Biology subjects

Andreadis, C. R.

Publications and source records attributed to Andreadis, C. R..

4 recordsLinked to original sources

bioRxiv2026

Gut microbiota promote early-life digestive function in songbirds

The vertebrate digestive tract harbors complex microbial communities whose influences on phenotypes and fitness in non-model organisms remain poorly understood. Here, we show that colonization with gut microbiota is critical for digestive development and function in a non-model songbird, the House sparrow (Passer domesticus). We raised nestlings under sterile (axenic) conditions and compared them to nestlings reconstituted (conventionalized) with microbiota from adult sparrows. Conventionalization drove significant increases in villus length, crypt depth, goblet cell density, and mucosal thickness in the small intestine. Conventionalized nestlings also exhibited increased growth of several digestive organs and elevated circulating bile acid levels, including bacterial metabolites known to promote growth and lipid metabolism in vertebrates. These results reveal functions of songbird microbiota and establish axenic methods for non-model oviparous vertebrates.

microbiology↗

bioRxiv2026

Real-time heart rate in the wild: remote collection of cardiac data in baboons using a low-power Bluetooth and LoRaWAN system

O_LICardiac rate and rhythm reveal how animals adapt physiologically to day-to-day challenges, with consequences for health and fitness. However, these data remain difficult to collect in wild animals, despite their relevance for individual health and fitness. C_LIO_LIHere, we present a system for collecting and transmitting long-term, fine-scaled physiological data in wild animals. We implanted Bluetooth-enabled cardiac and physiological monitor devices in three wild adult female baboons in the Amboseli ecosystem in Kenya and paired these devices with collars that enabled remote data downloads over long-range wide area network (LoRaWAN). C_LIO_LIThe system performed well over >10 months, providing the first long-term cardiac data in wild primates. The baboons showed strong circadian patterns in heart rate, heart rate variability, and activity. We also present data on one female who left her social group for unknown reasons; while alone she exhibited higher heart rate variability, lower activity, and evidence of disrupted sleep. C_LIO_LIIn sum, physiologgers paired with low-energy methods of remote data retrieval are powerful tools for investigating physiology in wild animals on timescales that extend over many months, with minimal disruption to their behavior. C_LI

zoology↗

bioRxiv2026

Using insertable cardiac monitors to test determinants of heart rate and activity in captive baboons

BackgroundInsertable cardiac monitors (ICMs) provide fine-grained, continuous data on cardiac activity. These data have great potential to reveal individual physiology, energetics, and stress responses, with implications for animal health, cognition, welfare, and conservation. However, these devices must be tested for safety, accuracy, and biological validity before being deployed in new species. Here we do so for the Reveal LINQTM ICM (Medtronic, Minneapolis, MN USA) over an 8-month period in 10 adult female baboons (Papio anubis and P. cynocephalus) at the Kenya Institute of Primate Research in Kenya. We also report data on heart rate, physical activity, and body temperature in unrestrained, conscious, captive baboons during their normal activities. Finally, we test how heart rate and activity levels are predicted by baboon species, body mass, time of day, ambient temperature, social dominance rank, and ovarian cycle phase. ResultsThe baboons had no adverse reactions to the Reveal LINQTM ICM. Their mean daytime heart rates (HRs) ranged from 89.6 to 128.0 beats per minute (bpm), and their resting HRs ranged from 74.4 to 98.2 bpm. The fastest observed R-wave interval validated by electrocardiogram (ECG) was 230 milliseconds (ms) (260 bpm), and the slowest was 1270 ms (47.4 bpm). In terms of predictors of HR and activity, HR was highly individualized, while activity level was not: baboon identity explained 41% of the variation in HR, but identity only 2% of variation in activity levels. HR was positively correlated with physical activity and HR was highest during daylight hours when the baboons were more active. Dominant baboons had higher HRs controlling for activity and were more active than low ranking individuals. In terms of ovarian cycle phase, HR was higher when individuals were in the periovulatory and luteal phases of the ovarian cycle compared to the follicular phase. ConclusionsOur findings support the future use of ICMs to investigate physiological responses in baboons. These devices safety and validity represent the plausibility of understanding inter-individual and inter-species variation in heart rate and activity in response to variation in the external environment and in individual internal state.

zoology↗

bioRxiv2022

Adaptive remodeling of the gut microbiome over long-distance migration

The gut microbiome can be thought of as a forgotten organ, owing to its profound effects on host phenotypes. Long-distance migratory birds are capable of adaptively modulating their physiology, raising the hypothesis that the microbiome of migratory birds may undergo a parallel remodeling process that helps to meet the energetic demands of long-distance migration. To test this hypothesis, we investigated changes in gut microbiome composition and function over the fall migration of a Neotropical-Nearctic migratory Blackpoll Warbler (Setophaga striata), which exhibits one of the longest known autumnal migratory routes of any songbird and rapidly undergoes extensive physiological remodeling during migration. Overall, our results showed that the Blackpoll warbler microbiome differed significantly across phases of fall migration. This pattern was driven by a dramatic increase in the relative abundance of Proteobacteria, and more specifically a single ASV belonging to the family Enterobacteriaceae. Further, blackpolls exhibited a progressive reduction in microbiome phylogenetic diversity and within-group variances over migration, indicating convergence of microbiome composition among individuals during long-distance migration. Metagenomic analysis revealed that the gut microbiome of staging blackpolls was enriched in bacterial pathways involved in vitamin, amino acid, and fatty acid biosynthesis, as well as carbohydrate metabolism, and that these pathways were in turn positively associated with host body mass and subcutaneous fat deposits. Together, these results provide evidence that the gut microbiome of migratory birds may undergo adaptive remodeling to meet the physiological and energetic demands of long-distance migration.

ecology↗