behavior. Coincidence detection generated the minimum chirp-duration requirement, whereas suppressive computations in the networks input neuron shaped the upper boundaries for chirp duty cycle and period. Across 14 species, varying these suppressive computations captured major differences in chirp tuning. These findings reveal a temporally interleaved serial circuit in which long-timescale selectivity begins upstream of completed short-timescale selectivity, offering an alternative to both conventional short-first hierarchies and parallel pathways.

neuroscience↗

bioRxiv2026

A feedback between dispersal and hybridization may facilitate the repeated emergence of flight in field crickets

Dispersal and hybridization can reinforce one another in a feedback loop when species that disperse farther are more likely to encounter and mate with close relatives, resulting in gene flow that can reintroduce dispersal-enhancing alleles in their descendants. This dynamic could help explain why complex dispersal-related traits, such as flight in insects, appear to evolve repeatedly within a clade, but this idea has rarely been tested with genomic data. North American Gryllus field crickets, in which flight capability appears to have been regained from flightless ancestors at least nine independent times, offer a powerful system to do so. Using a genome-wide dataset, we test three predictions about the origins of phylogenetic discordance in Gryllus and the role of dispersal-related traits. First, we find that both incomplete lineage sorting (ILS) and hybridization contribute to extensive gene tree conflict observed across the Gryllus phylogeny, but several conflicting patterns cannot be explained by ILS alone. Multiple lines of evidence reveal introgression at both deep and recent nodes, producing a mosaic evolutionary history with reticulation across many lineages. Second, hybridization is disproportionately concentrated among flight-capable lineages, supporting the idea that dispersal ability increases opportunities for interspecific gene flow. Third, introgression from flight-capable lineages could help explain repeated trait reversal across the phylogeny, suggesting that allele flow may have contributed to the re-emergence of flight in descendants of flightless ancestors. These results are consistent with a dispersal-hybridization feedback shaping both the reticulated phylogenetic history of Gryllus and the repeated emergence of flight. More broadly, models of character evolution built on bifurcating trees may overestimate the number of independent trait origins when reticulate processes are ignored.

evolutionary biology↗

bioRxiv2020

Muscle fiber type differences in nitrate and nitrite storage and nitric oxide signaling in rats

Recent studies have emphasized the importance of the nitric oxide synthase (NOS)-independent, nitrate (NO3-) [->] nitrite (NO2-) [->] nitric oxide (NO) pathway in skeletal muscle. In particular, it has been hypothesized that this pathway is especially active in type II, or fast-twitch, muscle fibers, necessitating greater NO3- and NO2- storage. We therefore measured NO3- and NO2- concentrations in the predominantly fast-twitch vastus lateralis and predominantly slow-twitch soleus muscles of rats. Contrary to the above hypothesis, we found that NO3- and NO2- concentrations were 3.4-fold and 1.8-fold higher, respectively, in the soleus. On the other hand, NO signaling (i.e., cyclic guanosine monophosphate (cGMP) level) was comparable in the two muscles. Although the physiological significance of these observations remains to be determined, we speculate that NO production via the NO3- [->] NO2- [->] NO pathway is normally higher in slow-twitch muscles, thus helping compensate for their inherently lower NOS activity.

physiology↗

bioRxiv2019

Molecular biogeography and host relations of a parasitoid fly

Successful geographic range expansion by parasites and parasitoids may also require host range expansion. Thus the evolutionary advantages of host specialization may trade off against the ability to exploit new host species encountered in new geographic regions. Here we use molecular techniques and confirmed host records to examine biogeography, population divergence, and host flexibility of the parasitoid fly, Ormia ochracea (Bigot). Gravid females of this fly find their cricket hosts acoustically by eavesdropping on male cricket calling songs; these songs vary greatly among the known host species of crickets. Using both nuclear and mitochondrial genetic markers, we (1) describe the geographical distribution and sub-division of genetic variation in O. ochracea from across the continental United States, the Mexican states of Sonora and Oaxaca, and populations introduced to Hawaii; (2) demonstrate that the distribution of genetic variation among fly populations is consistent with a single widespread species with regional host specialization, rather than locally differentiated cryptic species, (3) identify the more-probable source populations for the flies introduced to the Hawaiian islands; (4) examine genetic variation and sub-structure within Hawaii; and (5) discuss specialization and lability in host-finding behavior in light of the diversity of cricket songs serving as host cues in different geographically separate populations.

evolutionary biology↗

bioRxiv2019

A single dose of dietary nitrate increases maximal muscle speed and power in healthy older men and women

BackgroundAging results in reductions in maximal muscular strength, speed, and power, which often lead to functional limitations highly predictive of disability, institutionalization, and mortality in the elderly. This may be partially due to reduced nitric oxide (NO) bioavailability. We therefore hypothesized that dietary nitrate (NO3-), a source of NO via the NO3- [->] nitrite (NO2-) [->] NO enterosalivary pathway, could increase muscle contractile function in older subjects. MethodsTwelve healthy older (age 71{+/-}1 y) subjects were studied using a randomized, doubleblind, placebo-controlled, crossover design. After fasting overnight, subjects were tested 2 h after ingesting beetroot juice containing or devoid of 13.4{+/-}0.5 mmol NO3-. Plasma NO3- and NO2- and breath NO were measured periodically, and muscle function was determined using isokinetic dynamometry. ResultsNO3- ingestion increased (P<0.001) plasma NO3-, plasma NO2-, and breath NO by 1050%, 140%, and 110%, respectively. Maximal velocity of knee extension increased (P<0.01) by 1.1{+/-}0.3 rad/s, or by 10.9{+/-}3.5%. Maximal knee extensor power increased (P<0.05) by 0.14{+/-}0.06 W/kg, or by 4.4{+/-}2.3%. ConclusionsAcute dietary NO3- intake improves muscle contractility in older individuals. These findings have important implications for this population, in whom diminished muscle function can lead to functional limitations, dependence, and even premature death.

physiology↗